JP2018508733A - Turbine engine combustion assembly - Google Patents

Abstract

The present invention includes an annular flame tube (21) including a front wall (23), a rear wall (24), and a bottom (22) disposed opposite the engine shaft (30), and the engine shaft (30). An injection wheel (41) that is rotated and partially protrudes into the bottom (22) of the flame tube (21) and is configured to spray fuel onto the flame tube by centrifugation, and fuel on the injection wheel (41) A turbine engine combustion assembly (20) comprising: at least one injector (35) capable of depositing a film of said flame (21) on the front wall (23) or rear of the flame tube (21) The injection port (37) is disposed so as to pass through the upstream region of the wall (24), and the injection port (37) faces a part (43) of the injection wheel (41) located inside the flame tube (21). Characterized in that it opens into the flue (21), a turbine engine combustion assembly (20).

Description

  The present invention relates to the field of turbine engine combustion assemblies and, more particularly, to an apparatus for injecting fuel into the combustion chambers of these assemblies.

  Turbine engines typically have a fan, one or more compressor stages (eg, high and low pressure compressors), a combustion chamber, one or more, from upstream to downstream in the gas flow direction. A turbine stage (eg, a high pressure turbine and a low pressure turbine) and a gas exhaust nozzle are provided.

  FIG. 1 of the accompanying drawings schematically shows a longitudinal section of a combustion assembly 1 of one embodiment of a turbine engine according to the prior art.

  The combustion assembly 1 communicates with a compressor (not shown) that supplies air under pressure through a diffuser on the upstream side (left side of FIG. 1), and is connected to a distributor on the downstream side. (Not shown).

  The combustion assembly 1 is defined by an annular outer casing 2 and an inner casing 3, one extending along the longitudinal axis X-X 'inside the other.

  The combustion assembly 1 includes a “flame tube” or “combustion chamber” 4 that is a gas combustion field.

  The flame tube 4 is positioned between two casings, an outer casing 2 and an inner casing 3, and is provided with a rotating front wall 5 and a rear wall 6, the front wall 5 and the rear wall 6 generally having a longitudinal axis X. One extends entirely around the inside of the other around -X '.

  The front wall 5 and the rear wall 6 have a curved annular shape, the upstream side is connected to the inner casing 3 on both sides of the centrifugal injection wheel 7, and the downstream side is connected to the outer casing 2 and the inner casing 3, respectively. The

  This type of flame tube is called “annular” and extends around the longitudinal axis X-X ′ of the combustion assembly 1.

  The front wall 5 and the rear wall 6 are usually positioned at a distance from the outer casing 2 and the inner casing 3 and form an annular air supply duct 8 that surrounds the flame tube 4.

  The flame tube 4 comprises several successive zones from upstream to downstream, namely a primary zone 9 guided by the injection wheel 7 and an intermediate zone 10 at the bend in the tube. Several dilution tubes 11 are arranged.

  The air passes through a plurality of air intakes 12 provided through the front wall 5 and a plurality of air intakes 13 provided through the rear wall 6 facing a part of the primary zone 9. 4 invades.

  The centrifugal injection pipe 7 is attached to the engine shaft 15 and is rotationally driven by the engine shaft 15. The engine shaft 15 is coaxial with the longitudinal axis X-X ′ of the combustion assembly 1.

  The combustion assembly is also equipped with a plurality of injectors 16 that are regularly distributed around the engine shaft 15. These injectors 16 are positioned between the engine shaft 15 and the inner casing 3 that further constitutes the bottom (or “inside”) of the flame tube 4 (relative to the longitudinal axis X-X ′).

  Each injector 16 is positioned so as to inject fuel in the axial direction parallel to the longitudinal axis XX ′ (see arrow i) onto the front surface 17 of the injection wheel 7 which is the surface facing the upstream side of the combustion assembly 1. Is done.

  When the injection wheel 7 is driven to rotate, the fuel film in contact with the front surface 17 receives a centrifugal force and is displaced radially toward the outside of the wheel (see arrow j).

  A plurality of radially oriented holes 19 are formed at regular intervals in the annular peripheral edge 18 of the wheel 7.

