EP2409085B1 - Turbine engine combustion chamber comprising improved primary air supply means - Google Patents

Description

TECHNICAL AREA

The present invention relates to an annular combustion chamber of a turbomachine, such as for example an airplane turbojet or turboprop.

STATE OF THE PRIOR ART

Turbomachines generally comprise an annular combustion chamber mounted downstream of a compressor.

The combustion chamber is delimited upstream by an annular bottom equipped with injection systems regularly distributed around the axis of the turbomachine and for injecting a mixture of air and fuel into the combustion chamber.

The output of the compressor opens into an enclosure in which is housed the combustion chamber. The compressor may be of axial type and have an output substantially aligned with the injection systems of the combustion chamber, or be of the centrifugal type, and comprise at the output an annular rectifier opening in a radially outer region of the enclosure of the combustion chamber.

Injection systems of the combustion chamber have peripheral bores through which air from the compressor can enter, and means for centering and guiding fuel injector heads.

The injection systems are designed to optimize the performance of the combustion chamber and thus reduce fuel consumption and pollutant emissions at the outlet of this combustion chamber.

The performance of the injection systems is, in general, even higher than the pressure drop is important inside these injection systems, and that the air supply of these systems is uniform. around their respective axes. To limit the overall pressure drop experienced by the air flow supplying the combustion chamber while allowing a high pressure drop inside the injection systems, it is therefore desirable to reduce the pressure drop as much as possible. upstream of these injection systems.

However, since the compressor outlet is axially distant from the injection systems, the air flow from the compressor generally arrives at the level of the injection systems having undergone a considerable loss of load and being distributed in a non-controlled manner. uniform around each injection system.

These problems are particularly sensitive in the case of centrifugal compressors whose output is not aligned with the injection systems of the combustion chambers but is arranged radially outwardly with respect to these injection systems.

The document EP0153842 A1 shows a turbomachine combustion chamber having combustion air collectors associated with each injection system in an annular fairing. The collectors have a shape of the circular holes formed in and by the fairing.

An annular fairing intended to cover the annular chamber bottom of a turbomachine combustion chamber is described in the document FR2910597 . Said fairing comprises openings to allow the passage of fuel injectors supported by the chamber bottom. Said openings extend to the free end of an outer fixing edge, so that the outer fixing edge is split between some of its attachment points.

STATEMENT OF THE INVENTION

The invention aims in particular to provide a simple, economical and effective solution to these problems, to avoid the aforementioned drawbacks.

In particular, it aims to reduce the pressure drop of the air flow coming from a compressor in a turbomachine, between the output of this compressor and the inlet of injection systems of a combustion chamber of the turbomachine , in particular to allow an increase in the pressure drop inside these injection systems without considerably increasing the overall pressure drop of the air flow supplying the combustion chamber.

The invention also aims to improve the uniformity of the air supply combustion chamber injection systems.

To this end, the invention proposes an annular combustion chamber intended to equip a turbomachine, comprising a chamber bottom arranged at the upstream end of the combustion chamber, as well as a plurality of air injection and air injection systems. fuel distributed circumferentially around an axis of the combustion chamber and mounted on the chamber bottom. The annular combustion chamber further comprises, associated with each injection system, an air manifold comprising two walls mounted on the chamber bottom and projecting upstream to form an obstacle to a circumferential flow of air around the chamber. the axis of the combustion chamber, and an air inlet opening formed at the upstream end of the aforementioned air collector. According to the invention, the air intake opening of each air collector is open radially outwards with respect to an axis of the corresponding injection system.

The air collectors according to the invention can optimally channel a flow of air from a radially outer region relative to the respective axes of the injection systems and feeding these injection systems, around each of these systems.

Air collectors thus make it possible to reduce the pressure drop experienced by this flow of air upstream of these injection systems, and to make the air supply of these systems more uniform.

This results in an improvement in the general performance of the combustion chamber, and more particularly an increase in its efficiency and a reduction of emissions of pollutants by the combustion chamber.

