JPH08178288A - Fuel nozzle - Google Patents

Abstract

PURPOSE: To provide fuel spray for generating a desired temperature gradient forward of a turbine section and to obtain the desired spread of fuel in radial and circumferential directions by improving the fuel injection of the secondary fuel circuit of the fuel nozzle of a gas turbine engine. CONSTITUTION: The radial jet of the fuel nozzle 22 of the burner of a gas turbine engine is disposed non-axially symmetrically around the end of the nozzle so as to reduce a pattern factor by non-uniformly distributing fuel in the circumferential direction in an air swirler 26.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to fuel nozzles for combustors of gas turbine engines.

[0002]

BACKGROUND OF THE INVENTION A typical gas turbine engine combustor fuel nozzle includes a primary fuel circuit and an independent secondary fuel circuit that operates independently during high power engine operation. As is well known, the secondary fuel circuit may include its own fuel nozzle or may be included in a fuel nozzle incorporating a primary fuel circuit.

In the latter structure, the secondary fuel circuit is a single orifice arranged concentrically with the orifice of the primary fuel circuit and coaxial with the axis of the tip of the fuel nozzle. Other fuel nozzle constructions include multiple orifices concentrically and symmetrically spaced about the axis of the nozzle tip, which is industrially referred to as a radial jet.

Generally, the high power fuel flow enters the burner through a secondary fuel circuit. A typical secondary fuel circuit produces a symmetrical fuel distribution around the coincident axes of the air swirler and the fuel nozzle tip. In all of these secondary fuel circuits, it is necessary to achieve the fuel spray penetrating force into the air swirl generated by the air swirler of the fuel nozzle and prevent the fuel spray from weakening caused by the air swirler. Since these requirements have been improved, multiple secondary fuel orifices (radial jets) have been for improvements on a single secondary fuel orifice. Both the single orifice and radial jet structures of the secondary fuel circuit, as described above, are adapted to produce fuel distribution downstream of the air swirler of the fuel nozzle in the form of a symmetrical spray.

In order for a combustor to be effective, the combusted gas medium must exhibit the desired pattern factor (pattern coefficient or pattern rate) before it is delivered to the engine gas turbine. I won't. One conventional way to reduce pattern factors has been to incorporate mixing air holes in the combustor to mix additional air with the combustion products. Due to the increased amount of air entering the combustor through the front end, the ability to use the air jets in the mixing zone to validate the pattern factor is diminished. The problems are also exacerbated for advanced gas turbine combustors due to increased combustor size and airflow.

Appropriate use of radial jets by the inventor has shown that the combustor does not adversely affect the spray penetration force and adversely affect the ability to prevent fuel spray decay caused by the air swirler. Advanced gas turbines by adapting the fuel distribution during high power to reduce the pattern factor of
It has been discovered that the pattern factor of the engine can be improved. The present invention contemplates the radial jets being arranged asymmetrically to produce a fuel spray suitable for producing the desired temperature distribution at the end of the combustor upstream of the turbine inlet.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to improving fuel injection in a secondary fuel circuit of a fuel nozzle of a gas turbine engine.

[0008]

SUMMARY OF THE INVENTION A feature of the present invention is that it provides a fuel spray that produces a predetermined temperature gradient in front of a turbine section of a gas turbine engine, with a nozzle tip and an axis about the air swirler. Arrangement of multiple radial jets asymmetrically with respect to one fuel nozzle.

Another feature of the present invention is to properly arrange a plurality of radial jets for one fuel nozzle in order to obtain a predetermined fuel spread in the radial and circumferential directions.

The above and other features of the present invention will be apparent from the following examples and the accompanying drawings.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

As mentioned above, in a gas turbine engine fuel system with separate primary and secondary circuits, fuel enters the combustor through the secondary circuit for high power engine operation. In conventional fuel nozzle designs, fuel was distributed symmetrically about the same axis of the air swirler and the fuel nozzle tip. Such fuel nozzles are described, for example, in J. E. FIG. Faucher
U.S. Pat. No. 4,411, assigned to the applicant
No. 8,543 (the title of the invention is "fuel nozzle for gas turbine engine"). The fuel nozzle serves to distribute the fuel burning in the burner to achieve effective combustion while avoiding the production of smoke and toxic gases injected into the atmosphere.

The present invention finds use in an annular combustor, but is not so limited and may be used in other types of combustors. However, the present invention relates only to fuel nozzles that use a secondary fuel circuit in addition to the primary fuel circuit and operate during high power conditions of the combustor operating envelope.

