EP3245452A1

EP3245452A1 - Turbine engine combustion assembly

Info

Publication number: EP3245452A1
Application number: EP16701838.1A
Authority: EP
Inventors: Lorenzo Huacan Hernandez; Nicolas SAVARY
Original assignee: Safran Helicopter Engines SAS
Current assignee: Safran Helicopter Engines SAS
Priority date: 2015-01-15
Filing date: 2016-01-12
Publication date: 2017-11-22
Also published as: CA2971988A1; FR3031767A1; KR20170104517A; CN107208897A; FR3031767B1; JP2018508733A; US20170370591A1; WO2016113495A1; RU2017127312A

Abstract

The invention relates to a turbine engine combustion assembly (20), which includes: an annular flame tube (21) including a front wall (23), a rear wall (24) and a bottom (22) arranged facing an engine shaft (30); an injection wheel (41) rotated by said engine shaft (30), partially projecting into the bottom (22) of the flame tube (21) and configured such as to spray fuel into the flame tube by centrifugation; and at least one injector (35), capable of depositing a film of fuel on said injection wheel (41), said combustion assembly being characterised in that said injector (35) is arranged so as to pass through said upstream area of the front wall (23) or the rear wall (24) of the flame tube (21), so that the injection opening thereof (37) opens into said tube (21), opposite the portion (43) of said injection wheel (41) which is located inside said flame tube (21).

Description

Turbomachinery combustion assembly

GENERAL TECHNICAL FIELD

The invention relates to the field of combustion assemblies for turbomachines, and more particularly the fuel injection devices in the combustion chamber of these assemblies.

STATE OF THE ART

A turbomachine generally comprises, from upstream to downstream, in the direction of flow of the gases, a fan, one or more stages of compressors, for example a high pressure compressor and a low pressure compressor, a combustion chamber, one or more turbine stages, for example a high pressure turbine and a low pressure turbine, and a gas exhaust nozzle.

Figure 1 attached schematically illustrates a longitudinal sectional view of the combustion assembly 1 of an embodiment of a turbomachine according to the prior art.

The combustion assembly 1 is in upstream communication (on the left in FIG. 1) with a compressor (not shown), which supplies it with pressurized air via a diffuser, and is connected in downstream, to a distributor itself connected to a high pressure turbine (not shown in the figures).

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

The combustion assembly 1 comprises a "flame tube" or "combustion chamber" 4 which is the seat of the combustion of the gases.

The flame tube 4 is arranged between the two outer casings 2 and inner 3 and is provided with walls of revolution before 5 and rear 6 which extend globally one inside the other around the longitudinal axis XX '.

The front and rear walls 5 and 6 have an annular bent shape and are connected, upstream, to the inner casing 3, on either side of a centrifugal injection wheel 7, and downstream, to the outer casing 2 and to the inner casing 3 respectively. This type of flame tube is called "annular" and extends around the longitudinal axis XX 'of the combustion assembly 1.

The front and rear walls 5 and 6 are generally arranged at a distance from the outer and inner casings 2 and 3, so as to form an annular air supply duct 8 surrounding the flame tube 4.

The flame tube 4 comprises several successive zones from upstream to downstream, namely a primary zone 9 into which the injection wheel 7 opens and an intermediate zone 10 at the elbow of the tube, in which there are several dilution pipes 1 1.

The air enters the flame tube 4 through a plurality of air inlet ports 12 formed through the front wall 5 and a plurality of air inlet openings 13 formed through the rear wall 6, facing a portion of the primary zone 9.

The centrifugal injection wheel 7 is mounted on a drive shaft 15, and is rotated by it. The drive shaft 15 is coaxial with the longitudinal axis X-X 'of the combustion assembly 1.

The combustion assembly 1 is furthermore equipped with a plurality of injectors 16 distributed regularly around the drive shaft 15. These injectors 16 are arranged between the drive shaft 15 and the inner housing 3 which also constitutes the bottom (or "inner side") of the flame tube 4 (relative to the longitudinal axis X-X ').

