JP2003194338A - Method for controlling gas turbine engine fuel-air premixer with variable geometry exit and for controlling exit velocity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas turbine engine fuel-air premixer which controls fuel-air mixture exit velocities and also to provide a method for controlling fuel-air mixture exit velocities. <P>SOLUTION: The premixer, designed to mix fuel and air for the supply of a fuel-air mixture, has a mixing tube for fuel and air to flow into, a mixing tube axis, and a mixing tube outlet for the fuel-air mixture to flow out and, also, a mixing valve connected to the mixing tube outlet and an inner and outer valve members constituting an outlet flow region. In the outlet flow region, the mixture flows out in at least two substantially opposite directions, with the directions forming angles with the mixing tube axis formed by the outer valve member. For the predetermined outlet flow region to be selectively varied, at least one of the valve members is movable relative to the other. In gas turbine type gas generators or in gas turbine engine applications, the fuel-air ratio in the mixture can be controlled by using a combustion air valve and a fuel valve which are independently controllable. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to gas turbine gas generators and gas turbine engines which have the significant advantage of generally producing only low levels of pollutants (nitrogen oxides, carbon monoxide and unburned hydrocarbons). Other combustor systems for heat engines. In particular, the present invention relates to a single stage, fuel / air ratio controllable combustor for a gas turbine engine and gas generator using a fuel / air premixer assembly with a controllable variable outlet geometry of the premixer.

[0002]

Gas turbine equipment, such as engines and gas generators, emit little nitrogen oxides into the atmosphere, but reducing the emission of these nitrogen oxides will reduce the total amount of nitrogen oxides. This will contribute to the reduction, and in that respect many countries have enacted legislation that limits the emission of nitrogen oxides. The reaction between nitrogen and oxygen, which produces nitrogen oxides in the atmosphere, proceeds rapidly with increasing temperature, as in almost all chemical reactions. One way to limit the amount of NOx produced is to limit the reaction temperature.
The NOx produced in the gas turbine system is usually produced in the combustion process where the highest temperature exists during the cycle. Therefore, one way to limit the amount of NOx produced is to limit the reaction temperature.

A "single-stage" combustor having a single combustion zone for introducing fuel and air, and a pilot burner with several combustion zones connected in series with separate fuel and air introducing means. In both multi-stage "combustors, various attempts have been made to limit the combustion temperature and thereby NOx production. U.S. Pat.No. 4,994,149
U.S. Patent No. 4,297,842 and U.S. Patent No. 4,255,927.
U.S. Pat. No. 5,968,049 discloses a single stage gas turbine combustor that controls the flow of compressed air to the combustion and dilution zones of an annular combustor to reduce the concentration of NOx in turbine exhaust gas. In the combustor, fuel and air that are poorly mixed enter the combustor separately, and then mixing and combustion take place in the same chamber (see, for example, US Pat. No. 6,037,049). US Patent No.
5,069,029, U.S. Pat.No. 4,898,001, U.S. Pat.
No. 829,764 and U.S. Pat. No. 4,766,721 disclose a two-stage combustor (also see US Pat. However, fuel and air are delivered to each stage at least partially unmixed, with complete mixing occurring within each combustion zone.

Attempts have also been made to utilize separate premixer chambers to provide a premixed fuel / air stream to the combustor, eg, the total fuel stream introduced into a multi-stage can combustor. Of the combustor system is disclosed in which a part of the above is premixed in another mixing chamber before being introduced into the staged combustion chamber (see, for example, Patent Document 3). Also, a number of separate fuel nozzles are used to inject fuel into the annular premixer chamber (see, eg, US Pat.
reference). However, the above structure using a plurality of fuel nozzles and a fuel branching device has a problem in that it is difficult to control because of its complexity and the initial cost is high.

[0005]

[Patent Document 1] JP-A-55-45739

[Patent Document 2] West German Utility Model No. 9215856

[Patent Document 3] JP-A-57-41524

[Patent Document 4] US Pat. No. 5,016,443

[0006]

A single stage combustor system using an external premixer is disclosed, for example, in US Pat. No. 5,377,
No. 483, No. 5,477,671, No. 5,481,866, No. 5,
It is known by the inventor's earlier proposals, as disclosed in 572,862, 5,613,357 and 5,638,674. These systems use a Venturi mixing tube to premix all fuels with almost all combustion air and introduce the resulting mixture into the combustion zone of the combustor to ensure a precise fuel / air ratio. To control. Using the inventions disclosed in the above referenced patents, gas and particulate emissions have been significantly reduced by gas turbine engines and modules under a wide range of operating conditions.

However, there is a premixer system for a single stage combustor that can reduce "flashback" from the combustor to the premixer (which occurs when the velocity of the flame is greater than the velocity of the fuel / air mixture in the premixer). Is desired. Flashback adversely affects the mechanical performance of the premixer system and associated structures. In particular, it is desirable to design a premixer system that can reduce the flow separation that occurs in the premixer due to the geometry of the premixer components. Flash separation can occur in the premixer due to flow separation.

It is further desirable to provide a premixer system that can reduce the pulsation that occurs in the flow of the fuel / air mixture delivered from the premixer to the combustion chamber. Pulsation occurs due to instability of the mixture flow within the combustor due to fluctuations in the mixture flow rate exiting the premixer and too fast. Pulsation can adversely affect the combustor liner and engine construction.

Further, the fuel / air mixture is delivered to the combustion chamber so as to reduce the impingement of the flow of the fuel / air mixture on the combustor liner while maintaining a relatively simple geometry of the overall structure. It is desired to provide a premixer system that can. When the flow of the fuel / air mixture impinges on the liner wall, the amount of carbon deposited increases, heat transfer performance decreases, and thermal fatigue increases.

Further, it is simple in construction and easy to operate compared to other conventional annular combustor devices and systems, has low initial and maintenance costs for the device, and needs to be matched with multiple separate premixers. It is desired to provide a device with greatly improved controllability of the fuel / air ratio due to the lack of fuel.

[0011]

Means for Solving the Problems For example, US Pat. No. 5,377,
Experience with the development of low emission gas turbine combustors of the type described in No. 483 is desirable, depending on both the velocity of the fuel / air mixture exiting the premixer mixing tube and the composition of the fuel / air mixture itself. It turns out that no pulsating flow occurs. Overall, the shape of the combustor affects the nitrogen oxide emissions. If the mixing tube outlet basin is fixed, the velocity of the exiting fuel / air mixture can differ by as much as three orders of magnitude between idling and full speed. In order to prevent undesired combustion (flashback) into the premixer and to reduce exhaust emissions, the minimum discharge rate must be well above the flame rate of the fuel used.

Typical fuel (eg diesel fuel # 2)
The desired minimum speed when using is about 20 to 30 m / sec. At this speed, the thickness of the boundary layer formed on the nozzle wall during operation is not large, and at low output levels such as idling, good performance of the combustor can be exhibited with almost no flashback. . However, at full speed, depending on the type of turbine engine, the velocity ejected from the nozzle can be as high as 100 m / sec in the case of a fixed outlet basin. At such high speeds, it is difficult to maintain flame stability and the fuel / air mixture stream impacts the adjacent combustor liner walls.

In accordance with the invention as specifically and broadly described herein, a premixer device for mixing fuel and compressed air from respective sources to deliver a fuel / air mixture to a combustor is a) a mixing tube having an inlet for the structure for introducing fuel and compressed air, an axis and an outlet for the structure for delivering a fuel / air mixture to the combustor, and (b) a fuel for delivering to the combustor. / A mixing valve associated with the mixing tube outlet to change the velocity of the air mixture.

[0014] Preferably, the premixer comprises a compressed air flow passage between the compressed air supply source and the mixing pipe inlet, a fuel flow passage between the fuel supply source and the mixing pipe inlet, and the fuel / fuel mixture. An air valve and a fuel valve disposed in each flow path for controlling a fuel / air ratio of the air mixture, the mixing valve varying the outlet velocity of the controlled fuel / air ratio mixture. Is characterized by.

Further preferably, the mixing valve has a mixing pipe outlet member and a valve member which is disposed adjacent to the mixing pipe outlet member and forms an outlet flow region together with the outlet member. One of the valve member and the outlet member is movable relative to the other along the mixing tube axis to change the speed.

More preferably, the outlet member is a nozzle assembly fixed to the mixing tube and the valve member coaxially surrounds the nozzle assembly about the mixing tube axis and has a skirt portion having a skirt end. Wherein the skirt end and the nozzle assembly form a cylindrical annular outlet flow area, during relative movement of the skirt end and the nozzle assembly,
The basin and the mixture velocity vary with the relative axial position of the skirt end and the nozzle assembly.

The outlet member is an axial end of the mixing tube, the valve member is a valve plate, the axial end of the mixing tube and the valve plate form a cylindrical annular outlet flow area, During relative movement between the valve plate and the axial end of the mixing tube,
The basin and the mixture velocity vary with the axial relative position of the axial ends of the valve plate and the mixing tube.

More preferably, the device comprises a sensor for detecting the pressure of the mixture upstream of the mixing pipe outlet, an actuator operatively connected to one of the mixing valve member and the mixing pipe outlet member, and a detection pressure. A controller operatively connected to the pressure sensor and the actuator for varying the mixing tube flow outlet flow region and the mixture outlet velocity accordingly.

According to the invention, the exhaust from a premixer device having a fuel / air mixing tube with an inlet in communication with the fuel supply and the compressed air supply, an axis and an outlet for discharging the fuel / air mixture. (1) a mixing valve having a mixing pipe outlet member and a valve member forming an outlet flow region together with the mixing valve; and (2) the valve member and the mixing pipe. The outlet basin is increased or decreased by moving one of the outlet members relative to the other, thereby slowing or increasing the velocity of the fuel / air mixture.

Further in accordance with the present invention, a gas generator for a gas turbine operable with a fuel supply source is an air compressor, a turbine, a shaft assembly connecting the air compressor and the turbine, and a combustion to the turbine. A gas generator for a gas turbine comprising a combustor operably connected to deliver gas and one or more premixers, each of the premixers comprising (1) a fuel / air mixture. A mixing tube having an inlet for receiving fuel coming from a fuel source and compressed air coming from the air compressor for generation, an axis, and an outlet configured to deliver the fuel / air mixture to the combustor. When,
(2) It is characterized by having a mixing valve interlocked with the mixing pipe outlet in order to change the speed of the fuel / air mixture fed to the combustor.

Further in accordance with the present invention, a gas generator for a gas turbine (a compressor for delivering compressed air along a flow path, a fuel tube connectable to a fuel source, and a fuel / air mixture). And a mixture tube having an inlet in communication with the compressed air flow path and the fuel tube and an outlet in communication with the combustor) to control the flow of the fuel / air mixture to the combustor. ) Using the respective compressed air flow path upstream of the mixing tube inlet and the respective valves located in the fuel tube, the compressed air to the mixing tube inlet to obtain a mixture having a desired fuel / air ratio; Controlling the flow rate of the fuel, and (2) controlling the velocity of a fuel / air mixture having a desired fuel / air ratio flowing in the mixing tube outlet using a mixing valve located in the combustor. Is characterized by.

Some of the advantages of the present invention are described herein, and other advantages will be apparent from such a description upon understanding the invention. The advantages of the invention will also be apparent from the drawings and the appended claims.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described with reference to the accompanying drawings. Specifically, the embodiment of the present invention is shown in FIGS.
Shown in. 16-20 show a gas turbine engine having a premixer with a variable geometry to control the outlet velocity of the mixture. Also, a reading of the relevant pre-stage gas turbine engine and premixer combustor system readings will enable a better understanding and application of the present invention.

Referring first to FIG. 1A, there is shown a pre-stage combustor system having the features of the present invention, indicated generally by the reference numeral 10. The illustrated system 10 is for use with a radial gas turbine engine module 12. The gas turbine engine module 12 has a pressure housing 14 having a shaft 16 mounted therein that is rotatable about an axis 18. The radial turbine 20 is attached to one end of the shaft 16,
Drives a centrifugal compressor 22 attached to the other end of the shaft 16. In the structure shown in FIG. 1A, the output of the gas turbine engine module 12 is taken from a mechanical coupling device (generally indicated at 24) proximate the centrifugal compressor 22. However, similar to the configuration shown in FIG. 1A, the combustor system of the present invention, as one of ordinary skill in the art will readily appreciate, may, for example, be a “free power turbine” (see FIG. 5A), a “free jet” propulsion unit (see FIG. It may also be used in a gas generator in combination with other turbine engine systems (not shown). Further, the present invention is not limited to use in a radial gas turbine engine or a gas generator module, and is used with an axial turbine engine module, an axial-radial mixed turbine engine module and a gas generator module in at least the broadest sense. You can also do it.

Still referring to FIG. 1A, the gas turbine engine module 12 generally operates as follows. The air introduced into the centrifugal compressor 22 in the direction indicated by the arrow 26 is accelerated by the centrifugal force and enters the diffuser 28 to increase the static pressure. Compressed air exiting diffuser 28 is collected in plenum chamber 30 and then plenum 30.
The compressed air from the pre-mixer 60 of the combustor system 10
Are mixed with fuel coming from the fuel supply source 32 (details will be described later) and burned to generate high-temperature exhaust gas. The hot exhaust gas flows into the radial turbine 20 via the inlet guide vanes 34, where the output is obtained. Turbine
The exhaust gas emitted from 20 is discharged to the atmosphere or sent to the engine module in the subsequent stage. In the case of a free power turbine arrangement, the gas exiting turbine 20 is delivered to the free power turbine for even greater power output.

The combustor system shown in FIG. 1A has a cylindrical housing that defines a combustion chamber, the housing having an axis and at least one intake port proximate one axial end of the chamber. It is important that there is a single-stage combustion zone at one end of the chamber in the axial direction. The exhaust portion is located at the other end of the chamber in the axial direction, and the combustion chamber portion adjacent to the other end of the chamber in the axial direction has a dilution zone. The housing further comprises opening means in the form of a dilution port which communicates with the dilution zone.

As shown in FIG. 1A, the combustor system 10 includes
Substantially toroidal annular combustor liner housing 40
(Referred to simply as "housing" or "liner"). Although an annular housing is also shown in FIG. 1A, a “can” cylindrical housing can also be used. The housing 40 is within the pressure vessel 14 and its axis 42 substantially coincides with the axis 18 of the gas turbine engine module. The housing 40 is closed at the axial end 44 except for the intake port 43, but is open at the axial end 46 to form an annular exhaust port 48 (combustor outlet). Exhaust port
48 communicates with radial turbine 20 via channel 50 and inlet guide vanes 34.

Further in FIG. 1A, the toroidal chamber 52 formed by the housing 40 has two generally axial sections with different effects. Section 54 adjacent axial end 44 forms a single stage combustion zone and section 56 adjacent housing end 46 forms a dilution zone. A plurality of openings 58a, 58b are provided in the housing 40 opening to the dilution area 56. With respect to the housing axis 42, the dilution port 58a is a series of openings formed in the outer peripheral surface of the housing 40, and the dilution port 58b
Is a series of openings formed in the inner peripheral surface of the housing 40. The opening means, generally having dilution ports 58a and 58b, is a compressed air conduit means (described in more detail below).
The compressed air coming from is introduced into the dilution zone 56 of the combustion chamber 52. However, it is not necessary to provide the dilution opening on both the inner and outer walls of the combustor liner, and if the opening 58b having a size adapted to the total flow rate of the dilution air is used, the opening 58a can be formed.
May be omitted.

