Injection system for a combustion chamber of a turbine engine having optimised purge holes
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- SAFRAN AIRCRAFT ENGINES SAS
- Filing Date
- 2024-06-20
- Publication Date
- 2026-04-29
AI Technical Summary
The existing injection systems in turbomachines face challenges in maintaining ignition performance and combustion stability, particularly during difficult ignition conditions, due to the influence of purge holes which can lead to flame stagnation and coking risks.
The injection system features purge holes with a curved shape and inclined orientations, optimizing their design to co-rotate with the air intake swirl, maximizing air pressure ingestion and minimizing pressure losses, thereby reducing the impact on ignition performance while maintaining protection against coking and flame rise.
This optimized design enhances ignition stability and performance by maximizing air pressure utilization and minimizing pressure losses, ensuring reliable combustion chamber operation even under difficult conditions.
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Abstract
Description
[0001] Description
[0002] Title: Injection system for turbomachine combustion chamber with optimized purge holes
[0003] Technical field
[0004] The present invention relates to the field of injection systems intended for the injection of air and fuel mixtures into the combustion chambers of turbomachines, in particular turbojets intended for the propulsion of aircraft.
[0005] State of the prior art
[0006] A turbomachine, such as a turbojet, comprises one or more compressor(s) delivering pressurized air to a combustion chamber where the air mixed with fuel is ignited to generate hot combustion gases. These gases flow downstream of the chamber to one or more turbine(s) which transform(s) the energy thus received to drive the compressor(s) in rotation and provide the work necessary, for example, to propel an aircraft. Typically, an annular combustion chamber comprises an inner annular wall and an outer annular wall, connected together at their upstream end by an annular chamber end wall. The chamber end wall has, circumferentially spaced apart, a plurality of passages each receiving an injection system in the middle of which is positioned a fuel injector nozzle, the assembly allowing the supply of a mixture of air and fuel into the combustion chamber.
[0007] The fuel, initially in liquid form, is brought to the chamber by each injector, the nozzle of which causes the fuel to be sprayed into fine droplets. The process of spraying and then evaporating the fuel is initiated at the nozzle of the injector and continues within the injection system, in particular at a convergent-divergent internal wall, or venturi, and a divergent outlet wall, or bowl, by a driving effect of the pressurized air coming from the compressor. This pressurized air passes through, on the one hand, one or more swirlers of the injection system, for example of the radial or axial-radial type, to set the fuel sprayed by the injector into rotation, and, on the other hand, orifices provided in different parts of the injection system.
[0008] Such orifices, called purge holes, are sometimes formed in a wall defining, on an upstream side, an upstream external surface of the injection system, and delimiting, on a downstream side, such a swirler. Such purge holes are provided to avoid or limit the risks of flame rising within the swirler and the risks of coking along the walls delimiting the swirler.
[0009] The presence or absence of such purge holes on a given injection system, and, where applicable, the sizing of the purge holes, are key parameters for sizing the re-ignition ceiling of a combustion chamber. The choice of the dimensions of such purge holes also appears to be a compromise between re-ignition performance and combustion stability on the one hand, and a risk of fuel stagnation in the injection systems on the other hand.
[0010] Under difficult ignition conditions such as in-flight re-ignition conditions, it may happen that the flame kernel initiated in front of the spark plug struggles to reach the recirculation region defined at the outlet of an injection system relatively close to the spark plug. It may also happen that the flame stagnates in front of such an injection system without propagating to the neighboring injection systems, leading to a failure of combustion chamber ignition and requiring a new ignition attempt.
[0011] Statement of the invention
[0012] The present invention aims to optimize the purge holes in order to reduce their influence on ignition performance, particularly in difficult conditions.
[0013] The invention proposes for this purpose an injection system for injecting a mixture of air and fuel into a turbomachine combustion chamber, comprising a sleeve for receiving a fuel injector nozzle, a bowl, and at least one air intake swirler arranged axially between the sleeve and the bowl for injecting air into the injection system having a rotating movement in a circumferential swirler direction, around an injection axis of the injection system.
[0014] The sleeve comprises a downstream end wall defining, on an upstream side of the injection system, an upstream external surface of the latter, and on an opposite side, an upstream internal surface delimiting said air intake swirler upstream.