Each injector 16 is arranged to project fuel axially, (see arrow i), parallel to the longitudinal axis X-X ', on the front face 17 of the injection wheel 7, that is to say the face facing upstream of the combustion assembly 1.

As the injection wheel 7 is rotated, the fuel film which comes into contact with the front face 17 is subjected to the centrifugal force and moves outwardly of the wheel radially, (see arrow j).

The annular peripheral rim 18 of the wheel 7 is pierced at regular intervals, with a plurality of radially oriented slots 19.

The fuel subjected to the centrifugal force passes through the slots 19 and is projected radially relatively to the drive shaft 15, in the flame tube 4 (arrow k) and is atomized into very fine droplets, which promotes its mixing with the compressed air that is there. This type of combustion assembly with centrifugal injection wheel has many advantages, especially for small engines, such as helicopter engines. These advantages are:

it is not necessary to have a preferred type of injector,

these injectors are not very sensitive to the viscosity of the fuel, which is itself related to the type of fuel or to the ambient temperature,

the casing of the turbine is of a simple structure and of low mass and consequently of low cost,

it is possible to reach a compromise between the emissions of nitric oxide (NOx) on the one hand, and the emissions of carbon monoxide (CO) and unburned hydrocarbons (HC) on the other hand, which is These emissions are among the lowest of any aviation combustion system.

However, this type of combustion assembly also has drawbacks, related to the position of the injectors, which are placed under the flame tube, near the motor shaft and thus towards the inside of the combustion assembly. However, turbomachines are used with increasingly high temperature rise cycles to reduce their specific consumption, which causes a coking (that is to say, solidification) of the fuel. It is therefore necessary to clean more frequently the injection system and the many labyrinth seals arranged around, to avoid malfunctions (such as for example the blocking of the shaft by the solidified fuel ("coke") , premature wear of hot parts due to poor fuel distribution, or failure to start the engine due to blockage of the fuel supply).

It is then necessary to disassemble a large part of the turbomachine (and therefore to remove the engine from the helicopter) in order to access the centrally located injectors, to clean and / or replace them and to access the labyrinth seals arranged near the injection wheel. It is not possible to change the injector when the engine is in place, which leads to handling and additional costs and increases the period of immobilization of the helicopter.

In addition, in the combustion assembly such as that shown in Figure 1, the diameter of the injection wheel is important, since it is necessary to leave sufficient space between the drive shaft 15 and the edge of the wheel 7, to arrange the injectors 16. As a result, this injection wheel has a large mass and is subjected to high stresses due to the speed of rotation.

US 4,040,251 discloses a combustion assembly of the aforementioned type, wherein the injector and its feed tube are arranged in the thickness of the inner housing and the bottom of the flame tube. The spray orifice of the injector opens into the opening in the bottom for the passage of the injection wheel.

As for the combustion assembly described above, access to the injector is difficult and maintenance is therefore complex and expensive.

PRESENTATION OF THE INVENTION

The invention aims to provide a combustion assembly of the aforementioned type, which retains the above advantages, but which solves the disadvantages mentioned above.

The object of the invention is notably to propose a combustion assembly in which the nozzle or injectors of the flame torch are easily removable, without it being necessary to dismantle the whole of the turbomachine and to remove it from the fuel cell. the helicopter.

For this purpose, the invention relates to a turbomachine combustion assembly, comprising:

an annular flame tube, comprising a front wall provided with an upstream zone facing upstream of the combustion assembly, a rear wall provided with an upstream zone facing upstream of the combustion assembly and a bottom disposed opposite a motor shaft,

an injection wheel driven in rotation by said drive shaft coaxial with the longitudinal axis XX 'of the combustion assembly, this injection wheel partially projecting into the flame tube through its bottom, and being configured for spraying fuel into the flame tube by centrifugation,

at least one injector, capable of depositing a film of fuel, on said injection wheel.

According to the invention, said injector is disposed through said upstream zone of the front wall or through said upstream zone of the rear wall of the flame tube and so that its orifice injection opens into this tube, facing the portion of said injection wheel which is in said flame tube.