At least one fuel / air premixer located outside the cylindrical housing mixes a portion of the compressed air stream with fuel to produce a fuel / air mixture, which mixture is passed through an intake port to a combustion zone. To send. The fuel / air premixer has compressed air intake means, fuel intake means, and chamber means for smoothing the flow of the intake compressed air and mixing the intake compressed air with fuel. Referring to FIG. 1A, combustor system 10 further includes a single fuel / air premixer, generally indicated by the reference numeral 60. The premixer 60 has a housing assembly 62 that draws compressed air from conduit means, described in detail below, and a single fuel nozzle 64 that draws fuel from a fuel source 32 through a fuel line 66. The fuel nozzle 64 shown in FIG.
An "airblast" type fuel nozzle that is particularly advantageous for promoting atomization and vaporization when used with liquid fuels. However, the use of "air blast" type nozzles for gaseous fuels has the advantage of premixing the fuel with air prior to feeding the venturi means described below. Therefore, similar to the present invention, the combustor system of FIG. 1A is not limited to the use of liquid fuel or air blast fuel nozzles, but other types of fuel nozzles such as gaseous fuel and swirl nozzles can also be used. .

The fuel / air premixer 60 further includes a fuel / air premixer 60.
It has a mixing chamber means in the form of a venturi 68 having a venturi inlet 70 located within the air premixer housing assembly 62 and a venturi outlet 72 connected to the suction port 43. Venturi 68 has a flow axis 74 and fuel nozzle 64 is positioned to deliver a fuel spray to venturi inlet 70 substantially along axis 74. Venturi is used to vigorously and thoroughly mix the fuel and compressed air in the venturi chamber and to direct the fuel / air mixture along the venturi axis 74 to the combustion zone 54 as shown schematically by arrow 76.
Select 68 channel cross-sections and dimensions. Venturi outlet so that the minimum velocity of the fuel / air mixture (the velocity at idling) is greater than the flame propagation velocity of the fuel / air mixture.
72 watersheds must be selected. In order to improve the stability of combustion within the combustion zone 54, flame holding means, such as schematically indicated by reference numeral 78, may be provided near the venturi outlet 72.

As best shown in FIG. 1B, the admixed venturi 68 is positioned so that the venturi axis 74 is substantially tangential to the housing axis 42 so that the intake fuel / air mixture is Swirls around axis 42 in combustion zone 54. As can be seen from the preferred premixer construction described in more detail below, only a single fuel / air premixer fed by a single fuel nozzle is used to properly deliver the fuel / air mixture to the combustion chamber 52. be able to. Multiple fuel / air premixers may be used, especially when the radial "thickness" of the combustion chamber 52 (measured from axis 42) is small relative to its outer diameter, as shown in FIGS. 1A and 1B. .

The combustor system has an igniter located on the cylindrical liner housing near the intersection of the venturi flow axes. In FIG. 1B, the igniter 79 is located near the intersection of the flow axis 74 and the liner housing 40 and extends a short distance into the combustion zone 54. Therefore, ideally, the igniter 79 should be premixed to initiate combustion.
Located to intersect the fuel / air mixture exiting 60. Once combustion is initiated, the hot combustion gases that swirl within the combustion zone 54 autoignite the fuel / air mixture and the ignition device.
79 (electrical) normally stops.

In the pre-combustor system, compressed air conduit means is provided for connecting the compressor outlet to the fuel / air premixer and delivers a portion of the compressed air flow to the compressed air intake means of the premixer. , Delivering substantially the remainder of the compressed air stream to the opening means and delivering dilution air to the dilution zone. Further in FIG. 1A, reference numbers
The compressed air conduit means, indicated generally by 80, has a generally annular flow passage 82 disposed between the pressure housing 14 and the housing 40. The flow path 82 extends between the compressed air intake plenum 30 and the ring-shaped plenum 84 and is formed as part of the pressure vessel 14 proximate the exhaust section of the turbine. As mentioned above, the fuel / air premixer housing assembly 62 is coupled to draw compressed air from the plenum 84 and deliver it to the venturi inlet 70. Although the illustrated plenum 84 has an annular cross-section, other shapes and positions are possible and within the scope of the invention.

As is apparent from the schematic view of FIG. 1A, the flow path 82
The flow path 82 is configured so that the compressed air flowing through it cools the housing 40, particularly the portion 86 of the housing that directly surrounds the combustion zone 54 where the highest combustion temperature is expected.
Portion 86 of housing 40 need only be convectively cooled and need not be film cooled. That is, the portion 86 of the housing 40.
Serves to isolate the compressed air flowing in the flow path 82 from the fuel / air mixture burning in the combustion zone 54. Because of this structure, the fuel / air ratio of the mixture can be controlled in the combustion zone 54 and can operate as a "single-stage combustor" with the desired lean fuel / air ratio. By such an operation, the emission amounts of NOx, unburned fuel and combustion by-products can be reduced. As discussed below, the unique construction of the combustor system results in very low levels of NOx when compared to other conventional combustor systems.

The flow path 82 substantially surrounds the combustion chamber 52 and provides convection cooling and supplies compressed air to the dilution ports 58a and 58b. As shown in FIG. 1A, the flow path 82 may also have channels 82a that direct a stream of compressed air to cool the portion of the pressure vessel 14 proximate the turbine 20. The turbine inlet guide vanes 34 may be film cooled inlet guide vanes and may also be supplied with compressed air from the flow passages 82 or 82a. The compressed air conduit means 80 may also have a separate flow passage 88 connecting the compressed air intake plenum 30 and the air blast fuel nozzle 64, especially when using the air blast fuel nozzle 64 with liquid fuel.

As will be apparent from the above description in connection with FIG. 1A, the compressed air conduit means 80 directs a portion of the compressed air stream to the fuel / air premixer 60, while leaving a substantial portion of the compressed air stream to the dilution port. Lead to 58a and 58b. The compressed air flow that is not directed to either the fuel / air premixer or the dilution port (ie, the air used to cool the inlet guide vanes 34) is very small and in any case the fuel / air ratio in the combustion zone. Does not disturb the exhaust gas and only slightly dilutes the exhaust gas before entering the turbine 20.

Further, in order to determine the flow rate of compressed air supplied to the premixer, valve means is arranged in the compressed air flow path. The compressed air valve means is particularly important when the speed of the compressor (and thus the volumetric flow rate of compressed air) is largely independent of the fuel flow rate, as in the application shown in FIG. 1A. A valve 90 is provided in the fuel / air premixer housing assembly 62 to define the flow rate of compressed air from the plenum 84 into the venturi inlet 70, as described herein (see FIG. 1A). Has been. The valve 90 is continuously adjustable and suitable constructions of the valve 90 are discussed in more detail below in connection with the description of the preferred construction of the fuel / air premixer of the present invention. When the opening of the valve changes, the pressure drop by the premixer changes, and the flow rate of air to the dilution zone increases or decreases. Thus, air flow changes and splits occur outside the combustor.

FIG. 2 shows a combustor system 110 having an alternative form of compressed air conduit means. A component having the same or similar operation as the embodiment of FIGS. 1A and 1B has "100".
The same reference number is given except that it starts with. In the compressed air conduit means generally indicated at 180 in FIG. 2, a distribution conduit 181 is provided between the compressed air collection plenum 130 and an annular flow passage 182 surrounding the housing 140,
The fuel / air premixer housing assembly 162 has a flow path 182.
It is directly connected to the distribution conduit 181 upstream of. A valve 190 is provided at the connection between the fuel / air premixer housing assembly 162 and the distribution conduit 181 to direct the air flow to the fuel / air premixer 160 and the branch conduit portion.
It is divided into the remainder flowing through the flow path 182 via 181a. Figure 1A
Of the fuel / air premixer, where substantially all of the compressed air entering the premixer is first used to cool at least a portion of the liner housing portion 86 forming the combustion chamber 52. Any part of the compressed air entering 160 will form a combustion zone 152
Not used to cool 140 parts 186. However, the embodiment of FIG. 2 allows direct control of the portion of compressed air entering the fuel / air premixer with respect to the portion of compressed air flow entering dilution ports 158a and 158b. Nevertheless, the shape shown in FIG. 1A is easier to assemble the various components, primarily the fuel / air premixer (discussed in detail below), which allows the valve to be directly integrated with the fuel / air premixer housing. Can be said to be preferable.

Further, in the pre-combustor system, fuel conduit means is provided for connecting the fuel supply to the premixer fuel intake means. The fuel conduit means forms with the premixer fuel intake means a flow path for all fuel entering the premixer. Fuel valve means is disposed within the fuel flow path for determining the flow rate of fuel through the fuel conduit means. Referring again to FIG. 1A, fuel line 66 connects fuel supply 32 to fuel nozzle 64. Fuel valve 92 is the fuel line
It is arranged at a position immediately upstream of the fuel nozzle 64 among 66. Fuel nozzle 64 is shown as an "air blast" type fuel nozzle that is particularly suitable for use with liquid fuels as described above.

Further, the combustor system of FIGS. 1A and 1B
Compressed air valve means and fuel for substantially controlling the respective flow rates of the compressed air portion and fuel delivered to the premixer to deliver a predetermined lean fuel / air ratio mixture from the intake port to the combustion zone. It has control means operatively connected to both of the valve means. As shown schematically in FIG. 1A, a controller 94, which may be mechanical or electrical (eg, microprocessor), is coupled to the compressed air valve 90 to substantially control the flow rate of compressed air entering the venturi inlet 70. Control. When using an "air blast" nozzle, a small portion (typically 5% or less) of the total compressed air entering fuel / air premixer 60 may pass through conduit 88, but the remainder of the compressed air flow. If (90% or more) is controlled by the valve 90, the total fuel / air ratio can be expected to be controlled appropriately. Further, when using a gaseous fuel such as natural gas as shown in the following example, the conduit 88 may be omitted and all of the compressed air flow entering the fuel / air premixer controlled by a compressed air flow valve. You can

Further, as shown in FIG. 1A, the controller 94 is connected to the fuel valve 92 and measures the flow rate of the fuel flowing into the fuel nozzle 64. As will be appreciated by those skilled in the art, the controller 94
By controlling both the fuel flow and the compressed air flow into the fuel / air premixer 60 at a constant fuel / air ratio during the entire operating period of the gas turbine engine module, thus increasing the flow rate of the combustible mixture to the load. It can be changed as a function. Alternatively, the controller 94 can be configured such that a set of predetermined fuel / air ratios is a function of load. A person skilled in the art can appropriately adopt a controller suitable for a specific application based on the description in this specification and known knowledge.

1A and 1B, during operation, the compressed air coming from the compressed air suction means 30 is guided to the outer surface of the housing 40 through the flow path (enclosure) 82, and the housing 40 (particularly the combustion area 54 Cool the part 86) surrounding the. A portion of the compressed air flowing in the flow path 82 enters the plenum 84, which is then controlled by the compressed air valve 90 controlled by the controller 94 to provide a connection between the fuel / air premixer housing assembly 62 and the plenum 84. It flows into the fuel / air premixer 60 via the connection.
In the venturi 68, a portion of the compressed air is mixed with fuel exiting the fuel nozzle 64 (along with a small additional portion of compressed air when the nozzle 64 is an "air blast" nozzle) and drawn along the venturi axis 74. It enters the combustion zone 54 of the combustion chamber 52 via the port 43.

Since the venturi axis 74 is tangential to the housing axis 42 as shown in FIG. 1B,
Spiral combustion occurs in the combustion zone 54. To provide aerodynamic unloading by the inlet guide vanes, the orientation of the venturi axis 74 is selected to be at a particular angle (clockwise or counterclockwise) with respect to the direction of turbine rotation. The shape shown in Fig. 1A and Fig. 1B (combustion area when viewed from direction AA)
Fuel / fuel to cause combustion that swirls clockwise in 54
Inhaling the air mixture), the direction of rotation of turbine 20 is also clockwise. The hot exhaust gas produced by the combustion of the fuel / air mixture in the combustion zone 54 flows into the dilution zone 56,
Turbine 20 through inlet guide vanes 34 through channel 50
It does its work by entering and expanding there, but before that the dilution air coming from the dilution ports 58a and 58b lowers the average temperature.

Control of combustion by the combustor system 10 of the present invention is accomplished by thoroughly mixing the fuel and air in a fuel / air premixer outside the combustion chamber,
When using a liquid fuel, to completely vaporize the fuel and control the fuel / air ratio of the mixture delivered to the combustion chamber to significantly reduce NOx levels and unburned fuel and combustion by-product levels as described above. You can Moreover, the use of substantially all of the compressed air stream to burn fuel upstream of the turbine or to dilute the exhaust gas significantly reduces the peak temperature of the combustor compared to conventional combustor construction, Therefore, the life of the combustor liner is extended.

As mentioned above, the fuel / air premixer of the structure shown in FIGS. 1A and 1B (and the preferred premixer of the present invention) is operative to the compressed air intake means and the compressed air intake means having the air flow smoothing means. A venturi having an inlet connected to the venturi, a fuel intake means having a nozzle positioned to deliver a fuel spray to the venturi inlet substantially along the axis of the venturi, and a fuel intake means associated with the compressed air intake means. Valve means for determining the flow rate of compressed air entering the venturi inlet. Referring to FIG. 3A, the fuel / air premixer 260 has air intake means in the form of a housing assembly 262. Components having similar functions to those of the embodiment of FIGS. 1A and 1B are designated by the same reference numeral of 200 units. Housing assembly 262 is housing 300
And the pressure vessel 21 of the gas turbine engine module 212
4 has a housing support 302 for mounting the housing 300. The housing support 302 is hollow and, in addition to supporting the housing 300 and the components contained therein, serves to direct compressed air from the plenum 284 to the housing 300. In the structure shown in FIG. 3A, the cooling shroud member 303 is located between the combustion chamber liner housing 240 and the pressure vessel 214 and has a flow passage 282 at least near the portion 286 of the housing 240 that bounds the combustion zone 254.
To form. The shroud member 303 also includes a pressure vessel 214.
Along with collecting some of the compressed air, the housing support 30
2 to form a plenum 284 for final delivery to the housing 300.

Still referring to FIG. 3A, the fuel / air premixer housing 300 is divided by a divider plate 308 into upstream and downstream compartments 304, 306, respectively. The dividing plate 308 has an opening 310, and the opening
A butterfly type valve plate 290 is rotatably mounted in 310. In the embodiment of FIG. 3A, the orientation of the valve plate 290 within the opening 310 is controlled by the control rod 312 (see FIG. 3B) to provide selective flow obstruction and thus pressure drop. It In the orientation of the valve plate 290 shown in FIGS. 3B and 3C, the valve plate 290 is oriented perpendicular to the divider plate 308.
The flow obstruction is minimized (corresponding to the zero setting of the angle calibration plate 314 shown in FIG. 3C). When the position of the control rod 312 corresponds to both positions 9 on the indicator 314, there is maximum flow obstruction and pressure drop in the compressed air portion flowing through the opening 310. As will be appreciated by those skilled in the art, the degree of obstruction and thereby control of the compressed air flow between the upstream compartment 304 and the downstream compartment 306 is controlled by the control rod 312 between the zero position and position 9.
Can be done by changing the angle of
The flow rate of compressed air can be controlled at the balance point of the air premixer 260 (details will be described later).

The dividing plate 308 is an inlet 270 of the venturi 268.
Has an additional opening 316 in which is attached. The venturi inlet 270 is configured and attached to the divider plate 308 so that the flat upper surface of the divider plate 308 and the inner surface of the venturi inlet 270 are smoothly connected. Venturi 268
Includes an upstream housing compartment 304, a housing support 302, a pressure vessel 214 and a combustor chamber liner.
Extends through 303, housing at intake port 243
It is connected to 240. As described above with respect to the embodiment shown in FIG. 1A, the venturi axis 274 substantially corresponding to the direction of flow of the fuel / air mixture within the venturi 268 is substantially relative to the axis of the annular combustion chamber housing 240 (not shown). Oriented tangentially to.