  The fuel subjected to the centrifugal force passes through the hole 19 and is injected into the flame tube 4 in the radial direction with respect to the engine shaft 15 (arrow k), and atomized into very fine droplets. This is advantageous for mixing with the compressed air located there.

This type of combustion assembly with a centrifugal injection wheel has many advantages, especially for small engines such as helicopter engines. These advantages are as follows.
It is not necessary to have a preferred type of injector.
These injectors are not affected by the viscosity of the fuel in relation to the fuel type and ambient temperature.
The casing of the turbine is a simple structure with a low mass, resulting in a low cost.
A compromise between nitric oxide (NOx) on one side and carbon monoxide (CO) and unburned hydrocarbon (HC) emissions on the other side so that the exhaust emissions are the lowest emissions of all aero combustion systems Points are earned.

  However, this type of combustion assembly also has disadvantages related to the position of the injector located below the flame tube, close to the engine shaft, ie towards the interior of the combustion assembly. Currently, turbine engines are used in increasingly higher temperature rise cycles to reduce the specific fuel consumption that causes coking (ie, solidification) of the fuel. Therefore, to prevent failure (eg, shaft clogging due to solidified fuel ("coke"), premature wear due to insufficient fuel distribution, or engine start failure due to hindering fuel intake) and It is necessary to more frequently clean a large number of labyrinth seals positioned around it.

  Disassemble most of the turbine engine so that it can access the injectors in the central position, clean and / or replace them, and access the labyrinth seals positioned close to the injection wheel (hence the helicopter engine Need to be removed). In practice, it is not possible to change the injector when the engine is in place, which results in additional processing and cost and increases helicopter downtime.

  Furthermore, in the combustion assembly as shown in FIG. 1, it is necessary to leave sufficient space between the engine shaft 15 and the edge of the wheel 7 to place the injector 16, so that the diameter of the injection wheel is considerably large. That's it. As a result, this injection wheel has a considerable mass and is subjected to a considerable force due to the rotational speed.

  U.S. Pat. No. 4,040,251 describes a combustion assembly of the aforementioned type in which the injector and its supply tube are positioned within the thickness of the inner casing and the bottom of the flame tube. The spray port of the injector communicates with an opening provided at the bottom for passage of the injection wheel.

  Similar to the combustion assembly described above, access to the injector is difficult and therefore its maintenance is complex and costly.

U.S. Pat. No. 4,040,251

  The object of the present invention is to provide a combustion assembly of the type described above but which overcomes the above disadvantages.

  In particular, it is an object of the present invention to propose a combustion assembly in which the flame tube injector (s) can be easily disassembled without having to disassemble the entire turbine engine and remove it from the helicopter fuselage.

To achieve this object, the present invention is a turbine engine combustion assembly comprising:
An annular flame tube comprising: a front wall having an upstream zone facing upstream of the combustion assembly; a rear wall having an upstream zone facing upstream of the combustion assembly; and a bottom positioned opposite the engine shaft; ,
An injection wheel that is rotationally driven by the engine shaft coaxial with the longitudinal axis XX ′ of the combustion assembly, partially projects into the flame tube through the bottom and atomizes the fuel into the flame tube by centrifugal force An injection wheel configured as
At least one injector capable of depositing a fuel film on the injection wheel;
A combustion assembly comprising:

  According to the present invention, the injector passes through the upstream zone of the front wall of the flame tube or the upstream wall of the rear wall, and the flame of the injector faces a part of the injection wheel located in the flame tube. Positioned to enter the tube.

  These features of the present invention make it much easier to disassemble the injector because it is not necessary to access the area located between the bottom of the flame tube and the drive shaft of the injection wheel. This disassembly can take place where the machine (eg helicopter) with this combustion assembly is located.

  Advantageously, according to a first variant embodiment, the injector is positioned through an upstream zone of the front wall of the flame tube, and the injection wheel has an annular edge at its outer periphery upstream of the combustion assembly. The annular edge is perforated with a plurality of radial injection holes, and the injector enters the flame tube opposite the front surface of the annular peripheral edge of the injection wheel located in the flame tube.