Thanks to these features of the invention, it is much easier to disassemble the injectors, since it is no longer necessary to have access to the area between the bottom of the flame tube and the drive shaft. the injection wheel. This disassembly can be performed at the location where the device (for example the helicopter) equipped with this combustion assembly is located.

Advantageously and according to a first embodiment, said injector is disposed through the upstream zone of the front wall of the flame tube, said injection wheel is bent at its periphery, upstream of the assembly of combustion, so as to have an annular rim, this annular flange is pierced with several radial injection ports and said injector opens into the flame tube facing the front face of the annular peripheral portion of said injection wheel which is found in the flame tube.

Advantageously and according to another alternative embodiment, said injector is disposed through the upstream zone of the rear wall of the flame tube, said injection wheel is bent at its periphery, downstream of the assembly of combustion, so as to have an annular rim, this annular flange is pierced with several radial injection ports and said injector opens into the flame tube opposite the rear face of the annular peripheral portion of said injection wheel which is found in the flame tube.

Advantageously and according to yet another alternative embodiment, said injection wheel is solid and has a radial annular surface for receiving the fuel which protrudes into the flame tube and the injector opens into the flame tube, opposite of this annular face of receiving the fuel.

In this case preferably, the injector is oriented so as to project the fuel tangentially on said fuel receiving face of the injection wheel.

It is also possible that the fuel receiving face of the injection wheel forms an angle α with the axis of the injection orifice of the injector, this angle (a) being between 90 ° and 180 ° .

According to a first variant, in the combustion assembly according to the invention, the axis of the injection orifice of the injector extends in a plane which both includes the axis of the injection wheel and is perpendicular to the median plane of the wheel perpendicular to the axis of the injection wheel.

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

The invention also relates to a turbomachine comprising a combustion assembly as mentioned above.

PRESENTATION OF FIGURES

Other features and advantages of the invention will appear from the description which will now be made, with reference to the accompanying drawings, which represent, by way of indication but not limitation, various possible embodiments.

On these drawings:

FIG. 1 is a longitudinal sectional view of a combustion assembly according to an embodiment of the prior art,

FIGS. 2 and 3 are diagrammatic views, in longitudinal section, of two embodiments of a combustion assembly of a turbomachine according to the invention,

FIG. 4 is a schematic view of the combustion assembly, taken along a sectional plane represented by the line IV-IV in FIG.

DETAILED DESCRIPTION

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

This Figure 2 is a diagram of a combustion assembly 20 which is simplified with respect to that of Figure 1, since it represents only the flame tube and the injection assembly.

The flame tube 21 comprises a bottom 22 (or inner side 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.

As for the preceding combustion assembly 1, the flame tube 21 is annular and extends around the longitudinal axis X-X 'of the combustion assembly 20.

The bottom 22 is pierced with an opening 25 allowing the passage of a portion of the injection wheel 26 inside the flame tube 21. in other words, the injection wheel 26 is partly protruded in the bottom of the flame tube 21.

The front wall 23 has an upstream zone 230, facing upstream of the combustion assembly and the turbomachine (on the left in FIG. 2), pierced with a plurality of air inlet orifices 27, facing the primary combustion zone 28 of the flame tube.

Similarly, the rear wall 24 has an upstream zone 240, facing upstream of the combustion assembly and the turbomachine, pierced with a plurality of air inlet orifices 29, opposite the zone primary combustion 28 of the flame tube.

The injection wheel 26 is rotated by the drive shaft 30, coaxial with the longitudinal axis X-X '. It has a front face 31, facing upstream of the combustion assembly and an opposite rear face 32, facing downstream.

This injection wheel 26 is bent at its periphery, so as to define an annular peripheral rim 33, pierced, preferably at regular intervals, by slots 34 oriented radially with respect to the longitudinal axis XX 'of the assembly. 20. These lights 34 may be orifices or slots.

Compared to the injection wheel 7 of the state of the art

(see FIG. 1), it will be noted that the injection wheel 26 penetrates further inside the flame tube 21 since not only is its annular peripheral rim 33 therein in full, but also an annular peripheral portion 260 of the disk which constitutes the wheel 26. This annular portion 260 is located in the extension of the rim 33.