Still referring to FIG. 3A, fuel nozzle 264 is mounted in downstream compartment 306 and fuel nozzle outlet 318 is positioned to deliver fuel spray to venturi inlet 270 along venturi axis 274.
Fuel nozzle 264 is a swirl spray type that uses port 320 and swirl vanes 322 to introduce a portion of the compressed air before swirling fuel spray through outlet 318 and swirl the fuel entering through fuel port 324. The flow smoothing porous member 326 shown in FIG. 3A is also located within the downstream compartment 306,
Surrounds fuel nozzle outlet 318 and venturi inlet 270 to prevent uneven velocity and separation within the venturi (otherwise flame retention within the venturi). Perforated member 326
With a slight pressure drop, the compressed air flow from the downstream compartment 306, through the fuel nozzle 264, and into the venturi inlet 270 causes the venturi inlet 27
It was found that the lip of 0 was stabilized without separation.

FIG. 4 illustrates the preferred fuel / fuel shown in FIGS. 3A-3C.
A commercial modification of the air premixer (generally designated by reference numeral 360) is shown. Components having the same or similar performance as described with respect to the embodiment of FIGS.1A and 1B are 30
Indicated by the same reference numbers starting with 0. The fuel / air premixer 360 has a venturi 368 with an inlet 370 extending slightly above the surface of the divider plate 408. The fuel nozzle outlet 418 also extends into the venturi inlet 370.
The optimum performance of the fuel nozzle 364 is determined by the venturi 368 (and also the nozzle 264 and the venturi in the modification shown in FIGS. 3A-3C).
268) and may vary from application to application, and one skilled in the art will be able to adjust the fuel nozzle outlet 418 near the venturi inlet 370 along the venturi axis 374 to an optimal position. Easy to understand. Figure 4
Also in this embodiment, the use of the perforated screen member 426 stabilizes the flow. The embodiment shown in FIG. 4 uses an integral bell-shaped housing 400 and is a modification of the fuel / air premixer construction comparable to the construction shown in FIG. 3A.

As noted above, the benefits of the present invention can be utilized in applications such as gas turbine gas generator modules for use with free power turbines or free jet propulsion units. This gas generator does not require a compressed air flow valve and its associated control means. Figure
5A schematically illustrates a pre-combustor system (generally designated by reference numeral 500) constructed in accordance with the present invention. Engine 50
0 has a gas turbine gas generator module 512 comprising a combustor system 510 described below and a free power turbine module 513. The free turbine module 513 has a free turbine 513a, which is shown as an axial turbine,
Depending on the application, either a radial turbine or an axial-radial mixed type turbine may be used. In contrast to the engine system of the embodiment of FIG. 1A (where power is taken from gear means 24 coupled to shaft 16), the embodiment of FIG. 5A uses engine means 500 to output power through gear means associated with free turbine shaft 513b. Take from Gas Generator Module Axis 518
Although shown coaxially, the rotational axis 513c of the free power turbine 513 may be tilted to meet the requirements of the overall system 500.

In the following description, components similar to the embodiment of FIG. 1A are designated by the same reference numbers, for example starting with 500 units.

Specifically, the gas turbine gas generator module 512 includes a pressure housing 514 for rotation on a mechanically independent spool or shaft 516.
It has a centrifugal compressor 522 and a radial turbine 520 provided therein. Therefore, although the gas generator 512 and the free turbine module 513 are connected in the gas flow cycle, the shaft 516 can rotate independently of the free turbine shaft 513b. Module 512 also includes combustor system 51 having combustor liner housing 540.
And a combustor liner housing 540 is contained within the pressure housing 514 and draws the fuel / air premix from the external premixer 560 along the venturi axis 574 through the inlet port 543. As previously described with respect to Figure 1A, the Venturi shaft 574 is an annular combustor liner housing.
Oriented tangential to axis 542 of 540,
Efficient swirl combustion occurs and the inlet guide vane
Partly unload 534 (see Figure 5B).

FIG. 5B also shows the preferred position of the ignition device 579,
That is, the position on the liner housing 540 near the intersection with the Venturi axis 574. Placing the igniter in a relatively cool environment, such as in a premixer, prolongs the life of the igniter and increases the liner housing 540
While reducing the number of components penetrating in, it is useful when the arrangement shown in FIG. 5B requires reliable light-off due to the slow fuel / air mixture in the annular chamber.

In the embodiment shown in FIGS. 5A and 5B, liner housing 540 and pressure housing 514 form a flow path for compressed air flow coming from compressor plenum 530. The engine of this embodiment also includes an annular cooling shroud 583 disposed between the liner housing 540 and a portion of the pressure housing 514 proximate the outer periphery thereof and radially spaced therefrom. As you can see, the cooling shroud 583 and liner housing 540
It forms part of the flow path 582 for convectively cooling the combustor chamber formed by the liner 540. Cooling shroud 583 and pressure housing 514, on the other hand, form an annular plenum 584 for collecting the portion of the compressed air stream to be introduced into premixer 560 for mixing with fuel. Figure
In the 5A embodiment, similar to the embodiment of FIG. 1A, some of the compressed air is removed from the flow path communicating with the compressor outlet after convection cooling and then introduced into the premixer for mixing with fuel. However, the device of FIG. 5A can be structurally much more compact than the ring plenum 84 of FIG. 1A. In addition, the cooling shroud 583 shields radiant heat from the relatively hot liner housing 540 to the adjacent portion of the pressure housing 514, allowing the use of relatively inexpensive materials for the pressure housing and extending its life. be able to.

The remainder of the compressed air flow in the channel 582 is the dilution hole 55.
Pass 8b. Although there is no dilution port corresponding to port 58a in the embodiment of FIG. 1A, dilution port 558b has two spaced apart annular ports 558b ₁ and 558b ₂ . Divider 559 and port
Due to the setting of the dimensions of 558b ₁ and 558b ₂ , the dilution air that has passed through the port 558b ₂ first flows through the turbine shroud 557 and the flow path 582a. One of ordinary skill in the art can perform dimensional analysis to properly distribute the dilution air to achieve the desired turbine shroud cooling. As mentioned above, the ability to control the fuel / air ratio within the combustion zone 554 due to the lack of film cooling is an important advantage of the present invention.

FIG. 5A illustrates the use of an "air blast" type liquid fuel nozzle, but for the reasons discussed above, a conduit extending from the compressor outlet plenum 530 to the premixer 560.
588 is shown with a dotted line. In FIG. 5A, the through compressor plenum outlet 530 is shown slanted axially for clarity, but the full dynamic head (dynamic
The inlet to conduit 588 to obtain the head) is tangential to the compressor outlet and in the axial plane. A person skilled in the art can design an appropriate inlet shape from the description in this specification.

To operate air blast liquid fuel nozzles (and possibly to cool inlet guide vanes)
Apart from the small amount of compressed air required for
Used to convectively cool at least a portion of the liner housing 540 prior to use for mixing with fuel or for dilution. This structure optimizes the convective cooling capacity of the compressed air. Although not shown, the present invention also includes a gas generator embodiment corresponding to the embodiment of FIG. 2 (where the compressed air portion used to mix with the fuel is not initially used for convective cooling). . The simple construction of such a system more than compensates for the reduced cooling capacity and is therefore desirable for some applications.

As shown in FIG. 5A, the air is premixer 560.
Channel 582 is introduced into annular plenum 584 for direct mixing therewith with fuel. 5A shows the compressed air valve 590 in dashed lines because the valve 590 is an optional component. The compressed air valve 590 can be used to “fine tune” the fuel / air ratio during operation, but it can also be preset to a fixed opening during operation or removed altogether for the following reasons: it can. Engine system 510
Thus, the speed of the compressor 522, and thus the flow rate of compressed air, is approximately proportional to the flow rate of fuel over the entire operating range, and the fuel / air ratio can be automatically controlled to a predetermined lean value. Thus, the operation of the controller 594, which controls the flow of fuel from the fuel supply 532 to the fuel nozzle 564 through the fuel valve 592, is similar to that of a conventional throttle controller responsive to power demand.

Premixer 560 burns all fuel / air mixture required during a given period of operation of engine system 510.
However, an auxiliary refueling system such as system 596 shown in FIG. 5B may be used to deliver a high fuel ratio mixture at start-up and idling conditions. System 596 has a conventional fuel spray nozzle 597 powered by a fuel source 532 (see FIG. 5A),
The flow rate of auxiliary fuel can be controlled by controller 594 via valve 598. In the disclosed construction, the spray nozzle 597 is arranged to project radially into the liner housing 540 proximate the venturi outlet 572. However, the nozzle 597 may be positioned tangentially opposite the Venturi 570 (not shown) to provide better mixing with the fuel / air mixture entering through the Venturi 570. Of course, it is possible and within the scope of the invention to vary the position, structure and orientation of the spray nozzle 597.

FIG. 6 schematically illustrates a "valveless" premixer structure (generally designated by reference numeral 660) that can be used in engine system 510. The premixer 660 includes a housing 662, a fuel nozzle 663 of the type having a peripheral spiral vane 665, and a venturi 668 having an axis 674 tangential to the axis of the combustor (not shown). Also, the flow smoothing porous member 667 surrounds the inlets of the nozzle 664 and the venturi 668 for the reasons described above in connection with the corresponding components in the "valve" embodiment of FIG. 3A. The premixer 660 also includes heating means, such as an electrical resistance heater jacket 669, surrounding the throat of the venturi 668 and connected to a power source (not shown) via leads 671. During start-up and use of liquid fuel, a thin film of fuel tends to accumulate on the inner surface of the Venturi. The heater jacket 669 enhances the vaporization of this thin film of fuel and enhances the mixing of fuel and air in the premixer. During operation, the temperature of the compressed air portion flowing from the plenum 684 to the outer surface of the Venturi 668 provides sufficient heat to vaporize the liquid fuel or completely prevents the formation of a thin film of liquid fuel, so that the heater jacket 669 is continuous. There is no need to activate it.

FIG. 7 illustrates yet another embodiment of an engine structure (ie, a gas turbine such as that described in US Pat. No. 5,081,832, which is a part of this specification) in which the combustor of the present invention may be beneficially utilized. 1 schematically shows an engine system). In FIG. 7, the engine system 700 is a high pressure spool.
711 and a mechanically independent low pressure spool 709. The low pressure spool 709 is connected to the shaft 70 by the low pressure turbine 703.
Includes a low pressure compressor 701 driven via 2. Compressed air flowing out of the low pressure compressor 701 flows through the diffuser 704 and is further compressed for further compression.
Inflow to 722. As a component of the high pressure spool 711,
High pressure compressor 722 is driven by high pressure turbine 720 via shaft 716. The gas discharged from the high-pressure turbine 720 is diffused in the diffuser 705 and expanded in the low-pressure turbine 703. For reasons fully explained in US Pat. No. 5,081,832, the output of the net is obtained from the engine system 700 via a gearing 724 connected to the shaft 716 of the high pressure spool 711. Low pressure spool 7
09 is primarily used to deliver precompressed air to high pressure spool 711, but can also be used to drive engine support systems (eg, lubrication members).

As is apparent from FIG. 7, the engine system 700 has a combustor system 710 and a high pressure compressor.
The high temperature combustion gas is delivered to the high pressure turbine 720 by combusting the fuel with a portion of the compressed air coming from the 722. The combustor system 710 uses an external premixer 760, which may be an “air blast” type that draws compressed air directly from a compressor 722 via a fuel nozzle 764 (a conduit 788 with a tangential inlet shown in phantom). When,
Annular combustion zone 75 formed by liner housing 740
4 has a venturi 768 for tangentially delivering the fuel / air premix. The cooling shroud 783 and liner housing 740 form part of a convection cooling flow path 782, and the circumferentially adjacent portion of the cooling shroud 783 and pressure housing 714 is an annular plenum for delivering a portion of compressed air to the premixer 760. Form 784. The rest of the compressed air flow is
A structure similar to that shown in 5A is used for additional convection cooling and final dilution.

However, the engine system shown in FIG. 7 is for obtaining output at a substantially constant high-pressure spool shaft speed, and like the embodiment of FIG. 1A, the total compressed air flow rate is the gas generation of the embodiment of FIG. 5A. It is not automatically adjusted for different fuel flow rates like the Fuel Module 512. as a result,
The combustor system 710 specifically includes a compressed air valve 790 integrated with the premixer 760, which under control of the controller 794 controls the fuel valve 792 to achieve a predetermined lean fuel / air ratio. Although not shown, the embodiment of FIG. 7 may include features of other embodiments (igniter mounted on liner, auxiliary fuel spray system, staged dilution port, etc.).

FIG. 8 schematically illustrates yet another example of an engine in which it may be advantageous to utilize the features of the present invention. In FIG. 8, the combustor system is indicated generally by the reference numeral 810.
(As with some other figures, the top of combustor system 810 is broken away, showing a cross-section of the top half of the system.)
System 810 is used with radial gas turbine engine module 812. The gas turbine engine module 812 includes a pressure housing 814 in which is mounted a shaft assembly 816 that is rotatable about an axis 818. A radial turbine 820 that drives a centrifugal compressor 822 is attached to one end of the shaft assembly 816, and the centrifugal compressor 822 is attached to the other end of the shaft assembly 816. Figure 8
In the structure shown in, the gas turbine engine module 812
Output is taken from a mechanical coupling device (generally designated 824) adjacent to centrifugal compressor 822. However, the combustor system of the present invention may be used in, for example, "free power turbine", "free jet" propulsion units, and other gas generators within turbine engine systems readily apparent to one of ordinary skill in the art. The present invention is also not limited to use in a radial gas turbine engine or gas generator module, but may be used, at least in its broadest sense, with an axial or axial-radial mixed turbine engine as well as a gas generator module. it can.

Still referring to FIG. 8, the gas turbine engine module 812 generally operates as follows. Arrow
Air enters the centrifugal compressor 822 in the direction indicated by 826,
Accelerated by centrifugal force, it enters diffuser 828 and increases static pressure. The compressed air exiting diffuser 828 is collected in plenum 830. A portion of the compressed air coming from the plenum 830 is then mixed with fuel coming from the fuel source 832 by the premixer assembly 860 of the combustor system 810 to produce hot exhaust gas, as described in detail below, and exhaust gas. Radial turbine 820 via inlet guide vane 834
, Where the output is taken. Exhaust gas coming from turbine 820 is either exhausted to the atmosphere or delivered to subsequent engine modules. For example, in the case of a free power turbine system, the gas exiting turbine 820 is delivered to the free power turbine for additional power output.

The combustor system has a cylindrical combustor liner that defines a combustion chamber, the liner having an axis and one or more inlets (proximal to one axial end of the chamber). A portion of the chamber adjacent to one axial end has a single-stage combustion zone. Further in FIG. 8, the combustor system 810 is an annular combustor liner 84, which is generally toroidal in shape.
Has 0. The housing 840 is contained within the pressure vessel 814 and is located at the gas turbine engine module axis 818.
Has an axis 842 substantially coincident with. Liner 840 has entrance 8
It is closed at axial end 844 except 43, but is open at axial end 846, forming an annular combustor outlet 848. If multiple premixers are used, the liner may be provided with additional inlets to accommodate the additional premixers. Combustor outlet 848 is in communication with radial turbine 820 through channel 850 through inlet guide vanes 834.

Continuing with FIG. 8, the toroidal chamber 852 formed by the liner 840 has two generally axial sections with different effects. Region 85 adjacent axial end 844 forms a single stage combustion zone (eg, combustion volume) and region 85 adjacent liner end 846.
6 forms a dilution zone. Liner 84 with multiple ports 858
It is formed on the outer periphery of 0 and opens to the dilution area 856. Dilution port
858 introduces compressed air coming from a compressed air conduit (described in more detail below) into the dilution zone 856 of the combustion chamber 852. It also directs the compressed air coming from the premixer to the dilution zone through a second set of dilution ports (not shown) formed in the inner circumference of the liner 840 as a series of openings. You may pay.