An air flow coming from a region radially external to the respective axes of the injection systems of the combustion chamber is encountered in particular in turbomachines comprising a centrifugal compressor. The invention is therefore particularly advantageous when applied to a turbomachine of this type.

Preferably, when the air intake opening of each collector is viewed in projection in a transverse plane perpendicular to a tangential plane passing through the axis of the corresponding injection system, the portion of said opening which is located radially outwardly with respect to the aforesaid tangential plane has an opening area greater than that of the part of said opening which is located radially inward with respect to this tangential plane.

This configuration further optimizes the intake of air from a radially outer region relative to the respective axes of the injection systems of the combustion chamber.

Each air manifold comprises two walls which are mounted on the chamber bottom, project upstream, and are arranged on either side of the corresponding injection system, these walls forming an obstacle to a circumferential flow of air around the axis of the combustion chamber.

In a first embodiment of demonstrative example, the two walls of each air collector have a concavity turned towards said air collector and are connected to one another by two opposite ends of each of these walls, so that each air manifold has a generally tubular shape and has an upstream end forming said air inlet opening.

This makes the distribution of air around each injection system more uniform.

Advantageously, the upstream end of each air manifold is shaped so that a radially inner portion of the upstream end is offset upstream relative to a radially outer portion of said upstream end of the air collector.

According to the invention, the combustion chamber comprises an annular fairing of chamber bottom arranged upstream of the chamber bottom and to which the walls of each air manifold are connected substantially sealingly on either side of an orifice corresponding formed in the shroud and forming said air intake opening of the air collector.

The aforementioned walls allow to delimit compartments forming air collectors between the chamber bottom and the fairing, around each injection system.

Said walls of each air collector extend radially and each of these walls is part of two consecutive air collectors around the axis of the combustion chamber.

This configuration has the particular advantage of minimizing the total number of air collector walls.

The air inlet opening of each air manifold preferably has a flared shape radially outwardly.

Alternatively, or in a complementary manner, the annular fairing may comprise a radially inner annular portion and a radially outer annular portion between which said air intake openings are formed, the radially inner annular portion being offset upstream relative to at the radially outer annular portion.

In this case, the shape of the fairing makes it possible to orient the air intake opening radially outwards.

In a general manner, each injection system comprising an injector head centering and guiding sleeve, each air collector preferably comprises at least one part extending upstream beyond an upstream end of said bushing of the corresponding injection system.

The air collectors and have optimal abilities to channel air admitted into the injection systems that equip the combustion chamber.

The invention also relates to a turbomachine comprising a combustion chamber of the type described above.

BRIEF DESCRIPTION OF THE DRAWINGS

• la figure 1 est une vue schématique partielle en perspective d'une turbomachine selon un exemple démonstratif ;
• la figure la est une vue schématique partielle de la turbomachine de la figure 1 en projection dans le plan P1 de la figure 1 ;
• la figure 2 est une vue schématique partielle en coupe axiale et à plus grande échelle de la turbomachine de la figure 1 ;
• la figure 3 est une vue semblable à la figure 1, d'une turbomachine selon l'invention ;
• la figure 3a est une vue schématique partielle de la turbomachine de la figure 3 en projection dans le plan P1 de la figure 3 ;
• la figure 4 est une vue semblable à la figure 3a, illustrant une variante de réalisation de la turbomachine de la figure 3.

The invention will be better understood, and other details, advantages and characteristics thereof will appear on reading the description. following example by way of non-limiting example and with reference to the accompanying drawings in which:

• the figure 1 is a partial schematic perspective view of a turbomachine according to a demonstrative example;
• FIG. 1a is a partial schematic view of the turbomachine of the figure 1 in projection in the plane P1 of the figure 1 ;
• the figure 2 is a partial schematic view in axial section and on a larger scale of the turbomachine of the figure 1 ;
• the figure 3 is a view similar to the figure 1 , a turbomachine according to the invention;
• the figure 3a is a partial schematic view of the turbomachine of the figure 3 in projection in the plane P1 of the figure 3 ;
• the figure 4 is a view similar to the figure 3a , illustrating an embodiment variant of the turbomachine of the figure 3 .