The inner face of the annular flange 33 is thus at a distance D1 from the bottom 22 of the flame tube 21 which is itself facing the drive shaft 30.

The combustion assembly also comprises one or more injectors 35, only one of which is visible in FIG. 2.

This injector 35 is connected to a fuel supply tube 36 itself connected to a fuel source not shown in the figure.

The injector 35 has an injection orifice 37.

In contrast to the state of the art, the injector 35 is arranged to pass through the front wall 23 of the flame tube 21, preferably its upstream zone 230, through which the air inlet orifices are formed. 27. In addition, this injector 35 is arranged in such a way that its injection orifice 37 opens inside the flame tube 21.

For this purpose, it will be noted that the distance D1 is sufficient to allow the passage of the fuel jet coming from the injection end 37 of the injector 35.

The operation of the injection is as follows. The fuel from the injector 35 exits through the injection port 37 and is projected against the front face 31 of the portion 260 of the injection wheel 26, where it forms a film F of fuel.

Under the action of centrifugal force, due to the rotation of the injection wheel 26, the fuel film moves towards the periphery of the wheel and passes through the lights 34, which has the effect, in contact with the air surrounding the wheel, to spray or atomize the fuel in very fine droplets G, distributed inside the flame tube 21.

The fact that the injector 31 is disposed through the front wall

23 flame tube facilitates disassembly. Preferably, its configuration will be adapted to provide for its extraction through this front wall 23.

Advantageously also, it will be noted that the injection wheel 26 has a smaller diameter than that of the state of the art shown in FIG. 1, since the bottom 22 of the flame tube 21 can be arranged closer to the In this respect, it will be noted that FIGS. 1 and 2 are not shown on the same scale.

The injection wheel 26 being of smaller diameter, its mass is lower than that of a wheel of the state of the art and its mechanical strength is also improved.

Another embodiment of the invention will now be described with reference to FIG. 3. The same elements bear the same numerical references and will not be described again in detail.

The injection wheel bears the reference 41. It is rotated by the drive shaft 30.

It differs from the injection wheel 26 in that it is full, that is to say it is not pierced with injection ports 34. Its peripheral rim 42 is flared, so as to define an annular radial face 43, preferably plane, for receiving the film F of fuel. The injector 35 is arranged so that its injection orifice 37 faces this face 43.

The axis of the injection orifice 37 forms an angle α (alpha) with the fuel receiving face 43. This angle a is advantageously between 90 ° and 180 °. When it is 180 °, the injection of fuel is tangent to the face 43.

Note also that, in this case, if we consider the median plane P of the wheel (41) perpendicular to the axis of the drive shaft 30 driving this wheel, then the axis of the injection port 37 of an injector 35 extends in a plane P1 which is both perpendicular to P and which includes the axis of the drive shaft 30. In Figure 3, the plane P1 corresponds to the plane of the sheet of the figure and in Figure 4, the plane P1 is represented by a line in dashed lines.

However, it is also possible to orient the axis of the injection orifice 37 so that it is not perpendicular to P. In other words, this axis then protrudes or deviates from the plane P1 corresponding to the plane of FIG. 3. In FIG. 4, this axis is referenced X1 -ΧΊ.

In this embodiment, it will be noted that the injector 35 is advantageously introduced less deeply into the flame tube 21 than in the embodiment of FIG. 2, since it is not necessary for its injection orifice to reach the area under the annular flange 33 of the injection wheel. It is sufficient that the injector allows the projection of fuel on the face 43. The disassembly of the injector 35 is thus facilitated.

As before, the fuel film F undergoes the centrifugal force generated by the wheel 41 and is atomized in the form of fuel droplets G.

This embodiment of the invention allows to have an injection wheel 41 which has a structure of great simplicity and good mechanical strength, since it is not pierced by through holes. Its diameter is also smaller than in the state of the art, since the bottom 22 of the flame tube 21 can be brought closer to the drive shaft 30. Finally, the combustion is located substantially on one side of the wheel. injection 41, here on the left of Figure 3.