Further, each of the one or more fuel / air premixer assemblies disposed against the cylindrical liner mixes a portion of the compressed air stream with the fuel to produce a fuel / air mixture, It is delivered to the combustion zone through each liner inlet. The fuel / air premixer assembly has an air inlet for sucking compressed air, a fuel inlet for sucking fuel, and a mixing tube for smoothing the flow of sucked compressed air and mixing the sucked compressed air and fuel. . Almost all air used during combustion is delivered to the combustion zone via one or more fuel / air premixer assemblies. The combustion zone is sealed so that it does not draw compressed air except through the premixer assembly.

8 and 8A, the combustor system 81
The 0 also has a single fuel / air premixer assembly, indicated generally by the reference numeral 860. Premixer assembly 86
0 indicates a housing assembly 862 that sucks compressed air from a conduit (described later) through an air inlet 861 and a fuel line 86.
It has a fuel nozzle 864 which sucks fuel from a fuel supply source 832 via a fuel inlet 865. The fuel nozzle 864 shown in Figure 8 is an "air blast" type fuel nozzle that mixes fuel with a swirl of compressed air and is particularly advantageous in promoting atomization and vaporization when used with liquid fuels. However, when using an "air blast" type nozzle for gaseous fuel,
There is the advantage of premixing the fuel with air prior to feeding the venturi member. Therefore, the combustor system of the present invention is not limited to the use of liquid fuel or air blast fuel nozzles, but other types of fuel nozzles such as gas fuel and swirl type nozzles can also be used. An auxiliary fuel nozzle 867 may be provided for use during start-up operation of the combustor system 810, as shown in FIG. 8A.

A mixing tube, such as a Venturi, is located at a flow axis oriented substantially radially with respect to the axis of the combustor liner, an inlet adjacent one axial end of the mixing tube, and the other axial end of the mixing tube. And a nozzle assembly. The mixing tube inlet is in communication with the air and fuel inlets of the premixer. The mixing tube is connected to the liner inlet and the nozzle assembly extends along the flow axis into the combustion chamber,
Deliver the fuel / air mixture into the combustion zone.

Further referring to FIG. 8, the premixer assembly 86
0 is also the fuel / air premixer housing assembly 86
2 has a mixing chamber in the form of a Venturi type mixing tube 868 having a mixing tube inlet 870 connected to the liner 840 at an inlet 843. In addition, mixing tube 868 provides a nozzle assembly 87 for delivering the fuel / air mixture to the combustion chamber (which is connected to the mixing tube portion extending into combustion zone 854).
Has two. Mixing tube 868 has a flow axis 874 and fuel nozzle 864 directs fuel substantially along axis 874 to the mixing tube inlet.
Located to spray within 870. Mixing tube 868 to obtain sufficient residence time to vaporize the fuel in the mixing tube and mix with the compressed air and deliver the resulting mixture flow to nozzle assembly 872 along mixing tube axis 874. Select the flow cross-sectional area and dimensions of. Preferably, the shortest residence time of the particulate matter in the mixing tube is, under high flow rate conditions in high power operation,
It should be on the order of 5-10 milliseconds. Due to the engine geometry such that the combustion air becomes hot, such a short residence time can prevent pre-ignition of the fuel / air mixture in the mixing tube. The preferred mixing tube shown in FIG. 8 is a Venturi type mixing tube 868, but those skilled in the art will appreciate that other geometric configurations are possible, such as conical or cylindrical mixing tubes.

Further, as shown in FIG. 8, the compressed air conduit has a generally annular cooling passage 882 disposed between the liner 840 and the second outer annular liner 841. Channel 88
2 extends between the compressed air plenum 830 and the dilution port 858. The fuel / air premixer housing assembly 862
It communicates with a mixing tube inlet 870 to receive compressed air from an orifice 885 in liner 841 and deliver the air through a plenum 884 and a valve 890 (discussed below).

As is clear from the schematic view of FIG. 8, the liner 840 is compressed by the compressed air flowing in the flow path 882.
The flow passage 882 is configured to cool the liner portion 886, which directly surrounds the combustion zone 854, in particular. liner
Portion 886 of 840 is configured to provide only convective cooling without film cooling. That is, part 88 of the liner 840
At 6, the liner isolates the compressed air flowing in flow path 882 from the fuel / air mixture that is burned in combustion zone 854. The flow path 882 surrounds the combustion chamber 852, provides convection cooling and delivers compressed air to the dilution port 858. This configuration allows the mixture fuel /
The air ratio is controlled to allow operation as a "single-stage combustor" at the desired lean fuel / air ratio. By such an operation, the emission amounts of NOx, unburned fuel and fuel by-products can be reduced.

As further shown in FIG. 8A, a valve 890 is located within the fuel / air premixer housing assembly 862 to determine the flow rate of compressed air from the plenum 884 to the mixing tube inlet 870. Valve 890 is continuously adjustable,
Although shown as a butterfly type, the structure of valve 890 may be modified as appropriate. When the opening degree of the valve changes, the pressure drop by the premixer also changes, and the air flow rate decreases or increases. A schematically shown controller 894 (eg, microprocessor) is connected to valve 890, and mixing tube inlet 87
It substantially controls the flow rate of the compressed air flowing directly into 0.
The controller 894 is also connected to the fuel valve and measures the fuel flow rate to the fuel nozzle 864. As will be appreciated by those skilled in the art, the controller 894 operates to control both the fuel flow and compressed air flow to the premixer assembly 860, thus providing a predetermined fuel / air ratio over the entire operating range of the gas turbine engine module. (Eg atmospheric conditions,
(Preselected depending on the operating conditions and the type of fuel) can be achieved. The controller 894 can change the fuel / air ratio steplessly or stepwise. One of ordinary skill in the art will be able to appropriately adapt the controller for a particular application based on the disclosure herein and the general knowledge in the art.

Referring to FIGS. 9-11, the nozzle assembly 872
Extend into the combustion chamber along the flow axis of the mixing tube and have one or more ports for delivering the fuel / air mixture into the combustion zone. The nozzle assembly further has at least one channel for each nozzle assembly port, wherein within each nozzle assembly port each channel is angled with respect to the flow axis of the mixing tube and the fuel / air mixture is within the combustion zone. End with a nozzle assembly port for delivering.

Specifically, the nozzle assembly 872 is located within the combustion chamber 852 and has a channel 901 formed by the geometry of the end cap 903 and the inner wall 905 of the nozzle assembly 872. The sidewall 905 can be formed as an extension for the mixing tube 868 and can have different geometric shapes. Nozzle assembly 872 also has an end cap 903 and a port 907 formed by sidewall 905. port
907 is in communication with channel 901 and delivers the fuel / air mixture within combustion zone 854. Side cap with end cap 903
Fins or ribs 909 are additionally provided to join the 905.

Because of the beveled or beveled surface of the nozzle assembly (and especially the channel 901), the flow of the fuel / air mixture, as indicated by the arrow in FIG.
Get away from. That is, the flow of the fuel / air mixture can be delivered in the desired direction by utilizing surfaces of various geometric orientations. Although several channels and nozzle assembly ports are shown, it will be appreciated that the objects of the invention can be achieved by utilizing only a single channel and its associated ports. However, at least two ports for delivering the fuel / air mixture in opposite angular directions with respect to the liner axis are particularly advantageous in utilizing the full combustion zone.

Furthermore, the nozzle assembly (and especially the channel)
The components of 901) can be configured to deliver the fuel / air mixture in various directions within the combustion zone without impacting the combustor liner wall. For example, nozzle assembly 872
Channel 901 can be configured such that the fuel / air mixture enters substantially radially or radially / axially (away from the flow axis of the mixing tube) of the combustion zone. Further, the flow may be delivered in a plurality of directions relative to the liner axis (eg, at least two substantially opposite directions substantially tangential to the axis of the combustion chamber liner as indicated by the arrows in FIG. 9). You can further,
As shown in FIGS. 10 and 11, the flow is changed with respect to the axis of the mixing tube 2
The channel 901 can also be configured to deliver in more than one direction.

Further, the nozzle assembly 87 having the above-described geometric shape is formed.
It can be seen from 2 that the flame holding effect is advantageously obtained by rapidly expanding and recirculating the fuel / air mixture in the vicinity of the end cap 903. That is, for example, the shape of the end cap 903 provides a region 911 for circulating the fuel / air mixture for combustion outside the nozzle assembly 872 proximate the port 907. Flame retention is advantageous in order to stabilize the flame near port 907 and thus maintain a stable flame tip to stabilize combustion during various operating conditions.

Accelerate the fuel / air mixture and burn the combustion chamber
To increase the velocity of the mixture delivered to the 852 relative to the velocity in the mixing tube 868, the total cross-sectional area of port 907 should be
About 70 to 90 of the cross-sectional area of 868 (generally indicated by reference numeral 913)
% Is preferable. The importance of this feature can be seen from the fact that if the fuel / air mixture flow rate is low relative to the flame velocity in the combustion zone 854, the flame coming from the chamber 852 may ignite the fuel in the mixing tube 868. By utilizing a port 907 sized to increase the flow rate of the fuel / air mixture, the flame coming from the combustion chamber 852 is less likely to "flash back" into the mixing tube. By increasing the flow velocity further, the boundary layer at port 907 along chamber 901 is reduced, thus allowing combustion chamber 85
It is believed that the flame coming from 2 crawls along the surface of the nozzle assembly 872, removing the low velocity region that flashes back into the mixing tube 868. In addition, the change in compressed air is
It is believed that the above geometries are particularly useful when they occur within 8 otherwise flame tip fluctuations or pulsations occur within the combustion chamber 852. Increasing the pressure at port 907 reduces the change in velocity of the compressed air in the premixer and reduces pulsation. These advantages are useful in maintaining the structural integrity of the combustor system and individual components, which is beneficial to the integrity and performance of the entire gas turbine engine itself.

FIG. 9A shows a modification of the structure shown in FIGS. 8 and 9, with the main difference that the premixer 860 'is a cylindrical air valve 890' instead of the butterfly air valve 890 and the asymmetric nozzle assembly 872 '. Is a point having. The air valve 890 'has a rotatable cylindrical inner section 890a' which gradually increases or decreases the degree of obstruction of the valve outlet opening 890c 'so that the cylinder / sleeve 890a' is Increases or decreases the air flow through valve 890 'as it rotates about axis 890b'. Those skilled in the art will recognize that other cylindrical valve structures can be used.

FIG. 9A also shows a nozzle assembly 872 ′ having asymmetric nozzle ports 907a ′ and 970b ′ configured to minimize the amount of fuel / air mixture impinging on the axial rear wall of liner 840. That is, due to the shape of the flow facing surfaces 901a 'and 901b' of the nozzle end cap 872a ', the fuel / air mixture is primarily dominated by the combustion chamber axis 84.
Enters combustion zone 854 tangential to 2 and some of the fuel / air mixture enters other areas (left and right of venturi axis 874 in Figure 9A). Such an asymmetrical arrangement of nozzle ports minimizes fuel / air mixture impingement on the liner wall, which can lead to carbon deposition, non-uniform heat transfer and increased strain due to thermal stress, while maintaining combustion. The volume can be used more effectively.

FIG. 9B is a modification of the structure shown in FIG. 9A, in which the cylindrical air valve 890 "is largely separated from the portion of the premixer housing 862 supporting the Venturi mixing tube 868. The air valve 890" is The large separation from the premixer housing not only helps reduce the inevitable asymmetry of the compressed air flow exiting the air valve 890 ", but it also allows the compressed air flow to follow the venturi mixing tube 868 inlet to the premixer. It allows for a more even distribution in the housing, which minimizes the pressure drop along the air flow path from the air valve to the venturi inlet, thus maintaining maximum engine power levels while maintaining low emissions levels. It can be higher.

The outlet nozzle assembly can be connected to the mixing tube by any installation method known to those skilled in the art. For example, Figure 10
And the flange section on the nozzle assembly 872 as shown in FIG.
915 and the attachment part 917 may be provided and the nozzle assembly may be connected to a mixing pipe having an engaging flange structure. It is also possible to incorporate the nozzle assembly into the entire structure by means of a mixing tube.

With further reference to FIGS. 8 and 9, the mixing tube is connected to a liner and the flow axis of the mixing tube is oriented generally intersecting the liner axis. However, at least some of the channels of the outlet nozzle are configured to deliver the fuel / air mixture into the combustion zone substantially tangential to the liner axis. Since the combustor inlet opening is not long, this radial orientation of the mixing tube
Accurate sliding contact between the mixing tube and the combustor liner. This results in less leakage and less lateral movement and thermal strain during operation.

Specifically, by orienting the nozzle assembly 872 such that the fuel / air mixture flows in a direction substantially between liner wall 840a and liner wall 840b, a combustion zone is provided.
Produces a controlled vortex and combustion within 854. Mixing tube 8
The 68 is mounted radially on the liner 840 so that the mixing tube flow axis 874 substantially intersects the liner axis 842. Split flow of fuel / air mixture causes liner walls 840a, 84
The placement need not be accurate as long as it is delivered by the nozzle assembly 872 into the combustion chamber with little impact on 0b. Although some impact on the liner wall is expected, it is preferred to minimize the amount of fuel / air mixture impinging on a given surface to reduce the amount of carbon deposited on such surface during the combustion process. Areas of the liner with carbon deposits are thermally insulated, causing thermal fatigue and localized heating problems in the combustion chamber.

8-11, during operation, compressed air coming from the plenum 830 flows along the flow path 882 on the outer surface of the liner 840 to cool the liner 840 (particularly the portion surrounding the combustion zone 854). A portion of the compressed air flowing in the flow path 882 enters the plenum 884 via the orifice 885 and then the fuel / air premixer housing assembly 862 and the plenum 884 (compressed air valve 890 via the controller 894).
(More controlled) between the fuel / air premixer assembly 860 and the fuel / air premixer assembly 860. This part of the compressed air
Almost all are used for combustion except for leaks and driving air blast type fuel nozzles. In the mixing tube 868, the compressed air portion is mixed with fuel coming from the fuel nozzle 864, and in the case where the nozzle 864 is an "air blast type nozzle", with a small amount of additional compressed air portion and then the mixing tube axis 87.
4 to a nozzle assembly 872, where the fuel / air mixture is split into flow paths along channel 901,
It is accelerated out of port 907 and into combustion zone 854 of combustion chamber 852. The orientation and size of the nozzle assembly port 907 can control the flow and direction of the fuel / air mixture into the combustion volume.

After combustion of the fuel / air mixture in the combustion zone 854, the hot exhaust gas enters the dilution zone 856 and the dilution port 858.
The dilution air coming from it lowers the average temperature of the exhaust gas. The exhaust gas then passes through vane 834 to channel 850.
It is exhausted to the turbine 820 and expands to work.

By thoroughly mixing the fuel and air outside the combustion chamber in the fuel / air premixer (including the complete vaporization of the fuel if liquid fuel is used), the features of the present invention can be realized. The combustion system 810 has a combustion system and by controlling the fuel / air ratio in the mixture delivered to the combustion chamber, the NOx, unburned fuel and fuel by-products from the engine module 812 are controlled as described above. The level can be significantly reduced. Furthermore, effectively using almost all of the compressed air stream to burn fuel or dilute the exhaust gas upstream of the turbine not only improves efficiency, but also significantly lowers the peak temperature of the combustor, Extends the life of the combustor liner as compared to the construction of.

The system described separates various geometric flow devices from the hot region of the combustor and
It is expected that pollutant emissions will be reduced at all power levels for gas turbine applications with high inlet temperatures.

