Turbine combustion chamber

Abstract

An annular combustion chamber (10) of an aeronautical turbine engine along a longitudinal axis (X), comprising an annular row of injection systems (50) comprising at least one bowl (60) located downstream of a swirler (52, 54) and having a flared wall (62) widening in the downstream direction and extending around a bowl axis (B) to create an air / fuel mixing layer (100), the flared wall (62) comprises at least a first type region (62a) and a second type region (62b) at which the opening of the flared wall (62) widens in the downstream direction at at least a first flaring angle (alpha1) and at least a second flaring angle (alpha2), respectively, the second flaring angle being greater than the first flaring angle (alpha1), such that the air / fuel mixing layer (100) from the bowl (60) has at least one local widening (102) capable of intercepting an adjacent fuel layer (100).

Description

Field of the Invention

[0001] The present invention relates to a combustion chamber for an aero-turbine engine. The present invention also relates to a turbine engine including such a combustion chamber. Background Art

[0002] It is known that an annular combustion chamber of a turbine engine receives an air flow from an upstream high-pressure compressor and delivers a hot air flow downstream to drive the rotors of high-pressure and low-pressure turbines.

[0003] The annular combustion chamber includes two coaxial rotating walls which are nested with each other and are interconnected at their upstream ends by an annular bottom wall of the combustion chamber, which bottom wall has openings for mounting a fuel injection system between an inner ring and an outer ring.

[0004] Each injection system includes means for supporting a fuel nozzle head and at least one swirler which is arranged downstream of and coaxially with the nozzle head for delivering an air flow downstream of the fuel injection to form an air / fuel mixture for combustion in the combustion chamber.

[0005] The swirler of the injection system receives air from an annular diffuser at the outlet of the high-pressure compressor mounted upstream of the combustion chamber. Each injection system includes a mixing bowl to which each swirler delivers downstream. The mixing bowl includes a downstream wall which is generally frustoconical and which expands outwards in the downstream direction and may include a row of annular air injection holes evenly distributed around the axis of the mixing bowl.

[0006] The outer annular wall of the combustion chamber includes a row of annular holes for primary dilution and at least one spark plug, the electrode ends of which are exposed inside the combustion chamber.

[0007] During operation, the air discharged from the high-pressure compressor circulates inside each injection system. The air / fuel mixture is ejected from each injection system to form an air / fuel layer which is generally frustoconical and widens in the downstream direction. Moreover, the larger the diameter of the holes of the mixing bowl, the greater the air flow rate through each hole and the smaller the widening of the air / fuel mixing layer.

[0008] The primary dilution holes allow a combustion flame to be stabilized at the bottom of the chamber and, by diluting the air / fuel mixture, prevent the combustion flame from detaching and entering the high-pressure turbine, avoiding damage to components such as blades due to the formation of hot spots.

[0009] In fact, the injection systems are configured such that for each injection system, the air / fuel mixing layer meets or intercepts the fuel layers of two adjacent injection systems circumferentially upstream of the dilution holes. In this way, the circumferential continuity of the air / fuel mixture between the injection systems is ensured before dilution, thus guaranteeing that the flame initiated by the spark plug will propagate over the entire circumference of the combustion chamber.

[0010] In certain configurations, particularly in so-called "converging" combustion chambers, the swirler walls of the inner and outer annuli are frustoconical walls with a cross-sectional area that decreases in the downstream direction, or when the number of injection systems is reduced, the circumferential pitch between adjacent injection systems is greater. As a result, the fuel layers of adjacent injection systems no longer intercept each other circumferentially upstream of the primary dilution holes, which causes difficulties in the circumferential propagation of the flame between the injectors and reduces the performance of the combustion chamber.

[0011] Increasing the number of nozzles to overcome this drawback is not desirable because it would lead to an increase in the weight of the turbomachine. Uniformly increasing the flare angle of the fuel layer is also unsatisfactory because it would direct more fuel towards the inner and outer annulus walls and create hot spots on the inner and outer annulus walls.

[0012] Document FR 2 980 554 is also known, which proposes a solution to overcome these difficulties. FR 2980 554 describes a mixing bowl in which the distribution and size of the holes are such that the air / fuel mixing layer has at least one local widening that circumferentially intercepts adjacent fuel layers. However, it has been found that the positioning of the holes on the mixing bowl does not allow two adjacent layers to overlap far enough upstream to optimize flame propagation. In addition, modifying the distribution and size of the holes has an adverse effect on the control of the flare of the air / fuel mixing layer at different operating speeds of the turbomachine.