[0015] The downstream end wall comprises purge holes each having an inlet opening through said upstream external surface and an outlet opening through said upstream internal surface.
[0016] The inlet has an inlet axis oriented along an inlet direction, and the outlet has an outlet axis oriented along an outlet direction.
[0017] In addition, at least the outlet direction has a circumferential inclination, defined by reference to a cylindrical coordinate system centered on the injection axis, and in the same direction as the circumferential twist direction.
[0018] The purge holes are thus configured for co-rotating air injection with the air from the air intake swirler adjacent to the downstream end wall of the sleeve. The impact of the air from the purge holes on the swirl flow from the aforementioned swirler is thus reduced. In this way, the purge function, i.e. protection against coking and flame rise, can be maintained without this being to the detriment of the flame stability and the ignition performance of the combustion chamber.
[0019] It should be noted that, because the air intake swirler is delimited upstream by the downstream end wall of the sleeve, this swirler is not of a purely axial type but can be of a radial type or of an axia l-radia I type, that is to say that the swirler has a pure radial orientation or with an inclination in the downstream direction.
[0020] In embodiments, the outlet direction has a radial inclination toward the injection axis.
[0021] In other embodiments, the output direction is orthogonal to the radial direction of said cylindrical coordinate system.
[0022] Furthermore, according to the invention, each purge hole is of curved shape, so that the inlet direction has a circumferential inclination, defined with reference to said cylindrical coordinate system, less than the circumferential inclination of the outlet direction, for each purge hole.
[0023] Such a geometric property of the purge holes makes it possible to maximize the pressure of the air ingested by the purge holes by taking full advantage of the dynamic pressure of the air flow which circulates downstream and feeds the purge holes, and to minimize the pressure losses as a corollary.
[0024] In some embodiments, the circumferential tilt of the input direction may be zero.
[0025] In addition, the inlet direction may have a radial inclination, defined by reference to said cylindrical coordinate system, less than or equal to the radial inclination of the outlet direction, for each purge hole.
[0026] Alternatively, the radial inclination of the input direction may be zero.
[0027] The invention also relates to a turbomachine for an aircraft, comprising a combustion chamber and at least one injection system of the type defined above for supplying the combustion chamber with a mixture of air and fuel.
[0028] Brief description of the drawings
[0029] The invention will be better understood, and other details, advantages and characteristics thereof will appear on reading the following description given by way of non-limiting example and with reference to the appended drawings in which:
[0030] [Fig. 1] is a schematic axial sectional view of a turbomachine intended for aircraft propulsion;
[0031] [Fig. 2] is a schematic half-view in axial section of a combustion chamber within the turbomachine of Figure 1;
[0032] [Fig. 3] is a schematic axial sectional view of an injection system of a known type, suitable for equipping the combustion chamber of Figure 2;
[0033] [Fig. 3A] is an enlarged schematic view of a portion of Figure 3;
[0034] [Fig. 4] is a schematic perspective view, substantially from upstream, of an injection system according to a first example not covered by the invention, also suitable for equipping the combustion chamber of Figure 2; [Fig. 5] is a schematic perspective view, substantially from downstream, of an upstream part of the injection system of Figure 4;
[0035] [Fig. 6] is a schematic perspective view of an inlet section of a purge hole belonging to the injection system of Figure 4;
[0036] [Fig. 6A] is a view of the inlet section of the drain hole in projection in a plane (R'C');
[0037] [Fig. 6B] is a view of the inlet section of the drain hole in projection in a plane (R'X');
[0038] [Fig. 6C] is a view of the inlet section of the drain hole projected onto a plane (X'C');
[0039] [Fig. 7] is a schematic perspective view of an outlet section of the purge hole;
[0040] [Fig. 7A] is a view of the outlet section of the drain hole in projection in a plane (R'C');
[0041] [Fig. 7B] is a view of the outlet section of the drain hole in projection in a plane (R'X');
[0042] [Fig. 7C] is a view of the outlet section of the drain hole in projection in a plane (X'C');
[0043] [Fig. 8] is a view similar to Figure 4, of an injection system according to a second example not covered by the invention, also suitable for equipping the combustion chamber of Figure 2;
[0044] [Fig. 9] is a view similar to Fig. 5, of the injection system of Fig. 8;