As shown schematically in FIG. 1, an annular combustor (annular combustor) 10 includes a cylindrical or conical outer liner member 12 forming a combustion chamber 16 and a cylindrical or conical inner liner. It consists of the member 14. Although not shown in detail, the liner members 12 and 14 are provided in the diffuser case 18
The fuel nozzle 22 is supported by a dome 20 attached to the front ends of the outer liner member 12 and the inner liner member 14 which form the end walls.
As is usual in these installations, the fuel nozzles are mounted in an air swirler (air swirler) 26 for mixing air and fuel to obtain sufficient combustion.
Other details of the combustor and support mechanisms are described in H. H., November 22, 1988. G. It is described in US Pat. No. 4,785,623 assigned to Reynolds and assigned to the applicant.

As mentioned above, in advanced engine technology, the fuel nozzle has a central orifice at the tip for injecting fuel from the primary fuel circuit and a central tip for injecting fuel from the secondary fuel circuit. It is designed to have multiple radial jets circumferentially spaced around the orifice. The effect of this design will be understood by reference to the three graphs of Figures 2 and 3. As described above, the plurality of radial jets formed around the tip of the fuel nozzle 22 mounted in the air swirler 26 are arranged at equal intervals in the circumferential direction. The fuel distributions shown in the three graphs of FIG. 3 are plots of fuel extending radially outward from the centerline of the tip through three planes identified as plane A, plane B and plane C. As can be seen from these graphs, the fuel in each plane is distributed exactly the same. This fuel distribution is then compared to the fuel distribution obtained from a fuel nozzle designed according to the present invention and it can be seen that the fuel distribution is different in each of the planes A, B and C (the same in all figures Have the same reference number).

In FIG. 4, the radial jet 28 is
The fuel nozzles 22 are arranged non-axially symmetrically around the tip of the fuel nozzle 22. The same planes A, B and C taken from end to end of the air swirler and tip centerline D of FIG.
You can see that the fuel is unevenly distributed.
In accordance with the present invention, by appropriately selecting the location of the radial jet 28, fuel is distributed within the burner,
It is possible to create a more desirable temperature distribution at the combustor outlet. This effect is shown in FIG. 1, where curve H shows the temperature profile produced by a conventional radial jet (FIG. 2) and curve G shows the case of using an asymmetric radial jet (FIG. 4). The temperature profile is shown. Compared with curve G, curve H
Show that a non-axisymmetric arrangement of radial fuel jets can be used to flatten the temperature profile. There is a relationship between the combustion gas outlet temperature and the pattern factor that a flatter temperature profile reduces the pattern factor, ie, sharpness. Therefore, it can be seen from the above that by selecting the number of radial jets and their circumferential position, a fuel distribution can be obtained which increases the pattern factor and improves the effectiveness of combustion. The pattern factor can be expressed mathematically, and for the purposes of the present invention, the pattern factor is defined as the amount of difference between the maximum combustor outlet temperature and the average combustor outlet temperature related to the average temperature rise. It

The present invention also has other advantages in annular combustors by controlling the spread of fuel.
For combustors where the combustor wall was equidistant from the fuel injector, fuel spread was not a factor. When the wall distance is constant, the fuel spread in the radial and circumferential directions of the engine is clearly the same, and it is not necessary to consider the fuel spread. However, some annular burners have unequal radial and circumferential spreads. Obviously, the radial spread is determined by the height of the combustor dome, and the circumferential spread is controlled by the distance between adjacent injectors.

Therefore, the circular hollow conical fuel spray of the type emitted from the fuel nozzle disclosed in US Pat. No. 4,418,543 may not be optimal for annular burners. Attempts have been made to use elliptical air swirlers to increase circumferential spread without affecting radial penetration. However, an elliptical air swirler is undesirable for at least two reasons: That is, 1) it is more difficult to manufacture than a circular air swirler, and 2) it is difficult to maintain the angular momentum of the air in the non-circular passage, which facilitates the distribution of air from the elliptical air swirler. This is because it cannot be processed.

As is apparent from FIG. 5, the present invention allows radial jets to be arranged to enhance fuel spread. As shown in FIG. 6, a large number of fuel nozzles 22 are supported in the dome 20 in the circumferential direction.
Obviously, the distance between the centerlines of adjacent fuel nozzles and the distance from the centerline of the fuel nozzles to the radial wall of the dome are not equal. In accordance with the present invention, the radial jets are non-axisymmetrically spaced about the centerline of the fuel nozzle to ensure this difference and reduce the pattern factor in the combustor.

[0020]

As described above, according to the present invention, by arranging a plurality of radial jets asymmetrically about one fuel nozzle around the nozzle tip of the gas turbine engine and the axis of the air swirler, A fuel spray may be provided in front of the turbine section of the turbine engine that produces the desired temperature gradient. Further, according to the present invention, by appropriately disposing a plurality of radial jets for one fuel nozzle, it is possible to obtain a desired fuel spread in the radial direction and the circumferential direction.