FIG. 12 shows another pre-stage structure of the present invention. In particular, the nozzle assembly 972 has a single channel 1001 which, due to its downwardly sloping surface, delivers the flow of the fuel / air mixture substantially tangentially to the combustion chamber. The nozzle assembly 972 further includes a single port 1007 that communicates with the channel 1001 for distributing the fuel / air mixture within the combustion chamber 952. Port 1007 to accelerate the fuel / air mixture delivered to the combustion chamber 952.
Total cross-sectional area of mixing tube 968 (generally indicated by reference numeral 913)
It is preferably about 70 to 90% of the cross-sectional area of

Although the above description relates to a radially mounted mixing tube having a nozzle assembly extending into the combustion chamber, the present invention and its advantages are applicable to other mixing tube positions and configurations. For example, the mixing tube may be connected to the liner such that the flow axis of the mixing tube is oriented slightly tangential to the liner axis. As such, the geometry at the liner inlet remains simplified as compared to, for example, the structure shown in FIG. 1B (where the Venturi axis 74 is substantially tangential to the liner axis 42). The exit nozzle of the mixing tube or other structure can be oriented so that the fuel / air mixture stream enters the combustion zone tangentially and the flow impinges on the liner at a minimum.

Further, the present invention can be utilized with a can-type combustor structure as shown in FIG. In FIG.
Combustor system 1100 comprises a combustion chamber 1112 having a combustion zone 1113 formed by a combustion chamber liner 1114. Spaced around the liner 1114 is a pressure vessel 11 that partially acts as a cooling shroud.
16 The premixer assembly 1126 is arranged to deliver the fuel / air mixture into the combustion zone 1113 of the chamber 1112, the air valve 1128, the Venturi type mixing tube 1130 (some of which are located outside the liner 1114). A nozzle assembly portion 1132. A fuel nozzle assembly 1138 attached to the premixer housing 1139 delivers fuel spray to the inlet region 1131 of the mixing tube, and within the mixing tube 1130 the fuel spray is valve 11
It is mixed by 28 with a controlled amount of compressed air (supplied from compressor 1102). As shown in FIG. 13, the valve 1128 is a cylindrical three-way valve having a rotatable sleeve 1128a, but other valves may be used. The valve 1128 can deliver air to the Venturi mixing tube 1130 or to the second dilution port 1140 in the liner 1114 via the bypass tube 1142 and the manifold 1144 described above.

FIG. 13A is an enlarged view of a part of FIG.
Shown is a pneumatic valve 1128 having a rotatable sleeve 1128a.
The sleeve 1128a is an annular segment that can act as a seal for about 1/3 of the inner circumference of the valve. sleeve
1128a is a position that blocks airflow from the position that completely blocks the inlet 1142a to the bypass pipe 1142 (shown by the solid line in FIG. 13A) to the venturi mixing pipe 1130 through the premixer housing 1139 (shown in dotted line in FIG. 13A). ) Can be rotated about an axis by an actuator (not shown),
Allows bypass flow to a second dilution port (not shown).

In the case of an engine requiring multiple premixers, each can combustor (shown in FIG. 13A) or each pair of combustors, such as the embodiment shown in FIGS. 14A-14D (discussed below). An air valve can be provided and then connected to a common actuator (all valves actuated at the same time as the variable stator blades move on the axial compressor). Therefore, as will be described later, those skilled in the art can easily apply the present invention to such an engine.

Further in FIG. 13A, the first dilution port 11
A part of the compressed air is sucked from the compressor 1102 at a position 60 upstream of the manifold 1128b of the valve 1128. Those skilled in the art will appreciate that the dilution portion depends on the pressure drop in each flow path and the number and size of dilution ports 1160. The portion of the liner 1114 forming the combustion zone 1113 sucks air in except for the mixing tube 1130 and the gap 1130a located at the chamber inlet 1113a to maintain control of the fuel / air ratio and maintain low exhaust gas volume. Intentionally sealed to prevent Gap 1130a between mixing tube 1130 and pressure vessel 1116
Is provided to allow sufficient combustion air to flow during idling. This arrangement simplifies the construction of the air valve, since it is no longer necessary to flow the low flow rate mixture required when idling.

Nozzle assembly 1132 is part of mixing tube 1130 and extends into combustion chamber 1112 at the center of can combustor liner 1114. Further, as shown in FIG. 13B, the nozzle assembly 1132 includes a surface vortex member 1135a forming four channels (directing the fuel / air mixture in chamber 1112 to port 1133, thus optimizing available combustion volume). End plate 1135 having. All four ports 1133 are symmetrically arranged around the mixing tube axis 1130a, but fewer or more ports can be arranged asymmetrically. To increase the velocity of the fuel / air mixture entering the channel 1112 from the port 1133, the total area at the port 1133 of the nozzle assembly 1132 is approximately 70 of the maximum cross sectional area of the mixing tube 1130.
Should be ~ 90%. Even with the above structure, the advantages of the nozzle assembly 872 of the embodiment of FIG. 8 can be obtained.

A three-way valve 1128 has been shown to be very useful in applications where high speed bypass airflow (through the cooling channel formed by liner 1114 and pressure vessel 1116) is required during low power operation. The can combustor system 1100 can also be used with the two-way air valves described elsewhere. The combustor system 1100 also includes an axial engine having an axial compressor section 1102 and an axial turbine section 1104.
13 schematically indicated at 1106). The combustor system 1100 using a can combustion chamber can be used in engine constructions using radial and axial-radial mixed compressors and turbines.

Also, one or more combustor systems may be attached to the axis 1106.
Along the circumference of the turbine, each hot gas collected and distributed in the turbine inlet plenum 1108 can provide low exhaust gas operation of the engine.

14A-14D show the construction of a gas turbine engine having a combustion system in which it is advantageous to utilize the present invention. Specifically, FIG. 14A shows a cross section of a gas turbine engine 1210 having a compressor section 1214 and a turbine section 1216 operatively connected to rotate about an engine axis 1218. The engine 1210 is formed by the liner 1222 and includes a combustion zone 1224 and a dilution zone 1226.
An annular combustion chamber 1220 having Cooling shroud 1228 surrounds liner 1222 and provides a flow path for convective cooling of liner 1222, particularly near combustion zone 1224. As with the other embodiments described above, the combustion zone 1224 includes channels 1262 and 1268 between shroud 1228 and liner 1220.
It is sealed from the cooling air flowing through it (see Figure 14D).
Therefore, the combustion zone 1224 is more than the combustion zone from the premixer assembly 1230.
Intake combustion air only as a substantial portion of the fuel / air mixture delivered to the 1224 (detailed below). Therefore, it can be said that the combustion zone 1224 constitutes a "single-stage" combustion zone.

Further referring to FIG. 14A, the premixer assembly
1230 is a pair of premixers 1232 (only one shown in Figure 14A)
Each premixer 1232 has a Venturi type mixing tube 1234 arranged to suck fuel from the fuel nozzle 1236 and suck air from the premixer housing 1238 via the venturi inlet 1240. Venturi type mixing tube
1234 aligns the nozzle assembly 1244 along the Venturi axis 1242.
Is configured to deliver the fuel / air mixture to the combustion zone 1224 via. The nozzle assembly 1244 consists of an extension member 1244a and an end cap 1244b, which has channels and ports to allow the fuel / air mixture to enter the combustion zone 1244 at an angle to the venturi axis 1242.
It has a surface shape that forms 1246a and 1246b. For example
See 10 and FIG. Port not shown in Figure 14A
1246 also directs the fuel / air mixture stream in the opposite direction with respect to axis 1242. As can be seen in FIG. 14A, the premixer housing 1238 itself, which surrounds the Venturi mixing tube 1234 and mounts the fuel nozzle 1236, is mounted on the separable end 1250a of the engine pressure vessel 1250.

FIG. 14B is a schematic perspective view of the end of engine 1210, which helps to understand the advantageous construction of engine 1210. As shown in Figure 14B, the pair of premixers 1230 has axes 12
Attached to the separable pressure vessel end 1250a at approximately diametrically opposed positions with respect to 18. The premixer assembly 1230 also has a single stage cylindrical air valve 1252 attached to the end 1250a of the pressure vessel. Manifold
The air valve 1252 is driven by an actuator 1253 to control the flow rate of compressed combustion air supplied to both premixers 1232 along an air flow path through 1254 and a pair of distribution conduits 1256. The distribution conduit 1256 can be of various shapes depending on the spatial constraints imposed by the balance of the combustor and engine components. However, the distribution conduits should be structured so that the pressure drop is minimized and the flow restriction characteristics are approximately equal. Distribution conduit 1256 is shown with a bellows-type connector 1258 leading to a compressed air inlet 1260 in each premixer 1232. Also, the air valve 1252 is the axis
The pre-mixer assembly 1230 is tilted with respect to the 1218 and arranged so as to be substantially equidistant from each pre-mixer 1232. Helps ensure equal pressure drop of. Although not shown in Figure 14B, to allow for flow balancing during manufacturing,
The flow resistance of one or both of the distribution conduits 1256 can be purposely slightly higher or lower than the other. Also, to ensure proper flow balance between the premixers,
Certain flow restriction devices can be used in the distribution conduit 1256, but such a construction is not preferred because it totally restricts the compressed air flow path.

As a result of configuring the premixer assembly 1230 to attach the premixer 1232 as well as the air valve 1252 to the end 1250a of the separable pressure vessel, the entire premixer assembly 1230 is removable along with the end 1250a of the pressure vessel. Is. As best shown in FIG. 14A, removal of the turbine exhaust gas pipe 1262 allows the premixer assembly 1230 to be removed along with the pressure vessel end 1250a. This ease of assembly and disassembly
It is of great importance to the construction of the combustion device shown in Figures 14A-14D.

It is important that the individual premixers 1232 be oriented and configured such that the flow axis 1242 of the Venturi mixing tube 1240 lies radially with respect to the axis 1218 and is inclined axially. That is, the extension of the Venturi axis 1242 intersects or passes through the engine / combustion chamber axis 1218 while at the same time making an angle significantly less than 90 ° with respect to the axis 1218, as shown schematically in FIG. 14B.
This orientation provides the advantage of making efficient use of the normally unused annular space (which surrounds the turbine exhaust) and having a smaller overall "envelope" diameter for engine 1210. This is important for applications where it is necessary to minimize the axial profile (minimize the overall engine profile) as in certain aircraft applications. Further combustion area
By making more effective use of the combustion space in 1224, C
The axial length of the combustion chamber 1220 can be reduced while securing sufficient residence time in the combustor to reduce O and NOx to acceptable values. The advantage of shortening the axis of the combustion chamber 1220 is that it reduces the total heat transfer area that must be cooled by the channels 1262 and 1268 (see Figure 14D). By reducing the required cooling air flow,
Compressed air can be used more effectively in recuperative engine applications, especially when the recovered air is hot.

In FIGS. 14A-14C, which are cross-sectional views of air valve 1252 and distribution manifold 1254, the main flow path for combustion air to the premixer assembly is shown. In particular, the air must first be removed from the combustion chamber liner 1222 and
It flows from the radial compressor unit 1214 along a cooling flow path 1262 formed between the compressor and the air conditioner 28. Single-stage combustion zone 1224
Near the end of the nearby combustion chamber 1220, some of the compressed air flows out through the opening 1264 in the cooling shroud 1228 and is collected in the plenum 1266 formed by the cooling shroud 1228 and pressure vessel portion 1250a. . The shape and number of the openings 1264 are not limited as long as the remaining cooling air is guided and maintains an appropriate speed.

From the plenum 1266, compressed air passes through the air valve 1252 and into the distribution manifold 1254, where it splits into approximately two halves into each premixer (not shown in Figure 14C). Remaining compressed air (portion that does not pass through opening 1264)
Enters the dilution port 1269 (FIG. 14A) along the flow path 1268 along the interior of the annular combustion chamber 1220. Since the combustion is substantially completed in the vicinity of the dilution zone 1226 where the dilution air is introduced, the air flowing along the flow path 1268 does not burn, and the high temperature combustion is performed before flowing into the nozzle guide vanes 1215 and the turbine unit 1216. Only by mixing with the product, the air flow and the amount of heat can be efficiently controlled.

As shown in FIG. 14C, the air valve 1252 is a cylindrical valve having a rotatable inner cylinder section 1252a, and a fuel / air controller (not shown) via an actuator 1253 as in the above embodiment. By control
The airflow through the air valve can be opened and closed with continuous opening. Other types of air valves, such as butterfly valves, may be used, but cylindrical valves have been found to be preferred as they exhibit more predictable flow characteristics and are less susceptible to aerodynamic variations at low flow rates. The cylindrical air valve 1252 shown in Figure 14C is a "two-way air valve", but may be modified to include a three-way valve for use with a second set of dilution ports. Such a structure is used for the second dilution port 1272 (Fig. 14A).
14A, 14B showing bypass conduit 1270 connected to
And shown in dotted lines in FIG. 14C and similar to the system shown by 1144 in FIG. The advantage of such a bypass structure is that the applicant's US patent application Ser. No. 08 / 892,397 (July 1997).
Filed March 15, 1997) and US Preliminary Application No. 60 / 038,943 (filed March 7, 1997), both of which are incorporated herein by reference.

FIG. 14D is an enlarged cross-sectional view of the premixer shown in FIG. 14A, showing additional features of the preferred construction in more detail. Specifically, FIG. 14D shows the premixer housing 12
A venturi mixing tube 1234 having a cylindrical flange 1280 forming an annular opening with 38 is shown. The annular opening is shaped and sized to allow a sufficient amount of compressed air to drive the engine 1210 in an idle condition. That is, the air flow through opening 1282 is the same plenum that supplies air to the premixer via air valve 1252.
Taken from 1266 but not directly controlled as it bypasses air valve 1252. This arrangement simplifies the structure of the air valve 1252 as it does not require even the smallest amount of air to pass in order to maintain combustion in the idle state. The openings 1282 can be constructed to provide a predictable and easily controllable air velocity.

As shown in FIG. 14D, the flow leveling grid
1284 is mounted within a premixer housing 1238 and surrounds the Venturi mixing tube 1234 near the inlet 1240. The action of the grid 1284 redistributes the flow entering the premixer housing 1238 via the inlet 1260 and evens out the flow asymmetry due to the structural features of the premixer housing 1238, thus providing a venturi inlet 12
More uniform circumferential flow into 40. The grid 1284 can have equally spaced orifices of the same size, but the locations or sizes of the orifices can be asymmetric to achieve the desired redistribution of flow near the venturi inlet 1240.

As shown in FIG. 14D, increasing the residence time slows the axial flow of combustion products in the combustor 1220 to lower the CO level and strengthens the structure against bending and the like. For the combustor liner 1222
A circumferential recess 1222a is provided in the. Nozzle assembly 1244
Is clearly asymmetrical about the outlet ports 1246a and 1246b formed in cooperation with the nozzle end cap 1244b and the extension 1244a. As mentioned above, the asymmetry of the nozzle outlet port allows good entry of the fuel / air mixture into the combustion zone while preventing excessive direct impact of the fuel / air mixture near the combustor liner. . That is, the outlet ports 1246a and 1246b allow the fuel / air mixture to enter at different angles with respect to the venturi axis 1242 and are related to the nozzle orientation within the combustion chamber. Similar to the embodiments shown in FIGS. 8, 9, 9A and 9B, the total outlet area of the nozzle outlet ports 1246a and 1246b is less than the maximum flow cross-sectional area within the venturi type mixing tube 1234, thus Flashback "and accelerates the flow through the nozzle port to reduce the possibility of combustion in the Venturi mixing tube. In general, the flow cross section is greatest at the end of the bifurcation of the venturi region for a venturi mixing tube.