[0045] [Fig. 10] is a schematic perspective view of an inlet section of a purge hole belonging to the injection system of Figure 8;
[0046] [Fig. 10A] is a view of the inlet section of the drain hole in projection in a plane (R'C');
[0047] [Fig. 10B] is a view of the inlet section of the drain hole projected onto a plane (R'X');
[0048] [Fig. 10C] is a view of the inlet section of the drain hole projected onto a plane (X'C');
[0049] [Fig. 11] is a schematic perspective view of an outlet section of the purge hole; [Fig. 11A] is a view of the outlet section of the purge hole in projection in a plane (R'C');
[0050] [Fig. 11B] is a view of the outlet section of the drain hole in projection in a plane (R'X');
[0051] [Fig. 11C] is a view of the outlet section of the drain hole in projection in a plane (X'C');
[0052] [Fig. 12] is a view similar to Figure 4, of an injection system according to an embodiment of the invention, also suitable for equipping the combustion chamber of Figure 2;
[0053] [Fig. 13] is a view similar to Fig. 5, of the injection system of Fig. 12;
[0054] [Fig. 14] is a schematic perspective view of an inlet section of a purge hole of a variant of the injection system of Fig. 12;
[0055] [Fig. 14A] is a view of the inlet section of the drain hole in projection in a plane (R'C');
[0056] [Fig. 14B] is a view of the inlet section of the drain hole in projection in a plane (R'X');
[0057] [Fig. 14C] is a view of the inlet section of the drain hole projected onto a plane (X'C');
[0058] [Fig. 15] is a schematic perspective view of an outlet section of the purge hole; [Fig. 15A] is a view of the outlet section of the purge hole in projection in a plane (R'C');
[0059] [Fig. 15B] is a view of the outlet section of the drain hole in projection in a plane (R'X');
[0060] [Fig. 15C] is a view of the outlet section of the drain hole in projection in a plane (X'C').
[0061] Throughout these figures, like references may designate like or similar elements. Detailed description of preferred embodiments
[0062] Figure 1 illustrates a turbomachine 10, for example a twin-spool, dual-flow turbojet for aircraft, generally comprising a fan 12 intended for the suction of an air flow Fl dividing downstream of the fan into a primary flow F2 circulating in a primary flow channel, hereinafter referred to as the primary vein PV, and a secondary flow F3 circulating in a secondary flow channel, hereinafter referred to as the secondary vein SV, arranged around the primary vein PV.
[0063] By way of illustration, the turbomachine generally comprises a low-pressure compressor 14, a high-pressure compressor 16, a combustion chamber 18, a high-pressure turbine 20 and a low-pressure turbine 22 which jointly define the primary stream PV. The respective rotors of the high-pressure compressor and the high-pressure turbine are connected by a shaft called the “high-pressure shaft”, while the respective rotors of the low-pressure compressor and the low-pressure turbine are connected by a shaft called the “low-pressure shaft”, in a well-known manner. These rotors are rotatably mounted around an axis 28 of the turbomachine.
[0064] Throughout this description, the axial direction X is the direction of the axis 28. We also consider a first cylindrical coordinate system centered on the axis 28, in which a radial direction R is at all points orthogonal to the axis 28 and passes through the latter, while an ortho-radial or circumferential direction C is at all points orthogonal to the radial direction R and to the axis 28. A transverse plane is a plane orthogonal to the axis 28. The terms "internal" and "external" refer respectively to a relative proximity, and a relative distance, of an element with respect to the axis 28. Finally, the "upstream" and "downstream" directions are defined with reference to the general direction FD of the flow of gases in the primary PV and secondary SV veins of the turbomachine, in the axial direction X.
[0065] Figure 2 illustrates the combustion chamber 18 and its immediate environment, in a known configuration. Conventionally, this combustion chamber, which is of the annular type, comprises two coaxial annular walls, respectively radially internal 32 and radially external 34, which extend from upstream to downstream, in the aforementioned direction FD, around the axis of the combustion chamber which merges with the longitudinal axis 28 of the turbomachine. These radially internal 32 and radially external 34 annular walls are connected to each other at their upstream end by an annular chamber bottom wall 40, so that these walls externally delimit an interior volume V of the combustion chamber 18.
[0066] The annular chamber bottom wall 40 comprises passages distributed around the longitudinal axis 28 and through which are respectively mounted injection systems 42 configured to each deliver a layer of a mixture of air and fuel centered along a respective injection axis 44.