DETAILED PRESENTATION

The Figures 1 to 2 represent a combustion chamber 10 of a turbomachine according to a demonstrative example as well as the immediate environment of this combustion chamber.

In a known manner, the combustion chamber 10 is housed in an enclosure 12 which is arranged downstream of a compressor of the turbomachine, of the centrifugal type, the output of which is connected to a radial diffuser 14, itself connected at the output to a flow rectifier 16 which opens into a radially outer region of the enclosure 12.

The combustion chamber 10 is delimited by two substantially cylindrical coaxial walls 18 and 20, respectively internal and external, and by an annular chamber bottom 22 which extends substantially radially at the upstream end of the chamber 10 and which is connected by its radial ends to both walls 18 and 20.

The inner 18 and outer 20 walls of the combustion chamber 10 are attached downstream by two inner and outer ferrules 24 and 26 respectively on a substantially cylindrical inner wall 28 connected to the diffuser 14, and on an outer casing 30, so as to delimit the enclosure 12.

Injection systems 32, which are regularly distributed around the axis 34 of the combustion chamber, are mounted in the chamber bottom 22. Each injection system 32 comprises in particular a centering and guiding bushing 36. a head 38 of a fuel injector 40, and air inlet ports 42 arranged around an axis 44 of the injection system.

The bushing 36 of each injection system 32 aligns the corresponding injector head 38 on the axis 44 of the injection system. In addition, the injection systems 32 are configured to allow a certain radial and axial displacement of the injector heads 38, to take account of any differential expansions likely to cause relative displacements between the injectors 40 and the combustion chamber 10.

In operation, a stream of air 46 coming from the centrifugal compressor is injected by the rectifier 16 into the enclosure 12.

The air flow 46, which arrives in a radially outer region of the enclosure 12, separates into three parts in this chamber 12.

A first portion 48 of the air flow flows downstream along the outer wall 20 of the combustion chamber 10, and partially enters the combustion chamber 10 through orifices 50 formed in its outer wall 20.

A second portion 52 of the air flow flows downstream along the internal wall 18 of the combustion chamber 10, and partially enters the combustion chamber 10 through orifices 54 formed in its inner wall 18.

Finally, a third portion 56 of the air flow feeds the injection systems 32 of the combustion chamber 10.

In accordance with the illustrative example, the combustion chamber 10 is equipped with a plurality of air collectors 58 (one of which is visible on the Figures 1 to 2 ).

Each air manifold 58 comprises two similar walls 60 and 62 ( figure 1 ) which are curved around the injection system 32 corresponding by having a concavity facing the injection system 32, and which are mounted on the chamber bottom 22 at their respective downstream ends.

In the demonstrative example, the two walls 60 and 62 of each air collector 58 each comprise two opposite end edges, respectively 60a, 60b and 62a, 62b, through which these two walls 60 and 62 are connected to each other. the other, so that each air manifold 58 has a generally tubular shape.

The air manifolds 58 each have an upstream end edge defining an air inlet opening 64, through which air 56 from the rectifier 16 can penetrate to reach the air inlet ports 42 of the injection systems 32.

The two walls 60, 62 of each air collector 58 are truncated upstream along a plane inclined relative to the axis 44 of the corresponding injection system so that the air intake opening 64 of each collector air 58 is open towards the outlet of the rectifier 16, that is to say open radially outwardly relative to the axis 44 of the aforementioned injection system, to facilitate the entry of air from this rectifier 16 in the air collectors 58.

The upstream end edge of each air manifold 58 thus has a radially inner portion 66 which is offset upstream with respect to a radially outer portion 68 of the upstream edge.