  Advantageously, according to another variant embodiment, the injector is positioned through an upstream zone in the rear wall of the flame tube and the injection wheel has an annular edge at its outer periphery downstream of the combustion assembly The annular edge is formed with a plurality of radial injection holes, and the injector enters the flame tube opposite the rear surface of the annular peripheral edge of the injection wheel located in the flame tube.

  Advantageously, according to another variant embodiment, the injection wheel is solid and has a radial surface for receiving an annular fuel projecting into the flame tube, and the injector is located on the annular fuel receiving surface. Opposite into the flame tube.

  In a preferred case, the injector is oriented to inject fuel tangentially to the fuel receiving surface of the injection wheel.

  It is also possible for the fuel receiving surface of the injection wheel to form an angle α with the axis of the injection port of the injector, this angle α being between 90 ° and 180 °.

  According to a first variant, in the combustion assembly according to the invention, the injector axis of the injector includes a plane of the injection wheel and is a plane perpendicular to the central plane of the wheel perpendicular to the axis of the injection wheel. Extending into.

  According to a second variant, in the combustion assembly according to the invention, the axis of the injector nozzle is not perpendicular to the central plane of the wheel perpendicular to the axis of the injection wheel.

  The invention further relates to a turbine engine comprising a combustion assembly as described above.

  Other features and advantages of the present invention will become apparent from the description given with reference to the accompanying drawings, which illustrate different possible embodiments, by way of example and not limitation.

1 is a longitudinal cross-sectional view of a combustion assembly according to an embodiment of the prior art. 1 is a schematic longitudinal cross-sectional view of one embodiment of a turbine engine combustion assembly according to the present invention. FIG. 1 is a schematic longitudinal cross-sectional view of one embodiment of a turbine engine combustion assembly according to the present invention. FIG. FIG. 4 is a schematic view of the combustion assembly along the cross-section formed along line IV-IV in FIG. 3.

  A first embodiment of the present invention will be described with reference to FIG.

  This FIG. 2 is a schematic diagram of a combustion assembly 20 that is simplified with respect to the combustion assembly of FIG. 1 since only the flame tube and injection assembly are shown.

  The flame tube 21 includes a bottom 22 (or the inside of the flame tube), a front wall 23, and a rear wall 24. The bottom 22 connects the front wall 23 and the rear wall 24.

  With respect to the aforementioned combustion assembly 1, the flame tube 21 is annular and extends around the longitudinal axis X-X ′ of the combustion assembly 20.

  In the bottom portion 22, an opening 25 through which a part of the injection wheel 26 is passed into the flame tube 21 is opened. In other words, the injection wheel 26 partially protrudes toward the bottom of the flame tube 21.

  The front wall 23 has an upstream zone 230 upstream of the combustion assembly and turbine engine (left side of FIG. 2) with a plurality of inlets 27 open to the flame tube primary combustion zone 28.

  Similarly, the rear wall 24 has an upstream zone 240 facing the upstream side of the combustion assembly and turbine engine and having a plurality of inlets 29 open to the primary combustion zone 28 of the flame tube.

  The injection wheel 26 is rotationally driven by an engine shaft 30 that is coaxial with the longitudinal axis X-X '. The injection wheel 26 has a front surface 31 facing the upstream side of the combustion assembly and an opposing rear surface 32 facing the downstream side.

  The outer periphery of the injection wheel 26 is curved and an annular peripheral edge 33 in which holes 34 oriented radially with respect to the longitudinal axis XX ′ of the combustion assembly 20 are preferably opened at regular intervals. Is defined. These holes 34 can be orifices or slots.

  Compared to the prior art injection wheel 7 (see FIG. 1), not only is the annular peripheral edge 33 of the injection wheel 26 completely inside, but also the peripheral edge 260 of the disc-like part that constitutes the injection wheel 26 is also inward. It should be noted that the injection wheel 26 further penetrates the inside of the flame tube 21. This annular portion 260 is located at an extension of the edge 33.