Although a pair of premixers 1232 are shown in the embodiments of FIGS. 14A-14D, more than two pairs may be used,
Each pair feeds an inclined portion of the combustion chamber and has a single air valve and a respective distribution manifold and distribution conduit located between the associated premixers. Generally, for relatively large engines, multiple premixers are included to achieve a substantially uniform distribution of gas flow rates in all parts of the combustion zone and to minimize variations in heat transfer to the liner. Is highly preferred. Port 12 in the embodiment of FIGS. 14A-14D
The shape, position and number of nozzle ports such as 46a and 1246b also affect the distribution of gas flow rates and must be considered.

It is also possible to use multiple premixers with each associated air valve and actuator, but the actuators are interconnected to achieve uniform control, for example by rotating rings. Yet another embodiment uses a single air valve connected to multiple premixers via a donut-shaped plenum. Such a structure is shown in FIGS. 15A and 15B (individual fuel nozzles 13
Engine 1310 with multiple premixers 1312 having 14
Is a longitudinal sectional view and an end view of FIG.
A single air valve 1316 controls the flow of combustion air to a distribution plenum 1318 in communication with each premixer 1312. Plenum
The flow cross section of 1318 is large enough so that the pressure drop along the flow path from valve 1316 to the individual premixers is substantially the same, ensuring balanced flow. The air valve 1316 is
It can be fitted around the pressure vessel 1320 as appropriate and is preferably of the "cylindrical" type as described in the above examples. Figure 15
As can be seen from A, compressed air passes through the flow path 1322 between the pressure vessel 1320 and the cooling shroud 1324, and through the opening 1334 from the cooling flow path 1326 between the shroud 1324 and the liner 1328. Both flow directly into the air valve 1316 from a compressor (not shown). Circumferential seal 1330 prevents compressed air from flowing directly from channels 1322 and 1326 to plenum 1318. The air valve 1316 is a "three-way valve" that prevents excess compressed air from flowing directly through conduit 1332 to a second dilution port (not shown).

As broadly described and claimed herein, the present invention purports to provide a variable geometry mixing tube outlet for controlling the velocity of the fuel / air mixture entering the combustor. In that respect, it provides an important improvement over the single-stage combustion apparatus and method.

As described above, the conventional single-stage (constant fuel / air ratio type) premixer system has an air valve, a fuel valve, a Venturi type mixing pipe and a Venturi outlet nozzle having a constant area as main components. . Under various loads,
The air valve draws different air flow rates to match different fuel additions. With the constant area Venturi outlet valve used in the above construction, the premix exit velocity can vary from less than 20 m / sec to greater than 60 m / sec in a typical single-shaft turbine engine. At the lower end of the outlet velocity problems can be encountered in attempting to achieve stable combustion, and at the upper limit pressure loss and impingement on the combustor wall can be detrimental. With the variable geometry Venturi outlet of the present invention, for example, at a constant and stable outlet velocity of 30 m / sec (independent of power or within a range above and below a given minimum and maximum outlet velocity, respectively), The premixer can be activated. As a result, the following advantages are obtained. 1. Improve predictable combustion performance over the entire load range. 2. Avoid flashbacks at low loads and avoid collisions at high loads. 3. Reduce pressure loss at high loads that can cause "starvation" of air in the Venturi tube. 4. Better utilization of combustors at high fuel / air velocities.

FIG. 16 illustrates a gas turbine engine having a combustion system according to a first embodiment of the present invention, which may result from uncontrolled mixing tube exit velocity flashback, flame instability and / or flame instability. 1 illustrates a gas turbine engine using a premixer assembly having a variable outlet geometry that minimizes or eliminates the side effect of collision. The method and apparatus of the present invention are advantageously and preferably used with the above-described structure resulting in a mixture having a controlled fuel / air ratio for single stage combustion for gas turbine engines and gas generators. However, the present invention is not limited to such applications.

Specifically, FIG. 16 shows the engine axis 1418.
FIG. 14A illustrates a cross section of a gas turbine engine 1410 having a compressor section (not shown) and a turbine section 1416 operatively connected for rotation about a rotor. Engine 1410 has an annular combustor chamber 1420 formed by a liner 1422 having a combustion zone 1424 and a dilution zone (not shown). The cooling shroud 1428 surrounds the liner 1422,
Particularly, a flow path for convectively cooling the liner 1422 is formed near the combustion zone 1424. Combustion zone 14
24 is the flow path 1462 between shroud 1428 and liner 1420.
And are preferably sealed from cooling air flowing through 1468 (see, eg, Figure 14D). In this way the combustion area 1424
Constitutes a "single-stage" combustion zone because it receives combustion air only as a substantial portion of the fuel / air mixture that is delivered to combustion zone 1424 via premixer assembly 1430 (described in more detail below). To do.

According to the broadly described invention, a premixer device for mixing fuel and compressed air from each source to obtain a fuel / air mixture is provided in (a) a compressed air source and a fuel source. An operably connected premixer housing, and (b) having a fuel and compressed air inlet, an axis, and an outlet (having a catchment area) for delivering a fuel / air mixture, disposed within the housing. Mixing tube, (c)
A mixing valve for varying the velocity of the fuel / air mixture passing through the outlet.

Subsequently, as specifically shown in FIG. 16, the premixer assembly 1430 includes a premixer 1432 having a Venturi type mixing tube 1434, and the Venturi type mixing tube is provided.
1434 is arranged to inhale fuel from a supply source (not shown) via fuel valve 1435 and fuel nozzle 1436 and inhale air from premixer housing 1438 via venturi inlet 1440. Venturi mixing tube 1434 passes through mixing valve assembly 1444 along venturi tube axis 1442 to combustion zone 1424.
Has a structure for delivering a fuel / air mixture to the.

Further, in FIG. 16, the mixing valve 1444 is formed by the valve member 1452 and the outlet portion 1454 of the mixing pipe 1434, as will be described later. The valve member 1444 has an elongated stem 1446 disposed substantially along the mixing tube axis 1442 and a conical plate member 1448 disposed near the mixing tube outlet 1454. The valve actuator 1456 engages the stem end 1450 via drive means 1458 configured to selectively move the stem portion 1446 and plate member 1452 along the mixing tube axis 1442. Valve actuator 1456, as will be apparent to those skilled in the art.
Has cam driving means, screw driving means, rack and pinion driving means, or hydraulic / pneumatic driving means, and is located at a position separated from the combustion zone 1424. As shown, drive means
The 1458 has a cam 1449 that interacts with a spring follower 1447 coupled to the stem 1446 and is movable to infinitely variable positions and can provide speed control. The relatively simple two-position control of valve movement using a mechanical stop (not shown) can also be used for speed control at some cost. The stem 1446 extends through an opening 1460 in the premixer housing 1438. Plate member 1448
As the valve stem 1446 is actuated axially in one or the other direction due to the effect of, the effective outlet flow area at the mixing tube outlet 1454 increases or decreases.

The stem 1446 extends through the opening 1462 of the mixing tube 1434, and the portion 1434a of the mixing tube 1434 near the inlet is described.
Is preferably curved away from the axis 1442. The valve actuator 1456 can engage the stem 1446 outside the housing 1438 and the mixing tube 1434.

Further, as shown in FIG. 16, the valve member 1452 is
It preferably has an associated cooling channel 1466 (in communication with conduit 1468 of stem 1446) formed in plate member 1448. The conduit 1468 communicates with an inlet 1470 that is operatively connected to the conduit 1468 that draws compressed air from the housing 1438. The plate member 1448 is preferably formed in the shape of a hollow inverted cone having a base edge portion 1472 and a number of channel outlets 1474 distributed around the base edge portion 1472. The cooling channel 1466 has a function of cooling the plate member 1448. Compressed air entering the combustion chamber 1424 directly through the cooling channel 1466 is small, not significantly affecting the average or local fuel / air ratio. The hollow conical shape creates a space for recirculation of the fuel / air mixture downstream of the premixer outlet, thus improving flame holding and combustion stability (see, eg, discussion with respect to FIG. 11).

In operation, valve member 1452 is moved by stem 1446 along axis 1442. The stem 1446 is fixed to a spring follower 1447 that abuts a cam 1449 rotated by an actuator 1456 in the direction of the controller 1457, for example. As shown in FIG. 16, the controller 1457 (which may be a microprocessor) controls the valve stem 14 based on engine power (actual or demand) or related variables.
It controls the position of 46 and thus the basin of the mixing tube outlet. In general, the high flow rates at the mixing tube outlets associated with high power conditions result in velocities higher than required for a given outlet area, thus reducing the outlet velocities to reduce flame instability and / or collisions. The need to increase. This is accomplished by moving the valve stem 1446 to the left, which is shown schematically in FIG. On the other hand, in the case of idling flow (minimum flow rate of the mixture), it is necessary to reduce the water basin by moving the stem 1446 to the right, so that the exit speed should be set to a minimum level to guard against flashback. Make it higher

Further, according to the present invention, it is preferable to provide a sensor for detecting the pressure upstream of the outlet of the mixing tube. A mixing valve actuator operatively connected to the mixing valve at the outlet of the mixing tube, and a pressure sensor and a controller operatively connected to the mixing valve actuator are arranged to change the basin of the mixing tube outlet in response to the detected pressure. You can The controller controls the mixing tube outlet basin such that the mixing tube outlet basin is greater than a predetermined minimum value and less than a predetermined maximum value.

Further, as shown in FIG. 16, the sensor 1480 has an element 1480a for detecting the pressure upstream of the mixing tube outlet basin between the plate 1464 and the mixing tube outlet 1454. Sensor 1480
Are operatively connected to controller 1457, which is operatively coupled to an actuator 1456 that engages valve stem 1446. Thus, in response to either the sensed pressure condition alone, or both the pressure condition and the output level, which may vary as described above, the controller 1457 controls the mixing valve 1452 to obtain the desired fuel / air mixture exit velocity. The basin at the outlet of the mixing tube can be changed as described above.
Generally, the exit speed may be controlled to a value above a predetermined minimum value that avoids flashback and below a predetermined maximum value that causes flame instability and / or collision problems. This control can be done by a two position control scheme for the plate member 1448. However, with the infinitely variable position control that can be achieved using the cam drive means shown in FIG. 16, using a suitably programmed microprocessor for controller 1457, a single target value (eg, 30 m / Sec) can control the speed.

FIG. 16 further illustrates a controller 1457 used to control the fuel valve 1435 (and hence engine power),
Premixer housing 1438 to dilution port (not shown)
The activation / valve 1486 controlling the compressed air bypass 1488 up to the second set of is shown. The purpose of the bypass 1488 is to prevent excessive pressure drop in the coolant passage 1468 leading to the first dilution port (not shown) for the reasons discussed above in connection with the structure shown in FIG.

FIG. 17A detailing a modification of the embodiment of FIG.
As shown in, the plate member 1448 'can be formed into a hollow conical shape having a base edge portion 1472'. Base edge part 1472 '
Is a fence 14 located to separate the boundary layer formed on the plate member 1448 'by the flow of the fuel / air mixture.
Has a 76 '. The premixer outlet 1454 'also has sharp edges to enhance agitation mixing.

A venturi tube 1434 "should be separated from the liner 1422" and cooling shroud 1428 "by a sleeve member 1478", as shown in FIG. 17B which also details another variation of the embodiment of FIG. You can Sleeve member
The 1478 "constitutes a coolant cooling channel 1478a" to prevent excessive temperature at the venturi outlet 1454 ". The compressed airflow passes through the venturi mixing tube 1434" to the combustion zone 1424 "via the coolant cooling channel 1478a". Since it flows in directly, the fuel / air ratio does not have to be controlled to the extent possible (depending on the thermal barrier coating to prevent excessive temperature at the mixing tube outlet) with the variations of FIGS. 16 and 17A. However, the modification (not currently preferred) shown in FIG. 17B is also part of the invention in its broadest sense and is expected to minimize collision flashback and fuel retention as described above.

18A to 18C show another modification of the embodiment shown in FIG. 16, respectively. As shown in Figure 18A, mix valve 15
52 is provided at the outlet 1554 of the mixing tube 1534. Mixing valve 15
52 has a valve plate 1564 of a preferably hollow conical valve member 1552 cooperating with a mixing tube outlet 1554. An outlet basin is formed between the valve plate 1564 and the mixing tube outlet 1554 to allow the fuel / air mixture to enter the combustion zone 1524. The plate member 1564 is a stem
It is connected to 1546 and has a cooling channel 1566. Valve stem 15
46 is an actuator 1556 under the control of controller 1557.
Moves along axis 1542. As described with respect to FIG. 16, the outlet basin varies with the axial position of the plate member 1564 relative to the mixing tube outlet 1554.

Importantly compared to the embodiment shown in FIG. 16, the embodiment shown in FIGS. 18A-18C works in conjunction with each fuel valve to determine the fuel / air ratio of the mixture in the mixing tube. Having an air valve / actuator assembly. Referring first to FIG. 18A showing a single premixer engine structure, the air valve / actuator assembly 1590 is connected to the controller 1557.
Control the compressed air flow entering the premixer 1530 directly. When controlling both the fuel supplied from the nozzle 1536 via the fuel valve 1535 and the compressed air supplied via the air valve assembly 1590, almost all the combustion air enters the premixer as shown in FIG. A mixture having a different fuel / air ratio enters combustion zone 1524. The advantages of the present invention of controlling the area of the mixing tube outlet are not limited to devices that control the fuel / air ratio of the mixture, but minimize flashback, flame instability and / or collision phenomena, and
Combusting a mixture having a controlled fuel / air ratio as described above provides significant advantages.

However, the "pneumatic valveless" embodiment shown in FIG. 16 has a fuel / air ratio in applications where the compressed air flow is a function of power level, as described with respect to the structure shown in FIGS. 5A and 5B. Can be used to control

Furthermore, FIG. 13A, FIG. 14C, FIG. 15A and FIG. 15B
Similar to that shown in Figure 3, the air valve assembly 1590 is a three-way valve that regulates the air flow into the premixer housing 1538, and thus the venturi inlet 1540, and the second dilution port (not shown) via bypass 1588. Having 1592. However, if the bypass feature described above is not used, the premixer device of the present invention can be configured with a two-way air valve.

Further, the premixer device may have a multistage premixer, like the single stage premixer shown in FIG. 18A. FIG. 18B is an axial end view of an engine structure having four premixers, one air valve and one fuel valve, which engine configuration results in U.S. patent application Ser. No. 60 / 081,465 (herein incorporated by reference). Quoting and forming part of the description) save space. Specifically, the engine shown schematically in FIG. 18B controls the fuel flowing into the premixer 1532 'through the fuel valve 1535', and also controls the fuel flow in the premixer assembly 1530 '.
An air valve / actuator assembly 1590 'is used to control the combustion air entering each of the two premixers 1532'. The axis of the mixing tube of the premixer 1532 'is typically the axis 1518' (similar to the configuration shown in Figure 14B).
Less than 90 ° to 8 ').
FIG. 18C is a schematic cross-sectional view taken along the line AA of FIG. 18B.
Premixer assembly 15 located circumferentially spaced from air valve / actuator assembly 1590 'about axis 1518'
A 30 'premixer 1532' is shown. In Figure 18C, Figure 15
In the same way as described for the structure shown in A, the compressed air coming from the compressor is forced by the annular seal 1594 'into the air valve 15
Delivered to 92 '. Air exiting valve 1592 'is also distributed to individual premixers 1532' via manifold 1598 '. A manifold 1598 'is located within an annular space surrounding a conical exhaust 1600', as described in U.S. Patent Application No. 60 / 081,465.