[0067] In addition, the combustion chamber is generally equipped with one or more spark plugs 45 mounted through the outer annular wall 34.
[0068] In operation, a portion 46 of an air flow 48 coming from a compressor such as the high-pressure compressor 16 supplies the injection systems 42 while another portion 50 of this air flow bypasses the combustion chamber by flowing downstream along the coaxial walls 32 and 34 of this chamber and allows, in certain cases, the supply of air inlet orifices provided within these walls 32 and 34.
[0069] As shown in Figure 3, each injection system 42 generally comprises, from upstream to downstream, a sleeve 52, sometimes called a “sliding feedthrough”, intended to receive a fuel injector nozzle 54 (visible in Figure 2 but not in Figure 3), as well as one or more air intake swirlers 56, 58 (sometimes called “swirlers”), possibly separated from each other by a wall 59 with a radially internal end of convergent-divergent shape, commonly called a “venturi”, for injecting air into the injection system having a gyratory movement in a circumferential swirl direction SCI around the injection axis 44, and finally a bowl 60, sometimes called a “mixing bowl”, which essentially takes the form of a wall of revolution having a shape which diverges downstream. These elements are centered relative to the injection axis 44.
[0070] The present description refers to a second cylindrical coordinate system in which an axial direction X' is parallel to the injection axis 44 of an injection system considered, a radial direction R' is at all points orthogonal to the injection axis 44 and passes through the latter, while an orthoradial or circumferential direction C' is at all points orthogonal to the radial direction R' and to the injection axis 44. In this context, a transverse plane is a plane orthogonal to the injection axis 44, and the terms "internal" and "external" respectively refer to a relative proximity, and a relative distance, of an element with respect to the injection axis 44.
[0071] Each of the swirlers 56, 58 comprises, in a well-known manner, fins 56A, 58A which delimit between them air channels, with respective axes oriented in directions each having a radial component and a circumferential component so as to give a swirling character to the air flow passing through the swirler.
[0072] The injection system illustrated in Figure 3 comprises two successive swirlers 56 and 58, both of the radial type, i.e. oriented transversely to the injection axis 44. In other words, the respective axes of the air channels defined between the fins of such swirlers are included in a plane transverse to the injection axis 44. The present disclosure is however also applicable to injection systems comprising one or more swirlers of the axia l-radia I type, i.e. in which the respective axes of the air channels extend in respective directions having an axial component and a radial component. Injection systems comprising both an axial-radial type swirler and a radial type swirler are also possible, as are injection systems comprising only a single radial or axial-radial type swirler.
[0073] In a manner known per se, the sleeve 52 comprises a downstream end wall 62 defining, on an upstream side of the injection system, an upstream external surface 62A of the latter, and on an opposite side, an upstream internal surface 62B delimiting upstream the air intake swirler 56 (at least a radially internal portion thereof). In addition, the downstream end wall 62 of the sleeve comprises purge holes 64 each having an inlet 64A opening through the upstream external surface 62A and an outlet 64B opening through the upstream internal surface 62B. Such purge holes 64 are provided, in a known manner, to avoid or limit the risks of flame rising within the swirler 56 and the risks of coking along the walls delimiting the swirler.
[0074] As explained above, the present invention aims to optimize the purge holes in order to reduce the influence of the latter on the ignition performance, particularly in difficult conditions.
[0075] To describe such a drain hole 64, the present description refers to an inlet axis A1 of the drain hole as being an axis passing through a center CA of the inlet 64A of the drain hole, and having as its direction a direction tangent to the inner surface of the drain hole at the inlet 64A, averaged over the circumference of the inlet 64A. Similarly, an outlet axis A2 of the drain hole is an axis passing through a center CB of the outlet 64B of the drain hole, and having as its direction a direction tangent to the inner surface of the drain hole at the outlet 64B, averaged over the circumference of the outlet 64B. Furthermore, for the purposes of the present description, the inlet direction DI of such a drain hole is a Euclidean vector oriented from upstream to downstream having as its direction the direction of the inlet axis A1 of the drain hole and having an arbitrarily chosen norm.Similarly, the outlet direction D2 of such a purge hole is a Euclidean vector oriented from upstream to downstream having as its direction the direction of the outlet axis A2 of the purge hole and having an arbitrarily chosen norm.