[Brief description of drawings]

1 is a partial cross-sectional schematic view showing an annular combustor of a gas turbine engine and a potential temperature profile according to the present invention.

FIG. 2 is a schematic diagram of a secondary fuel circuit of a conventional radial jet fuel nozzle.

3 is a series of graphs showing fuel distribution at various faces of the radial jet fuel nozzle of FIG.

FIG. 4 is a schematic diagram of a secondary fuel circuit of a radial jet fuel nozzle according to the present invention.

5 is a series of graphs showing fuel distribution at various faces of the radial jet fuel nozzle of FIG.

FIG. 6 is a partial schematic view of a plurality of radial jet fuel nozzles attached to the front end of a combustor.

[Explanation of symbols]

 10 ... Annular combustor 12 ... Outer liner member 14 ... Inner liner member 16 ... Combustion chamber 18 ... Diffuser case 20 ... Dome 22 ... Fuel nozzle 26 ... Air swirler 28 ... Radial jet

Claims (5)

[Claims] 1. A fuel nozzle having a primary fuel circuit and a secondary fuel circuit for a combustor of a gas turbine engine, the front nozzle facing the combustor, and the fuel nozzle disposed in the front surface on a central axis of the fuel nozzle. A cylindrical body having a central orifice for introducing fuel from the primary fuel circuit into the combustor; and a cylindrical body disposed in the front surface in a radial direction with respect to the central axis of the fuel nozzle and from the secondary fuel circuit to the combustor. Means for producing a predetermined pattern factor including a plurality of orifices for introducing fuel into the radial direction, wherein the plurality of radially arranged orifices are unevenly arranged in the circumferential direction of the fuel nozzle. The flow of fuel from a plurality of orifices disposed in the combustor distributes the fuel non-axisymmetrically within the combustor to produce a predetermined pattern factor. And a fuel nozzle. 2. The fuel nozzle according to claim 1, wherein an air swirler is concentrically attached to the fuel nozzle. 3. The combustor is an annular combustor having a dome, the dome forming an end wall at a front end of the annular combustor and supporting a fuel nozzle in an opening formed in the dome. The fuel nozzle according to claim 2, characterized in. 4. The fuel nozzle, wherein the combustor has a concentrically arranged inner and outer liner forming the combustion chamber, the dome being mounted within an opening formed in the dome. Having the same multiple fuel nozzles,
The plurality of fuel nozzles are arranged at equal intervals in the circumferential direction,
The distance between the central axes of adjacent fuel nozzles is different from the distance between the central axes of one of the plurality of fuel nozzles relative to the radial extent of the inner or outer liner,
The distances over which the fuel spreads in the radial direction and the circumferential direction are not equal, and the plurality of orifices arranged in the radial direction unevenly distributes the fuel from the secondary fuel circuit, resulting in uniform fuel spray in the radial direction and the circumferential direction. Cause a predetermined pattern
The fuel nozzle according to claim 3, wherein a factor is obtained. 5. A fuel nozzle device having a plurality of fuel nozzles, each fuel nozzle having a primary fuel circuit and a secondary fuel circuit of a combustor of a gas turbine engine, wherein the combustor forms a combustion chamber. A dome surrounding the front end of the combustion chamber at the front ends of the inner and outer liners, the dome supporting the plurality of fuel nozzles. Each of the plurality of fuel nozzles has a front surface facing the combustion chamber, and a fuel cell is arranged in the center axis of the fuel nozzle in the front surface to supply fuel from the primary fuel circuit to the combustion chamber. A central orifice to be introduced, wherein the fuel nozzle device is arranged in the front surface radially arranged with respect to the central axis of the fuel nozzle. Means for producing a predetermined pattern factor including a plurality of orifices for introducing fuel from a fuel circuit into the combustion chamber, wherein the plurality of radially arranged orifices are non-uniformly arranged in a circumferential direction of the fuel nozzle. And the flow of fuel from the plurality of orifices arranged in the radial direction distributes the fuel in the combustor in a non-axisymmetric manner to generate a predetermined pattern factor. The distance between the central axes of adjacent fuel nozzles is different from the distance between the central axes of one of the plurality of fuel nozzles with respect to the radial spread of the inner liner or the outer liner. The fuel spreads from the secondary fuel circuit of the plurality of orifices arranged in the radial direction unequal in the direction in which the fuel spreads in the circumferential direction and the circumferential direction. And wherein the resulting uniform fuel spray in the radial and circumferential directions by distribution, fuel nozzle device.