The premixer system of the present invention also includes a separate air valve and fuel valve for each premixer instead of the single air valve 1592 'and fuel valve 1535' used in the embodiment shown in Figures 18B and 18C. You may have. See Figure 18A and Figure
Instead of the individual actuators 1556, 1556 'shown in 18C, a system for actuating interconnected mixing valves may be used. Also shown in dotted lines in Figures 18A and 18C are shown in Figure 16 at 1480 and 1480a for input into the controllers 1557 and 1557 'used to control the position of each mixing valve via actuators 1556 and 1556'. The same pressure sensor as the above may be used.

As can be seen further from FIG. 18C, the stem 15
Mixer valve 1552 'with 46' and plate member 1564 'is a fixed member 1596' mounted on premixer housing 1538 '.
It is slidably attached to. As will be apparent to those of ordinary skill in the art, the securing member 1596 'advantageously provides an elongated bearing support for the valve stem 1546'.

FIGS. 19A-19C show an apparatus according to a second embodiment of the invention, a combustor system, and a variable mixing tube outlet geometry for controlling the velocity of the fuel / air mixture entering the combustor from the premixer. The gas turbine engine used is shown. Specifically, FIG. 19A shows a gas turbine engine 1910 having a compressor section 1912, an annular combustor 1920 and a radial turbine 1916 arranged similarly to the engine structure shown in FIG. The engine 1910 has a single premixer 1932 which is supplied with a controlled flow of compressed compressed air from a single air valve 1990 via a pair of manifolds 1925, 1927 (only 1925 visible in Figure 19A). As shown in FIG. 19A, the air valve 1990 is intentionally placed at an angular position that is diametrically opposed to the premixer 1932 for reasons to be described later. Although a single premixer is shown in FIGS. 19-19C, a multistage premixer with single or multiple air valves may be used with the present invention. The premixer may also be tilted with respect to the engine axis 1918, as shown in FIGS. 14-15 except that a pre-stage premixer combustor system is used.

As best shown in FIGS. 19B and 19C, the premixer 1932 has a venturi mixing tube 1946 having an inlet section 1946a and an outlet section 1946b connected by a sliding joint 1947. Joint 1947 is Venturi 1946a (fixed to premixer)
And a portion 1946b which is movable along the axis 1974 of the mixing tube by a pair of rack and pinion driving means 1951, 1953, and has a relatively slidable structure. Drive means 19
51,1953 are installed in the premixer 1938,
It can be driven synchronously by an electrical, hydraulic or pneumatic actuator (not shown) mounted outside the premixer housing 1938 under the control of a controller 1994, shown schematically in FIG. 19B. For explanation purposes only,
19B and 19C, the part of the venturi portion 1946b on the left side of the venturi tube axis 1974 is shown in a position sufficiently (upwardly) retracted with respect to the insertion depth into the combustion zone 1924, and The portion of portion 1946b to the right of axis 1974 is shown in the fully (downward) expanded position.

As best shown in FIG. 19C, the moveable venturi portion 1946b has a nozzle assembly 1972. Nozzle assembly 1972 is a sleeve extension connected to a hollow conical end cap 1903 and a venturi section 1946b.
1907 and the wall or rib 1905 that forms the nozzle outlet port 1909 with the sleeve 1907 and the end cap 1903.
Have. The outlet port 1909 has a separate, generally cylindrical, annular outlet basin. Nozzle assembly 1972 is similar to the nozzle assembly structure for use with the pre-stage system, especially the asymmetric nozzle assembly structure (shown in detail in FIGS. 10 and 11) for use with annular combustors. ing. The nozzle assembly 1972 along with the venturi section 1946b
Slidingly disposed within the coaxial skirt 1949.
The skirt portion 1949 is connected to the engine pressure vessel 1914 and, like the venturi portion 1946a, the movable venturi portion 1914.
It is "fixed" to 46b and attached to the nozzle assembly 1972. FIG. 19C also shows cooling holes 1967 formed in the skirt 1949. Cooling hole 1967 is the skirt
A small amount of cooling air is made to flow axially between 1949 and the movable venturi portion 1946b, so that the combustion area 1924 of the skirt portion is
Reduce the operating temperature of the portion 1949a extending to.

It is important to note that the skirt end 1949a and the nozzle assembly outlet port can be seen in FIG. 19C.
The extent of overlap with 1909 limits the basin available to the fuel / air mixture. In this sense, the movable nozzle assembly 1972 and the fixed skirt member 1949 cooperate to produce the outlet port 1909 depending on the moving direction of the venturi portion 1946b.
Acts as a valve to increase or decrease the effective basin of the fuel / air mixture passing through. That is, a venturi section 1946b and nozzle assembly 1972 are shown in FIG. 19C for a given flow rate of the fuel / air mixture through the premixer 1932, as described above with respect to the embodiment of the invention shown in FIGS. 16-18. Decreasing the available outlet basin by pulling upwards will increase the velocity of the fuel / air mixture, while moving the venturi section 1946b of the structure shown in Figure 19C downwards will increase the available basin and thus the mixture outlet. Slow down.

The advantages provided by nozzle assembly 1972 are:
Distributing the fuel / air mixture into the annular combustor without excessive wall impingement, as described with respect to the pre-stage construction shown in FIGS. 8-11. Similar to the embodiment of FIG. 8, the nozzle assembly 1972 also has a structure in which the basin area of the outlet port is reduced with respect to the basin of the mixing tube, thereby accelerating the flow through the port 1909 and providing a margin for flashback. Can be large. Although not shown in the drawing, the structure of the mixing tube and the skirt part, for example, the structure of the unitary movable mixing tube or the fixed unitary Venturi mixing tube (and the nozzle assembly) together with the part forming the axially movable skirt section is changed. Examples are also clearly within the scope of the invention. As will be readily appreciated by those skilled in the art, it is the relative movement between the components that provides the desired mixing valve effect. Therefore, in this sense, the present invention is limited only to the claims and their equivalents, and not to the specific embodiments described.

Referring also to FIG. 19B, in operation, the fuel / air premixer 1932 has a cylindrical air valve 1990 and a manifold 19
Gas turbine engine compressor 1912 through 25,1927
Inhale compressed air (not shown in Figure 19B).
The manifolds 1925 and 1927 can be separate conduits, but Figure 19B
It may be formed by a member cooperating with the outer surface of the pressure vessel 1914 as shown in FIG. As shown in Figure 19B, compressor 19
Air coming from 12 is pressure vessel 1914 and cooling shroud 19
Between 28 the flow is almost axial. After that, a part of the compressed air flows through the collision cooling holes 1981 and 1983, but the rest flows circumferentially and flows into the air valve 1990. Although shown as a "two-way" air valve in Figure 19B, the air valve 1990
A portion of the compressed air that is not directly required for combustion or impingement cooling is directed into the second set of dilution ports (not shown), thus between the combustor liner 1922 and the cooling liner 1928 (ie axially). A three-way valve having a structure that bypasses the regular flow path for the cooling air and flows into the first dilution port (not shown) may be used. The advantages of such an arrangement and its description are fully described in the description of a pre-stage system such as the system shown in FIGS. 13A-13C.

The compressed air sent from the air valve 1990 to the premixer housing 1938 through the manifolds 1925 and 1927 is the venturi inlet part which is the fixed part of the venturi mixing tube.
Enter Venturi tube 1946 via 1946a. This air mixes with fuel coming from fuel valve 1985 as it flows along premixer axis 1974 until it reaches end cap 1903 of nozzle assembly 1972. In the nozzle assembly 1972, the mixture is deflected away from the premixer axis 1974 and distributed in opposite tangential directions indicated by arrows F ₁ and F ₂ in FIG. 19C and in the direction of the engine axis 1918 (not shown). . In FIG. 19C, the flow arrow F ₁ is a flow arrow F _{1.
It is shown} to be larger and longer than ₂ so that when the nozzle outlet port is fully extended and opened (to the right of the premixer axis 1974 in Figure 19C), the nozzle outlet port opening is partially covered by the skirt 1949. When restricted (Fig.
The left side of the premixer axis 1974 at 19C) indicates that the velocity through the nozzle outlet port 1909 is higher.

The movement of the Venturi mixing tube 1946 can be varied to obtain an intermediate open area, but the fuel / air ratio is controlled by the air valve 1990 as shown in FIG. Has retreated or extended)
Is enough. However, the present invention is not limited to the movable venturi section 1946.
It also covers a configuration in which the position of b is controlled to an intermediate position by, for example, controller 1994.

20B and 20A are schematic views showing modifications of the variable shape of the premixer shown in FIGS. 19A to 19C suitable for a can-type combustor. FIG. 13 shows an application such as a can combustor having a premixer outlet system having a fixed front stage geometry. However, the specific use shown in Figure 13 is
It does not limit the application of the embodiments shown in FIGS. 20A and 20B, let alone the scope of the invention.

Specifically, FIG. 20A shows a nozzle assembly 2072.
Shows the lower portion 2046b of the Venturi type mixing tube connected by the. Nozzle assembly 2072 is a conical end cap with an open end
2035, a sleeve extension 2037, and a wedge-shaped rib 2039 having an open end (connecting the end cap 2035 and the sleeve 2037). Wedge rib 2039 and sleeve
Together with 2037, the conical surface of the end cap 2035 forms a plurality of nozzle outlet ports 2033 for admitting the fuel / air mixture into the can combustor. Nozzle port 2033 generally forms a split cylindrical annular outlet basin for nozzle assembly 2072. Open ends of the end cap 2035 and wedge ribs 2039 recirculate the fuel / air mixture (indicated by the curved arrows in FIGS. 20A and 20B) and retain the flame downstream of the outlet port 2033. Therefore, combustion stability is improved.

The nozzle assembly 2072 has the important difference that the nozzle assembly 2072 can move up and down along the mixing tube / premixer axis 2074 with the mixing tube section 2046b, but with the asymmetric structure of the structure shown in FIG. It is similar to the nozzle assembly 1132. As in the embodiment shown in FIGS. 19A-19C, this movement is accomplished by using rack / pinion drive means to move member 2046b relative to a fixed mixing tube section (not shown overall). be able to. Alternatively, an integral mixing tube suitably mounted for sliding within a premixer housing (not shown) carrying the nozzle assembly 2072 may be used.

Importantly, as best shown in FIG. 20B, the lower portion 2049a of the coaxially located stationary skirt 2049 is a valve that forms an effective nozzle flow area through the outlet port 2033. In cooperation with the movable nozzle assembly 2072,
Therefore, it is configured to control the speed of the mixture outlet. The position shown in FIG. 20B is a fully open position and represents the case where the nozzle assembly 2072 has penetrated deepest into the combustor. Those skilled in the art will appreciate that during periods of low power or idling, for example, along the axis 2074 the portion 2046b of the mixing tube and the nozzle assembly 2072 (above) retract,
Axial end 2049a blocks a portion of outlet port 2033, reducing the effective basin and increasing velocity for a given mixture flow rate.

Referring again to FIGS. 19A-19C, additional benefits are achieved by the particular air valve and premixer orientation shown. In the embodiment shown in FIGS.19A-19C, the upper half 1924a of the combustion zone 1924 in the annular combustor 1920, due to its proximity to the premixer nozzle assembly and control of the mixture exit velocity,
It constitutes the majority of the reaction zone where the combustion of fuel takes place, the lower half 19
24b acts like a transfer duct. The cooling scheme of combustor 1920 is designed to comply with this requirement. At full speed, more than 30% of the air volume in the engine is used to cool the upper half of the combustor, and only about 20% is required to cool the lower half. The flow rate of the premixer accounts for about 45% of the air volume and about 5% is needed to cool the hot section under these conditions. Taking air out of the lower half 1924b of the combustor to supply air to the premixer provides a better split for the following reasons.

First, it must divert less air than if the valve were at the top. The compressor delivers air evenly to the pressure vessel 1914 that surrounds the cooling liner 1928, so about 15% (20% + 45% -50%) of the air burns when the premixer is on top and the air valve is on the bottom. Flow from the upper half to the lower half of the engine around the vessel. On the other hand, if the upper part is an air valve and the upper part is a premixer arrangement, approximately 25% (30% + 45% -50%) of the air should move from the lower half to the upper half of the engine. By arranging the air valve in the lower part in this way, the average velocity (and thus the pressure loss) is reduced, so that the water basin is used more efficiently and the pressure drop is reduced.

The second reason for arranging the valve at the bottom in the embodiment shown in FIGS. 19A to 19C is that the air flowing into the air valve is ρ +
1/2 ρ v ² = subject to a static pressure drop according to the equation represented by constant. As the static pressure between the pressure vessel and the cooling liner decreases, the pressure differential across the cooling liner decreases, resulting in a decrease in the flow rate of cooling air through the constant size holes. Closing the valve maximizes the amount and velocity of air flowing in the direction of the valve resulting in the lowest static pressure and lowest impingement cooling flow. However, the impingement cooling flow is reduced when less cooling is required when the reaction zone is at the top. Therefore, in the configuration shown in FIGS. 19A-19C, it is advantageous to remove the air in the premixer from a region where the required level of cooling is low, that is, the bottom of the engine.

In summary, if (1) the amount of air that must be exhausted in the engine is small, and (2) the required level of cooling is the lowest, the pressure that is separated from the premixer outlet is the reason why the maximum static pressure drop occurs. It is advantageous to take the air for the premixer from the area of the container.

In summary, in a premixer with a uniform shaped outlet, the outlet velocity of the premix changes with the position of the air valve. A configuration similar to that shown in Figures 19B and 19C but without a variable geometry outlet (pneumatic valve remains almost closed during idle or low power operation).
In the above, when only a small amount of air passes through the Venturi mixing tube at a velocity and range of about 20 m / sec, the above flame velocity (approximately 10 m
(Less than / sec), you can get a sufficient margin in the faster area.
You can avoid flashbacks. In such a structure, the outlet speed exceeds 70 m / sec at full speed, and unstable combustion may occur. Also at high speed,
There is not enough pressure drop to pass air through the venturi to reduce rated power, or enough cooling air through the cooling shroud to cool the liner and finally outflow from the dilution port. May. In order to reduce the pressure drop and avoid flashback under partial power, it is advantageous to use a premixer structure with a variable outlet geometry as shown in Figures 16-20. If the flow of the compressor changes, for example in a twin-screw engine or any multi-spool engine, the flow rate at idling will be very small at low power, to avoid flashback and thus to avoid combustion inside the premixer. The use of a variable exit premixer becomes more advantageous. Another important advantage of reducing pressure drop in the system is that the constant exit geometry system reduces the exit velocity at full power. This substantially reduces impact and heat load on the combustor liner. A shorter distance from the premixer outlet to obtain the lower flame velocity needed for more stable combustion allows better utilization of the combustor volume.

Various modifications can be made by those skilled in the art based on the combustor system, the fuel / air premixer apparatus and the operating method thereof according to the present invention without departing from the scope of the present invention. Specifically, although the method of practicing the present invention has been described with respect to a radial gas turbine engine, the present invention is not limited to this particular type of gas turbine engine and is intended to be an axial gas turbine engine and an axial / radial mixed engine. Type gas turbine engine. Similarly, a mixing valve actuator, such as actuator 1556 shown in FIG.
Controlled by an actuator (not shown) for the drive means 1951, 1953 under the control of 1994 (currently preferred microprocessor for accuracy) is now preferred for accuracy but simpler An inexpensive structure may be used.

For example, the moveable mixing valve components may be mechanically or hydraulically / pneumatically actuated by the air pressure in the Venturi tube upper box which varies as the setting of the main air valve is changed. Further, the components may be mechanically or hydraulically driven according to the movement of the actuator that operates in response to the movement of the actuator that operates the main air valve. In both cases, the annular air gap is maximum at high load but minimal at idle, thus maintaining a constant speed from idle to full power for continuous position control.
As described above, even if two settings of high-constant are set as an inexpensive aspect, the pre-stage structure is more improved than the fixed shape. All the above explanations regarding cooling and flame holding also apply to this aspect.