Furthermore, it will be noted that alternative embodiments of the invention are possible. In particular, the injector 35 may be disposed through the rear wall 24 of the flame tube 21, preferably through its upstream zone 240. In this case, and when the injection wheel 26 is made according to the embodiment of FIG. 2, its annular rim 33 is turned downstream of the combustion assembly 20 and the fuel injection is done on the rear face 32 of the wheel.

When the injector is disposed through the rear wall 24 and the injection wheel 41 is in accordance with the embodiment of Figure 3, then its receiving face 43 is oriented towards the rear wall 24.

The different possible inclinations of the axis of the injection orifice 37 and the different values of the angle a described previously also apply to this variant embodiment.

Finally, according to another alternative embodiment, it is possible to provide that the flame tube 21 is made in several parts, assembled with a flange 50 which facilitates disassembly.

Claims

1. A turbomachine combustion assembly (20), comprising:

an annular flame tube (21) comprising a front wall (23) provided with an upstream zone (230) facing upstream of the combustion assembly (20), a rear wall (24) provided with a upstream zone (240) facing upstream of the combustion assembly (20) and a bottom (22) arranged opposite a driving shaft (30),

an injection wheel (26, 41) driven in rotation by said drive shaft (30) coaxial with the longitudinal axis XX 'of the combustion assembly (20), said injection wheel (26, 41) projecting partly in the flame tube (21) through its bottom (22) and being configured to spray fuel into the flame tube by centrifugation,

at least one injector (35), capable of depositing a film of fuel, on said injection wheel (26, 41),

this combustion assembly being characterized in that said injector (35) is disposed through said upstream zone (230) of the front wall (23) or through said upstream zone (240) of the rear wall (24) of the tube with flame (21) and so that its injection orifice (37) opens inside this tube (21), facing the portion (260, 43) of said injection wheel (26, 41) which is in said flame tube (21).

2. combustion assembly (20) according to claim 1, characterized in that said injector (35) is disposed through the upstream zone (230) of the front wall (23) of the flame tube (21), in that said injection wheel (26) is bent at its periphery, upstream of the combustion assembly, so as to have an annular rim (33), in that said annular flange (33) is pierced with several radial injection ports (34) and in that said injector (35) opens into the flame tube (21) facing the front face (31) of the annular peripheral portion (260) of said injection wheel which is in the flame tube (21).

Combustion unit according to claim 1, characterized in that said injector (35) is disposed through the upstream zone (240) of the rear wall (24) of the flame tube (21), in that said wheel injection nozzle (26) is bent its periphery, downstream of the combustion assembly, so as to have an annular flange (33), in that this annular flange (33) is pierced with a plurality of radial injection apertures (34) and in that said injector (35) opens into the flame tube (21) facing the rear face (32) of the annular peripheral portion (260) of said injection wheel which is in the flame tube (21).

4. Combustion assembly according to claim 1, characterized in that said injection wheel (41) is solid and has a radial annular face (43) for receiving the fuel which protrudes into the flame tube (21) and the injector (35) opens into the flame tube (21) facing this annular face (43) for receiving the fuel.

5. Combustion assembly according to claim 4, characterized in that the injector (35) is oriented to project the fuel tangentially on said face (43) for receiving fuel from the injection wheel.

Combustion unit according to Claim 4, characterized in that the fuel receiving face (43) of the injection wheel (41) forms an angle α with the axis of the injection orifice (37). of the injector (35), this angle (a) being between 90 ° and 180 °.

7. Combustion unit according to one of claims 4 to 6, characterized in that the axis of the injection orifice (37) of the injector (35) extends in a plane

(P1) which both includes the axis (30) of the injection wheel (41) and is perpendicular to the median plane (P) of the wheel (41) perpendicular to the axis of the injection wheel ( 41).

Combustion unit according to one of Claims 4 to 6, characterized in that the axis of the injection orifice (37) of the injector (35) is not perpendicular to the median plane (P). the wheel (41) perpendicular to the axis of the injection wheel (41).

9. Turbomachine comprising a combustion assembly according to one of the preceding claims.