[0013] The present invention aims in particular to propose a simple, economical and effective solution to solve the above problems and thus avoid the drawbacks of the prior art. Summary of the Invention

[0014] There is proposed an annular combustion chamber for an aero-turbomachine having a longitudinal axis, comprising an annular row of injection systems, each injection system comprising:

[0015] - a fuel nozzle;

[0016] - at least one swirler configured to generate an air flow downstream of the fuel nozzle;

[0017] - a bowl located downstream of the swirler, the bowl comprising a flare wall that widens in the downstream direction and extends around the bowl axis to generate an air / fuel mixing layer that is generally frustoconical around the bowl axis, the flare wall comprising at least one first type region where the openings of the flare wall expand in the downstream direction at at least a first flare angle, and at least one second type region where the openings of the flare wall expand in the downstream direction at at least a second flare angle, the second flare angle being greater than the first flare angle, the second type regions being circumferentially arranged around the bowl axis such that the air / fuel mixing layer from the bowl has at least one local widening that can circumferentially intercept adjacent fuel layers.

[0018] Such a combustion chamber can ensure the circumferential continuity between each air / fuel mixing layer, thus ensuring good circumferential propagation of the combustion flame without increasing the number of nozzles. Indeed, the injection angle of the layer is a function of the flare angle of the mixing bowl wall. Moreover, different from the solution of FR 2 980 554, in which the local widening of the layer is obtained by modifying the distribution and size of the holes formed in the bowl wall, the local widening of the layer here is obtained through a second type of region in the flared wall of the bowl, which has a larger flare angle. The results show that, compared with the solution of FR 2 980 554, this can achieve a greater local increase in the injection angle of the layer. Therefore, compared with the solution of FR 2 980 554, the air / fuel mixing layer can intercept the adjacent layer circumferentially at a more upstream position. Thus, the interception area between two circumferentially adjacent layers is larger, which makes the circumferential propagation of the flame in the combustion chamber better. Another result is that the number of injection systems can be further reduced, or the spacing between two circumferentially adjacent injection systems can be further increased.

[0019] In addition, since the interception of circumferentially adjacent layers occurs at a more upstream position, better fuel atomization in the combustion chamber is observed, thus achieving better combustion performance.

[0020] In other words, the opening of the flared wall can extend downstream at a first flare angle less than or equal to a predetermined angle or threshold in the first type of region, and the opening of the flared wall can extend downstream at a second flare angle greater than the predetermined angle or threshold in the second type of region.

[0021] The opening of the flared wall leads to each of the first type of region and the second type of region. It should be understood that the first type of region and the second type of region each extend in the direction of the bowl axis to the downstream end of the flared wall. In other words, the downstream ends of the first type of region and the second type of region coincide with the downstream end of the flared wall.

[0022] In a cross-section perpendicular to the bowl axis, the air / fuel mixing layer can have a first dimension greater than a second dimension in the radial direction relative to the longitudinal axis in the circumferential direction around the longitudinal axis.

[0023] The flared wall may include at least one groove extending along the bowl axis and opening at least downstream of the flared wall. The bottom of such at least one groove may define the at least one second type domain. A groove refers to a groove or notch made at the thickness of the bowl, at the flared wall. Such at least one groove may have edges on both sides of the bottom, extending circumferentially with respect to the bowl axis. Each edge may connect the second type region defined by the corresponding groove and the (one or more) first type regions directly adjacent to the second type region defined by the corresponding groove. At each edge, the flare angle of the flared wall may change rapidly downstream between a first flare angle and a second flare angle. At each edge, there may be a downstream discontinuity in the flare angle of the flared wall between the first flare angle and the second flare angle.

[0024] The bowl axis may extend in a direction including a longitudinal component and a radial component with respect to the longitudinal axis. In a particular case, the bowl axis may be parallel to the longitudinal axis. In other words, the bowl axis may extend in a direction including only a longitudinal component.

[0025] The second flare angle may be between the first flare angle and 180°.