[0076] In general, the axial, circumferential and radial components of the inlet direction DI are defined by reference to the second cylindrical coordinate system taken at the center CA of the inlet 64A of a purge hole considered. Similarly, the axial, circumferential and radial components of the outlet direction D2 are defined by reference to the second cylindrical coordinate system, taken at the center CB of the outlet 64B of the purge hole considered.
[0077] In addition, the possible circumferential inclination of the inlet direction DI is the angle 0 or 01 between the axial direction X', defined at the center CA of the inlet 64A of the considered purge hole, and the orthogonal projection of the inlet direction DI in a local plane (X',C') passing through the center CA, as illustrated in Figures 6 and 6C, 10 and 10C, 14 and 14C. Similarly, the circumferential inclination of the outlet direction D2 is the angle 0 or 02 between the axial direction X', defined at the center CB of the outlet 64B of the considered purge hole, and the orthogonal projection of the outlet direction D2 in a local plane (X',C') passing through the center CB, as illustrated in Figures 7 and 7C, 11 and 11C, 15 and 15C. A circumferential inclination 0 between 0 and 90 degrees thus results in a circumferentially inclined direction in the same direction as the circumferential direction of SCI twist.
[0078] Finally, the possible radial inclination of the inlet direction DI is the angle P or pi between the axial direction X', defined at the center CA of the inlet 64A of the purge hole considered, and the orthogonal projection of the inlet direction DI in a local plane (R',X') passing through the center CA, as illustrated in Figures 10 and 10B, 14 and 14B. Similarly, the possible radial inclination of the outlet direction D2 is the angle P or P2 between the axial direction X', defined at the center CB of the outlet 64B of the purge hole considered, and the orthogonal projection of the outlet direction D2 in a local plane (R',X') passing through the center CB, as illustrated in Figures 11 and 11B, 15 and 15B. A radial inclination P between 0 and 90 degrees thus results in an orientation inclined radially inwards, that is to say in the direction of the injection axis 44.
[0079] In the prior art corresponding to the injection system visible in FIG. 3, such purge holes 64 are oriented purely axially in the second cylindrical coordinate system. Such purge holes known from the prior art are thus of cylindrical shape and have inlet axes A1 and outlet axes A2 which are coincident, parallel to the injection axis 44.
[0080] The invention provides, in general, that at least the outlet direction D2 of the purge holes 64 has a circumferential inclination in the same direction as the circumferential swirl direction SCI. The purge holes 64 are thus configured for co-rotating air injection with the air from the air intake swirl 56 adjacent to the downstream end wall 62 of the sleeve 52. The purge holes thus contribute to the “swirl number” within the injection system, the “swirl number” being, as a person skilled in the art knows, a parameter representative of the ratio of the quantities of movement of the air, respectively in the circumferential direction C', and in the direction X' of the injection axis 44. The reduction in the swirl number due to the air from the purge holes 64 is thus limited.In this way, the purge function, i.e. protection against coking and flame rise, can be achieved without compromising flame stability and combustion chamber ignition performance.
[0081] Of course, the purge holes 64 being defined through the downstream end wall 62, their inlet DI and outlet D2 directions necessarily have a non-zero axial component.
[0082] Elements common to the invention will first be described with reference to two examples not covered by the invention described with reference to FIGS. 4 to 11C, in which the purge holes 64 are each of cylindrical shape, whereby the inlet axis A1 and the outlet axis A2 of each purge hole are coincident. The same is obviously true with regard to the inlet directions D1 and outlet directions D2.
[0083] More precisely, in the first example (Figures 4 to 7C), the output direction D2 has a zero radial component.
[0084] The circumferential inclination 0 of the outlet direction D2 is preferably between 5 and 80 degrees. In other words, the ratio between the tangential component and the axial component of the outlet direction D2 is preferably between 0.1 and 6. In preferred embodiments, the circumferential inclination 0 of the outlet direction D2 is between 5 and 60 degrees.
[0085] The second example (Figures 8 to 11C) differs from the first example in that the outlet direction D2 has a negative (non-zero) radial component, whereby the purge holes 64 are inclined radially inwardly in the downstream direction.
[0086] The radial inclination P of the output direction D2 is preferably less than 80 degrees. In other words, the ratio between the radial component and the axial component of the output direction D2 is preferably less than 6.