  Therefore, the inner surface of the annular edge portion 33 is located at a distance D1 from the bottom portion 22 of the flame tube 21, and a part thereof faces the engine shaft 30.

  The combustion assembly further comprises one or more injectors 35, only one of which is shown in FIG.

  The injector 35 is connected to a fuel supply pipe 36, and the fuel supply pipe 36 itself is connected to a fuel source (not shown).

  The injector 35 has an injection port 37.

  Unlike the prior art, the injector 35 is positioned to pass through the front wall 23 of the flame tube 21, preferably the upstream zone 230, where the inlet 27 is provided. Further, the injector 35 is positioned so that the injection port 37 communicates with the inside of the flame tube 21.

  To that end, it should be noted that the distance D1 is sufficient to allow the passage of the fuel jet exiting the injection end 37 of the injector 35.

  The injection operation is as follows. The fuel exiting the injector 35 exits through the injection port 37 and is injected into the front surface 31 of the part 260 of the injection wheel 26, where a fuel film F is formed.

  Under the influence of centrifugal force due to the rotation of the injection wheel 26, the fuel film is displaced toward the outer periphery of the wheel, contacts with the air surrounding the wheel, and very fine droplets G dispersed inside the flame tube 21. Pass through the holes 34 which have the effect of atomizing or atomizing the fuel.

  Positioning the injector 31 through the front wall 23 of the flame tube facilitates disassembly of the injector. Preferably, the configuration is adapted so that the injector 31 can be extracted through this front wall 23.

  Also advantageously, the diameter of the injection wheel 26 is smaller than the diameter of the prior art injection wheel shown in FIG. 1 because the bottom 22 of the flame tube 21 can be located closer to the engine shaft 30. In this regard, it should be noted that FIGS. 1 and 2 are not shown to scale.

  The mass of the injection wheel 26 having a smaller diameter is smaller than the mass of the prior art wheel, so that the mechanical strength is also improved.

  Another embodiment of the invention is described with reference to FIG. The same elements are given the same reference numbers and will not be described again in detail.

  The injection wheel has the reference number 41. The injection wheel is rotationally driven by the engine shaft 30.

  The injection wheel is different from the injection wheel 26 in that it is solid, that is, the injection hole 34 is not opened. The peripheral edge 42 projects to receive a fuel film F so as to define a circular radial surface 43 (preferably flat).

  The injector 35 is positioned so that its injection port 37 faces this surface 43.

  The axis of the injection port 37 forms an angle α (alpha) with the fuel receiving surface 43. This angle α is advantageously between 90 ° and 180 °. When the angle α is 180 °, fuel injection occurs tangential to the surface 43.

  In this case, considering that the center plane P of the wheel (41) is perpendicular to the axis of the engine shaft 30 that drives the wheel, the axis of the injection port 37 of the injector 35 is perpendicular to P and the engine shaft. It extends in a plane P1 containing 30 axes. In FIG. 3, the plane P1 corresponds to the plane of the drawing sheet, and in FIG. 4, the plane P1 is indicated by a one-dot chain line.

  However, it is possible to orient so that the axis of the injection port 37 does not become perpendicular to P. That is, in this case, this axis protrudes or leaves from the plane P1 corresponding to the plane of FIG. In FIG. 4, this axis is referred to as X1-X'1.

  Note that in this embodiment, the injector 35 is advantageously not inserted deeper into the flame tube 21 than in the embodiment of FIG. This is because it is not necessary for the injection port to reach a zone located below the annular edge 33 of the injection wheel. The injector need only be able to inject fuel onto the surface 43. This facilitates disassembly of the injection 35.

  As described above, the fuel film F receives the centrifugal force generated by the wheel 41 and is atomized into the shape of the fuel droplet G.

  This embodiment of the invention makes it possible to have an injection wheel 41 with a structure that is very simple and excellent in mechanical durability, since no through holes are drilled. Since the bottom 22 of the flame tube 21 can be brought closer to the engine shaft 30, the diameter of the injection wheel 41 is also smaller than in the prior art. Finally, combustion occurs substantially only on one side of the injection wheel 41, on the left side in FIG.