As shown in figure 1a when each air inlet opening 64 is viewed in projection in the transverse plane P1 of the figure 1 , which is perpendicular to the tangential plane P2 passing through the axis 44 of the injection system 32, the portion of the opening 64 which is located radially outwardly relative to the aforementioned tangential plane P2 has an opening surface S ₁ greater than that S ₂ of the portion of said opening 64 which is located radially inward with respect to the tangential plane P2.

As shown in figure 2 , the radially inner portion 66 of the upstream edge of each air manifold 58 extends upstream beyond the upstream end of the bushing 36 for centering and guiding the corresponding injector head 38. This radially inner portion 66 thus forms a scoop which is particularly effective for guiding the flow of air 56 coming from the rectifier 16.

The inclination of the air intake opening 64 of each air manifold 58 with respect to the axis 44 of the corresponding injection system is notably defined so as not to hinder axial and radial displacements of the injector head 38 corresponding in operation and also during assembly and disassembly of the injector 40.

Thus, the air intake opening 64 forms with the axis 44 an angle α ( figure 2 ) which is typically between about 40 degrees and 80 degrees.

In the demonstrative example shown on the Figures 1 to 2 , the two walls 60 and 62 of each air manifold 58 are fixed at their downstream end to an annular piece 70, sometimes called a cup stopper, which is integral with the chamber bottom 22, and which comprises an annular flange 72 extending radially about the axis 44 of the corresponding injection system 32, and an annular flange 74 which extends parallel to the 44 axis from the inner periphery of the annular flange 72 of the stop cup 70.

Fixing the walls 60 and 62 on the stop cup 70 is for example made by welding and so that the walls 60 and 62 extend in the extension of the annular rim 74 of the stop cup 70.

In a manner known per se, the stop cup 70 makes it possible to axially block the injection system 32 by cooperation of the annular flange 72 of the stop cup with an annular flange 76 secured to the injection system 32 and mounted sliding radially in an annular groove formed between the chamber bottom 22 and the flange 72 of the stop cup 70.

In general, the air collectors 58 make it possible to channel the air coming from the straightener 16 around each injection system 32, which makes it possible to reduce the pressure losses upstream of these injection systems improve the uniformity of the air supply of these injection systems. For this purpose, the air collectors 58 have a remarkable property in that they each form an obstacle to the flow of air circumferentially between two neighboring injection systems, along the chamber bottom 22.

The figure 3 represents an embodiment of the invention in which the bottom 22 of the combustion chamber 10 is equipped with an annular protective fairing 78 arranged upstream of the chamber bottom 22.

The shroud 78 has a radially inner continuous annular portion 80 which has an edge 82 fastened together on an inner rim 84 of the chamber bottom 22 and on an upstream edge 86 of the inner wall 18 of the combustion chamber 10.

The fairing 78 further comprises air intake openings 88 which are arranged opposite each injection system 32 and which extend outwards as far as the radially outer end of the fairing 78 so that the latter has a radially outer edge 90 split at each of these openings 88. This outer edge 90 of the shroud is fixed jointly on an outer rim 92 of the chamber bottom 22 and on an upstream edge 94 of the outer wall 20 of the combustion chamber 10.

As shown in figure 3a when each air inlet opening 88 is seen in projection in the transverse plane P1 perpendicular to the tangential plane P2 passing through the axis 44 of the injection system 32, the portion of the opening 88 which is situated radially at the outside relative to the aforementioned tangential plane P2 has an opening surface S ₁ greater than that S ₂ of the portion of the opening 88 which is located radially inward with respect to the tangential plane P2.

The air intake openings 88 are thus open radially outwardly relative to the axis 44 of each injection system 32, which facilitates the flow of the air stream 56 from the rectifier 16 and feeding injection systems 32.

In the example shown on the figure 3 , the air intake openings 88 of the shroud 78 have a flared shape radially outwardly.

Alternatively, each air inlet opening 88 may have a shape centered on an axis 95 contained in a plane passing through the axis 44 of the corresponding injection system and by the axis 34 of the combustion chamber, and which is offset radially outwardly with respect to said axis 44 of the injection system or inclined with respect to this axis 44. figure 4 illustrates an opening 88 of this type seen in projection in the aforementioned transverse plane P1.