[0087] In this second example, the circumferential inclination of the outlet direction D2 is preferably still between 5 and 80 degrees, for example between 5 and 60 degrees. As in the first example, the ratio between the tangential component and the axial component of the outlet direction D2 is thus also between 0.1 and 6.
[0088] Finally, according to the invention (figures 12 to 15C), each purge hole 64 is of curved shape, so that the circumferential component of the inlet direction DI has an absolute value lower than the absolute value of the circumferential component of the outlet direction D2, for each purge hole 64. In other words, the inlet axis A1 is less inclined in the circumferential direction than the outlet axis A2, and the circumferential inclination 01 of the inlet direction DI is thus less than the circumferential inclination 02 of the outlet direction D2.
[0089] Such a geometric property of the purge holes 64 makes it possible to maximize the pressure of the air ingested by the purge holes by making the best use of the dynamic pressure of the air flow which circulates downstream and feeds the purge holes, and to minimize the pressure losses as a corollary.
[0090] Thus, in the example illustrated by figures 12 and 13, the circumferential inclination of the entry direction DI is zero.
[0091] In embodiments of the invention, the inlet direction DI further has a radial component of absolute value less than the absolute value of the radial component of the outlet direction D2, for each purge hole 64. Thus, the inlet axis A1 is also less inclined radially inwards than the outlet axis A2, and the radial inclination pi of the inlet direction DI is thus less than the radial inclination 2 of the outlet direction D2.
[0092] Thus, in the example illustrated by figures 12 and 13, the radial inclination of the input direction DI is zero.
[0093] Figures 14 to 15C relate to a variant of the invention, in which the radial inclination pi of the input direction DI is non-zero, for illustration purposes.
Claims
Claims 1. Injection system for injecting a mixture of air and fuel into a turbomachine combustion chamber, comprising a sleeve (52) for receiving a fuel injector nozzle, a bowl (60), and at least one air intake swirler (56) arranged axially between the sleeve (52) and the bowl (60) for injecting air into the injection system having a rotating movement in a circumferential swirl direction (SCI) around an injection axis (44) of the injection system, in which the sleeve comprises a downstream end wall (62) defining, on an upstream side of the injection system, an upstream external surface (62A) of the latter, and on an opposite side, an upstream internal surface (62B) delimiting upstream said air intake swirler (56),and wherein said downstream end wall (62) comprises purge holes (64) each having an inlet (64A) opening through said upstream external surface (62A) and an outlet (64B) opening through said upstream internal surface (62B), wherein said inlet (64A) has an inlet axis (A1) oriented in an inlet direction (D1), and said outlet (64B) has an outlet axis (A2) oriented in an outlet direction (D2), wherein at least the outlet direction (D2) has a circumferential inclination (0, 02), defined by reference to a cylindrical coordinate system centered on the injection axis (44), and in the same direction as said circumferential spin direction (SCI), characterized in that each purge hole (64) is of curved shape, so that the inlet direction (D1) has a circumferential inclination (01), defined by reference cylindrical coordinate system audit,less than the circumferential inclination (02) of the outlet direction (D2), for each purge hole (64)., 2. Injection system according to claim 1, in which the outlet direction (D2) has a radial inclination (P, 2) in the direction of the injection axis (44).
3. Injection system according to claim 1, wherein the outlet direction (D2) is orthogonal to the radial direction (R') of said cylindrical coordinate system.
4. Injection system according to any one of claims 1 to 3, wherein each purge hole (64) is cylindrical in shape, whereby the inlet axis (A1) and the outlet axis (A2) of each purge hole (64) are coincident.
5. Injection system according to any one of claims 1 to 4, in which the circumferential inclination (01) of the entry direction (Dl) is zero.
6. Injection system according to any one of claims 1 to 5, in which the inlet direction (D1) has a radial inclination (pi), defined with reference to said cylindrical coordinate system, less than or equal to the radial inclination (P2) of the outlet direction (D2), for each purge hole (64).
7. Injection system according to claim 6, wherein the radial inclination (pi) of the inlet direction (Dl) is zero.
8. Turbomachine for aircraft, comprising a combustion chamber (16) and at least one injection system (42) according to any one of claims 1 to 7 for supplying the combustion chamber with a mixture of air and fuel.