  Furthermore, it should be noted that alternative embodiments of the present invention are possible. In particular, the injector 35 can be positioned through the rear wall 24 of the flame tube 21, preferably through the upstream zone 240 of the flame tube 21.

  In this case, when the injection wheel 26 is made according to the embodiment of FIG. 2, its annular edge 33 is bent downstream of the combustion assembly 20 and fuel injection occurs on the rear surface 32 of the wheel.

  When the injector is positioned through the rear wall 24 and the injection wheel 41 follows the embodiment of FIG. 3, its receiving surface 43 is directed towards the rear wall 24.

  Different possible inclinations of the axis of the injection port 37 and the different values of the angle α mentioned above also apply to this variant embodiment.

  Finally, according to another alternative embodiment, the flame tube 21 can be made of several parts that are assembled using a flange 50 that facilitates disassembly.

Claims (9)

A front wall (23) having an upstream zone (230) facing upstream of the combustion assembly (20); and a rear wall (24) having an upstream zone (240) facing upstream of the combustion assembly (20); An annular flame tube (21) comprising a bottom (22) positioned opposite the engine shaft (30);
An injection wheel (26, 41) driven by the engine shaft (30) coaxial with the longitudinal axis XX ′ of the combustion assembly (20), through the bottom (22) and through the flame tube (21 ) And an injection wheel (26, 41) configured to partially atomize within the flame tube and to atomize the fuel into the flame tube by centrifugal force;
At least one injector (35) capable of depositing a fuel film on the injection wheel (26, 41);
A turbine engine combustion assembly (20) comprising:
The injector (35) passes through the upstream zone (230) of the front wall (23) of the flame tube (21) or the upstream zone (240) of the rear wall (24), and the injection port (37) Turbine engine, characterized in that it is positioned to enter the flame tube (21) opposite a part (260, 43) of the injection wheel (26, 41) located in the flame tube (21) Combustion assembly (20).   The injector (35) is positioned through the upstream zone (230) of the front wall (23) of the flame tube (21), the injection wheel (26) has an annular edge (33) at its outer periphery. To be curved upstream of the combustion assembly, the annular edge (33) is provided with a plurality of radial injection holes (34), and the injector (35) is connected to a flame tube ( Combustion assembly (20) according to claim 1, characterized in that it enters the flame tube (21) opposite the front face (31) of the annular peripheral edge (260) of the injection wheel located in 21). .   The injector (35) is positioned through the upstream zone (240) of the rear wall (24) of the flame tube (21), the injection wheel (26) has an annular edge (33) at its outer periphery. To be curved downstream of the combustion assembly, the annular edge (33) is provided with a plurality of radial injection holes (34), and the injector (35) is connected to a flame tube ( 21. Method according to claim 1, characterized in that it enters the flame tube (21) opposite the rear face (32) of the annular peripheral edge (260) of the injection wheel located within 21).   The injection wheel (41) is solid and has a radial surface (43) for receiving annular fuel protruding into the flame tube (21), and the injector (35) is an annular fuel receiving surface (43). Combustion assembly according to claim 1, characterized in that it enters the flame tube (21) opposite to the flame.   The combustion assembly according to claim 4, characterized in that the injector (35) is oriented to inject fuel tangentially to the fuel receiving surface (43) of the injection wheel.   The fuel receiving surface (43) of the injection wheel (41) forms an angle α with the axis of the injection port (37) of the injector (35), and this angle (α) is 90 ° to 180 °. A combustion assembly according to claim 4.   The axis of the injection port (37) of the injector (35) includes the axis (30) of the injection wheel (41) and is perpendicular to the axis of the injection wheel (41) relative to the central plane (P) of the wheel (41) Combustion assembly according to any one of claims 4 to 6, characterized in that it extends in a plane (P1) that is vertical.   The axis of the injection port (37) of the injector (35) is not perpendicular to the central plane (P) of the wheel (41) perpendicular to the axis of the injection wheel (41). The combustion assembly according to claim 6.   A turbine engine comprising the combustion assembly according to any one of claims 1 to 8.

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