21A-21D show yet another embodiment of the device of the present invention. Specifically, in the novel embodiment having a simple structure shown in FIGS. 21A to 21D, the outlet basin of the premixer is changed (applicable to all embodiments), and particularly in FIG.
As shown in FIGS. 19A-19C, the exit direction of the fuel / air mixture is controlled in order to avoid or minimize impingement of the exiting fuel / air mixture on the surface of a nearby combustor liner. The mixing valve used in the embodiment shown in FIGS.21A-21D has an adjustable nozzle structure and
With a fixed skirt forming an outlet port for the fuel / air mixture in a combustor such as an annular combustor, the nozzle structure is hollow conical and centrally mounted axial drive substantially similar to the valve plate shown in FIG. Type movable valve plate.

FIG. 21A shows the outlet port of the Venturi type mixing tube section 2134 of the fuel / air premixer 2132. Mixing tubes of shapes other than Venturi may be used, but Venturi is currently preferred. As shown in FIG. 21A, the mixing valve 2144 has an inner valve member having a plate 2148 and a stem (shaft) 2146, and an outer valve member (skirt) 2149 coaxial with the inner valve member. Plate 21 as described above
Reference numeral 48 is a hollow body having a substantially conical shape in order to enhance the flame holding property.
The plate 2148 is connected to the shaft 2146 by tie bolts 2156, and the shaft bearing 2146 is slidable along the venturi axis 2142 so that the shaft 2146 is slidable.
And at the exit of the Venturi 2134 via the stanchions 2160. In the present invention, three columns 2160 are provided, two of which are shown in FIG. 21A. However,
The number of columns may be more or less.

The shaft 2146 can be driven by a mechanical, hydraulic or pneumatic actuator by a mechanism including a cam and a spring shown in FIG. 16, for example. The drive mechanism shown in FIGS. 19B and 19C can be used for the structure shown in FIG. 21A. In such a construction, remove the bearing 2158 and attach the spherical end 2146a to the tip as shown in Figure 21A.
Plate 2148 with shaft 2146 having (dotted line)
Can be fixed to the column 2160. 19B and 19C
Similar to the structure shown in FIG. 5, an outlet part of the venturi 2134 on which the column 2160 is installed may be movable with respect to a venturi inlet part (not shown) by using an actuator that performs a movement controlled by a gear and a rack. In this case, the skirt member 2146 is fixed to the premixer member or combustor member, such as the premixer housing (not shown), combustor liner or surrounding cooling shroud 2128, but not to the venturi 2134, but at least to be movable. You may connect. Shims 2150 (shown in phantom in Figure 21A) can be used to adjust the initial position of the valve plate in the assembly.

In the embodiment shown in FIGS. 21A-21D, the normal skirt member 2149 is cylindrical and may be in the opposite direction (eg
As in the structure shown in FIG. 19B, it has a notch 2149a forming a port 2109 that guides at least most of the mixed flow in the tangential direction of the annular combustor. Similar to the mixing valve in the embodiment of FIGS. 19A-19C, if the mixing valve 2144 is, for example, asymmetrical, then the mixed flow can be guided vertically along the axis 2118 of the combustion chamber, effectively utilizing the volume of the combustion zone 2124. be able to. This is the cutout 2149a in the modification shown in FIGS. 21A-21D.
Can be easily achieved by adding suitable ports or notches to the opposing port 2109 consisting of 9 at an angle.

In the embodiment shown in FIGS. 21A-21D,
16, the skirt 2149 is fixed and the shaft 2146 holds the plate 21 in place so that the outlet basin meets the requirements of a suitable control system (not shown) as shown in FIGS. 18A and 19B.
Driving 48. Although complicated and costly, the plate 2148 can be fixed to make the skirt 2149 movable, or both can be made movable, according to another aspect of the invention as described above. As mentioned above, the control system can be continuous or stepwise (eg 2
It can also be activated in stages.

In the premixer, the mixing valve 2144 is hermetically attached to the opening of the liner 2122 from which the combustion zone
It projects into 2124. Although a labyrinth seal is shown as the seal of the opening, a piston ring, a brush or other seal may be used. Tested for excessive spillage through unsealed openings, resulting in air curtains around the mixing valve and unstable combustion, especially under operating conditions such as idling or low power operation. Revealed by.

FIG. 21B shows two components of the mixing valve 2144, a plate 2148 and a skirt 2149. Under unfavorable operating conditions, such as using poor liquid fuel, "flashback" can occur toward the exit portion of Venturi 2134. Skirt 2149 and / or plate
If 2148 is made of a metallic material, then skirt 2149 and / or plate 21 may be similar to plate 1448 shown schematically in FIG.
48 may be provided with suitable cooling channels. By providing cooling channels, the skirt 2149 and / or the plate 21 can be protected from thermal damage due to oxidation or meltdown of parts of the member.
48 can be protected. Incidentally, with reference to the disclosure content of the applicant's US application (application number 09 / 721,964, filing date November 27, 2000), relevant matters are described in the present specification as appropriate. Instead of or in combination with cooling channels, a thermal barrier coating (TBC) known to those of ordinary skill in the art as a gas turbine engine component may be formed on the skirt 2149 and / or the plate 2148.

Plate 2148 and / or skirt 2149 are preferably made of a ceramic material. It is preferred to disperse the ceramic fibers in the ceramic material to ensure that cracking due to prolonged engine operation is prevented. The ceramic mixing valve plate 2148 and the skirt 2149 can be easily manufactured by sintering after molding. Shaft 21
The lower portion 2146b of 46 can also be made of ceramic. Although the ceramic shrinks during sintering, the manufacturer of the ceramic article can size the compact so that it will be approximately the final sintered compact shape without undue experimentation. Appropriate finishing may be done to obtain the desired final shape and dimensions.

Due to the difference in expansion coefficient between ceramic and metal,
The ceramic and metal parts can be flexibly clamped by a suitable attachment mechanism. Belleville washers or “wiggle strides” are used to reduce stress on ceramic parts and reduce the risk of cracking by increasing the adaptability of the joint to thermal expansion.
p) "can be used. For example, a Belleville washer (not shown) can be used for shaft / plate joint 2152 in Figure 21A, and lower portion of shaft 2146.
It can be used in place of shim 2150 if 46b is made of ceramic material.

Since the strength of many metals decreases at a temperature about 300 ° C. lower than that of ceramics, flashback can be made less likely to occur by using ceramics. Even if a ceramic material is used for the plate 2148 and skirt 2149, appropriate cooling channels may be placed within the stanchions 2160 (only one of the struts in Figure 21A shows the cooling channels in dotted lines) and tie bolts 2156 (channels in Figure 21A) as needed. The outlet may be located in dotted lines) and / or within the shaft 2146 (cooling channels not shown).

21C and 21D show details of the embodiment shown in FIGS. 21A and 21B. In this embodiment, there is a bayonet pin type clamping mechanism between the ceramic skirt 2149 'and the outlet portion of the metal venturi 2134'. An axial slot at the exit portion of the venturi 2134 'that receives the stamped finger 2168' on the skirt member end 2149b '.
2164 'and an annular groove 2166' are provided. The metal swing band 2170 ′ can bridge the difference in expansion coefficient between the metal component and the ceramic component. Further, by inserting the skirt 2149 'against the swing band 2170' and aligning the finger 2168 'and the recess 2172', the axial holding force for fixing the finger 2168 'in the recess 2172' in the annular groove 2166 '. Can be given. This embodiment has three sets of slots 2164 ', fingers 2168' and recesses.
2172 ′, but the number of sets may be larger or smaller. Further add a circular swing band 2174 'to the skirt 214
A radial centripetal force may be applied to 9 '. The clamp mechanism may be an insertion pin type or a screw type, but may be another type.

The premixer and combustor detailed above with reference to the drawings can be used in various configurations of gas generators and engines for gas turbines, for example not only the above configuration consisting of a gas generator and engine in the preceding stage. It can also be used with the variable outlet geometry examples shown in Figures 16-21D. Further, the present invention is
Similar to the single stage premixer engine shown in FIG. 19B, it can be used in annular and can-type combustor engines having multiple stage premixers.

Therefore, the scope of the present invention is not limited to the above embodiments, but is determined by the description of the claims and their equivalents.

[Brief description of drawings]

The accompanying drawings, which form a part of this specification, illustrate preferred embodiments of the invention and explain the principles of the invention.

FIG. 1A is a schematic cross-sectional view of a pre-stage gas turbine engine module using a fuel / air ratio controlled single-stage combustor system.

FIG. 1B is a schematic end view of the device shown in FIG. 1A viewed from the AA direction.

2 is a schematic end view of a pre-stage gas turbine engine module comprising another aspect of the combustor system shown in FIG. 1A.

3A is a detailed cross-sectional view showing a test version of a preferred component of the fuel / air premixer of the apparatus shown in FIG. 1A.

3B is a detailed cross-sectional view showing a test version of a preferred component of the fuel / air premixer of the apparatus shown in FIG. 1A.

3C is a detailed cross-sectional view showing a test version of a preferred component of the fuel / air premixer of the apparatus shown in FIG. 1A.

FIG. 4 is a detailed cross-sectional view showing an engine version of the fuel / air premixer shown in FIGS.

FIG. 5A is a schematic cross-sectional view of another pre-stage gas turbine engine module using a fuel / air ratio controlled single stage combustor system.

5B is a schematic cross-sectional view taken along the line 5B-5B in FIG. 5A.

FIG. 6 is a schematic cross-sectional view showing another structure of a premixer (without an integrated compressed air flow valve) used in the gas turbine engine module shown in FIG. 5A.

FIG. 7 is a schematic cross-sectional view illustrating yet another example of a pre-stage gas turbine engine module having a single stage combustor with a controlled fuel / air ratio.

FIG. 8 is a schematic cross-sectional view showing yet another example of a pre-stage gas turbine engine module having a single stage combustor with controlled fuel / air ratio.

8A is a schematic cross-sectional view of the premixer assembly taken along line 8A-8A of FIG.

9 is a schematic cross-sectional view showing the premixer assembly taken along line 9-9 of FIG.

9A is a schematic cross-sectional view showing a modified example (using a cylindrical air valve) of the premixer assembly shown in FIG. 9. FIG.

9B is a schematic cross-sectional view showing another modification of the premixer assembly shown in FIG. 9A.

10 is a perspective view of a preferred nozzle assembly for use with the engine module shown in FIGS. 8 and 9. FIG.

11 is a perspective cross-sectional view of the nozzle assembly of FIG.

FIG. 12 is a schematic cross-sectional view of another structure of the outlet nozzle of the premixer assembly.

FIG. 13 is a schematic cross-sectional view showing still another example of the pre-stage gas turbine engine module (having a can combustor).

FIG. 13A is an enlarged view of components of the air valve shown in FIG. 13.

13B is a schematic cross-sectional view of the nozzle of FIG. 13 taken along line 13B-13B.

FIG. 14A is a schematic cross-sectional view of yet another example of a fuel / air ratio controlled front stage gas turbine engine module having a single stage combustor.

FIG. 14B is a schematic perspective end view showing a portion of the engine module of FIG. 14A.

14C is a schematic cross-sectional view of the engine module component of FIG. 14B taken along line 14C -14C.

14D is a partially enlarged view of FIG. 14A showing the premixer assembly.

FIG. 15A is a schematic longitudinal cross-sectional view showing yet another example of a front stage engine having a single-stage combustor with a controlled fuel / air ratio.

FIG. 15B is a partial end view showing the embodiment of FIG. 15A.

FIG. 16 is a schematic cross-sectional view of a gas turbine module of the present invention having a mixing valve that controls the speed of the premixer outlet.

FIG. 17A is a detailed cross-sectional view showing another shape of the outlet member of the mixing valve.

FIG. 17B is a detailed cross-sectional view showing another mounting configuration for the embodiment of FIG.

FIG. 18A is a schematic sectional view showing still another example of the gas turbine engine module of the present invention.

FIG. 18B is a schematic cross-sectional view showing a modification (having a plurality of premixers) of the embodiment of FIG. 18A.

18C is a schematic cross-sectional view of the shape of FIG. 18B taken along the line segment AA.

FIG. 19A is a plan view schematically illustrating another example of the gas turbine engine of the present invention that uses a variable outlet geometry of the premixer to control the outlet velocity of the mixture, particularly for use with an annular combustor. is there.

FIG. 19B is a sectional view taken along the line segment 19B-19B.

FIG. 19C is a detailed view taken along the line 19B-19B.

FIG. 20A is a schematic diagram showing a modification of the premixer having the variable outlet geometry of FIGS. 19A-19C but adapted to a can combustor.

FIG. 20B is a schematic diagram illustrating a modification of the premixer having the variable outlet geometry of FIGS. 19A-19C but adapted to a can combustor.

FIG. 21A is a schematic partial cross-sectional view of a gas turbine engine combustor with yet another embodiment of a premixer having a variable outlet geometry that controls the exit velocity and dispersion angle of the exiting fuel / air mixture.

FIG. 21B is a detailed view of the outlet nozzle portion of the premixer shown in FIG. 21A.

FIG. 21C is a schematic partial cross-sectional view of a modification of the combustor and premixer shown in FIGS. 21A and 21B.

21D is a schematic partial cross-sectional view taken along line 21D-21D of FIG. 21C.

Claims (7)

[Claims] 1. A premixer device for mixing fuel and air to supply a fuel / air mixture, the premixer device having a shape for sucking and mixing the fuel and air, and discharging the inlet, the axis and the fuel / air mixture. A mixing pipe having an outlet and a mixing valve connected to the mixing pipe outlet, the mixing valve having coaxial inner and outer valve members, the ends of the inner and outer valve members having an outlet flow region. And the outlet flow region is formed by at least a notch in the outer valve member, the outlet flow region is formed in an opposite direction so as to form an angle with respect to the axis of the mixing valve, and the inner flow valve member and the outer valve member are formed. At least 1
One is a premixer device characterized in that it is relatively movable to selectively change the outlet basin. 2. The premixer device according to claim 1, wherein at least a part of the inner valve member is made of a ceramic material. 3. The premixer device according to claim 1, wherein the outer valve member is fixed and the inner valve member is movable. 4. A device for burning fuel and air, comprising:
An annular combustion chamber having an axis, and at least one premixer configured to receive fuel and air, the premixer having a venturi for mixing intake fuel and air to provide a fuel / air mixture, The venturi has an axis and the premixer has a fluid communication outlet to and from the combustion chamber for exiting a fuel / air mixture, the premixer outlet having an inner valve member and an outer valve member forming an outlet flow region. And at least said outer valve member has a notch positioned to direct a fuel / air mixture substantially tangentially to said opposing combustion chamber in said outlet basin for selectively varying said outlet basin At least the inner valve member is movable with respect to the outer valve member, thereby changing the outflow rate of the mixture. That the combustion device. 5. The combustion device according to claim 4, wherein the inner valve member and / or the outer valve member is made of a ceramic material. 6. A gas turbine engine comprising the combustion device according to claim 4. 7. Outflow rate and outflow of a fuel / air mixture out of a premixer device having a fuel / air mixing tube in communication with a fuel and compressed air supply, respectively, an axis and an outlet for outflowing the fuel / air mixture. A method for controlling direction, wherein a mixing valve provided at the outlet comprises an inner valve member and an outer valve member defining an outlet flow region, the fuel / angle forming an angle with respect to an axis of the outer valve member. The air mixture is allowed to flow in at least two opposite directions and the inner valve member is movable with respect to the outer valve member to change the outlet basin to increase or decrease the fuel / air mixture delivery rate. A method characterized by the following.