In any case, the air intake openings 88 verify the property above relative to the opening surfaces S ₁ and S ₂ defined on either side of the tangential plane P2.

In addition, it should be noted that each air intake opening 88 extends between a radially outer portion 102 of the fairing and the radially inner annular portion 80 of said fairing 78, which radially inner portion 80 is shifted towards the outside. upstream relative to the radially outer portion 102 above.

Furthermore, in the embodiment of the invention, the bottom 22 of the combustion chamber 10 is equipped with pairs of collector walls 96 and 98 arranged on either side of each injection system 32 and on the other side. corresponding aperture 88, as shown in FIG. figure 3 . These collector walls 96, 98 are flat and project upstream from the chamber bottom 22 extending in respective substantially radial planes with respect to the axis 34 of the combustion chamber.

Each collector wall 96, 98 is substantially sealingly connected to the chamber bottom 22 and to the fairing 78, for example by welding or bolting.

In this way, each pair of walls 96 and 98 delimits a compartment between the chamber bottom 22 and the fairing 78. This compartment forms an air manifold 100 which is functionally similar to air to the air manifold 58 as a demonstrative example. . This air collector 100 allows in particular to channel the air around each injection system 32 by prohibiting any flow circumferential air between two neighboring injection systems along the chamber bottom 22.

Only one wall 96, 98 of the air collector 100 is provided between two adjacent injection systems 32, so that each wall 96, 98 of the air collector 100 participates in the formation of two collectors. 100 neighbors.

Claims (6)

1. Annular combustion chamber (10) to be fitted on a turbomachine and comprising a chamber end wall (22) arranged at the upstream end of the combustion chamber (10), an annular chamber end wall shielding (78) arranged on the upstream side of the chamber end wall (22), and a plurality of air and fuel injection systems (32) circumferentially distributed around an axis (34) of the combustion chamber (10) and mounted on said chamber end wall (22), said combustion chamber (10) also comprising an air manifold (100) associated with each injection system (32), said air manifold comprising two walls (96, 98) mounted on the chamber end wall (22) and projecting in the upstream direction on each side of the corresponding injection system (32) to form an obstacle to a circumferential airflow around the axis (34) of the combustion chamber (10), said walls (96, 98) being connected in an almost airtight manner to the annular shielding chamber end wall (78) on each side of a corresponding orifice formed in said annular chamber end wall shielding (78), said orifice forming an air inlet opening (88) at the upstream end of said air manifold (100) and said orifice opening radially outwards from an axis (44) of said injection system, said combustion chamber (10) being characterized in that said walls (96, 98) extend radially, and in that each of these walls (96, 98) forms part of two consecutive air manifolds (100).
2. Annular combustion chamber according to claim 1, characterised in that when said air inlet opening (88) of each air manifold (100) is seen in projection in a transverse plane (P1) perpendicular to a tangential plane (P2) passing through said centre line (44) of the corresponding injection system (32), the part of said opening (88) located radially outwards from said tangential plane (P2) has a larger opening area than the part of said opening (88) that is located radially inwards from said tangential plane (P2).
3. Annular combustion chamber according to claim 1 or 2, characterised in that said air inlet opening (88) of each air manifold (100) is tapered radially outwards.
4. Annular combustion chamber according to any one of claims 1 to 3, characterised in that said annular shielding (78) comprises a radially inward annular part (80) and a radially outward annular part (102) between which said air inlet openings (88) are formed, said radially inward annular part (80) being offset from the radially outward annular part (102) in the upstream direction.
5. Annular combustion chamber according to any one of the previous claims, characterised in that each injection system (32) comprises a centring and guide bushing (36) for the injector head, and each air manifold (100) comprises at least one part that extends in the upstream direction beyond an upstream end of said bushing (36) of the corresponding injection system (32).
6. Turbomachine, characterised in that it comprises a combustion chamber (10) according to any one of the previous claims.

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