[0026] The combustion chamber may include two coaxial annular walls around the longitudinal axis, an inner wall and an outer wall respectively, which are interconnected at their upstream ends by an annular chamber bottom wall including an annular row of holes for mounting an injection system.

[0027] The first type region and / or the second type region may form a basic part of a conical surface.

[0028] The first type region may extend along the direction of the bowl axis from the upstream end of the flared wall. In other words, the upstream end of the first type region may coincide with the upstream end of the flared wall.

[0029] The second type region may extend along the direction of the bowl axis from the upstream end of the flared wall or from an intermediate position between the upstream end and the downstream end of the flared wall. In other words, the upstream end of the second type region may coincide with the upstream end of the flared wall or an intermediate position between the upstream end and the downstream end of the flared wall. Similarly, the at least one groove may extend along the direction of the bowl axis from the upstream end of the flared wall or from an intermediate position between the upstream end and the downstream end of the flared wall. If the at least one groove extends from the upstream end of the flared wall, it opens at the upstream of the flared wall.

[0030] The first type of region and / or the second type of region may have a cross-section with an arc shape around the bowl axis. In other words, each cross-section of each first type of region and / or second type of region has a cross-section with an arc shape around the bowl axis relative to the bowl axis. The opening of the flared wall expands downstream at at least a first single flare angle in at least one first type of region and / or at at least a second single flare angle in at least one second type of region. In a given cross-section of the flared wall, the first type of region may extend within an angular sector greater than that of the second type of region. Each cross-section of each second type of region extends within an angular sector around the bowl axis, the angular sector being between 10° and 90°, preferably between 20° and 45°. Each second type of region may include an upstream end portion and a downstream end portion. The downstream end portion extends within an angular sector around the bowl axis that is greater than or equal to the angular sector within which the upstream end portion extends around the bowl axis. Each cross-section of each first type of region extends within an angular sector around the bowl axis, the angular sector being between 90° and 170°, preferably between 135° and 160°. Each first type of region may include an upstream end portion and a downstream end portion. The downstream end portion extends to form an angular sector around the bowl axis that may be greater than or equal to the angular sector within which the upstream end portion extends around the bowl axis.

[0031] The second type of region may be positioned at the 3 o'clock or 9 o'clock angular position around the bowl axis.

[0032] The injection system may be adapted such that the flow of the air / fuel mixture within the flared wall rotates around the bowl axis in a first rotational direction, clockwise or counterclockwise. The second type of region may be positioned between the following positions around the bowl axis:

[0033] - When the rotational direction is clockwise, between the 12 o'clock angular position and the 3 o'clock angular position, or between the 6 o'clock angular position and the 9 o'clock angular position; or

[0034] - When the rotational direction is counterclockwise, between the 9 o'clock angular position and the 12 o'clock angular position, or between the 3 o'clock angular position and the 6 o'clock angular position.

[0035] The at least one groove may have a spiral shape around the bowl axis, and its rotational direction coincides with the first rotational direction.

[0036] Such a flared wall may form a local widening to intercept adjacent fuel layers, taking into account the rotational movement of the air / fuel mixture.

[0037] In other words, when the first direction coincides with the clockwise direction, the air / fuel mixture within the flare wall flows around the bowl axis through consecutive angular positions of 12 o'clock, 3 o'clock, 6 o'clock, and 9 o'clock; when the first direction coincides with the counterclockwise direction, the air / fuel mixture within the flare wall flows around the bowl axis through consecutive angular positions of 12 o'clock, 9 o'clock, 6 o'clock, and 3 o'clock. Accordingly, the air / fuel mixture exhibits a helical motion around the bowl axis within the flare wall of the bowl.

[0038] The second type of region may be in a conical helical shape around the bowl axis, and its direction of rotation around the bowl axis coincides with the first direction of rotation. Thus, when the direction of rotation of the mixture flow coincides with the clockwise direction, the upstream end of the second type of region may be closer to the 12 o'clock or 6 o'clock angular position around the bowl axis rather than the downstream end of the second type of region. When the direction of rotation of the mixture flow coincides with the counterclockwise direction, the upstream end of the second type of region may be closer to the 9 o'clock or 3 o'clock angular position around the bowl axis rather than the downstream end of the second type of region.

[0039] The flare wall may include at least a first second type of region and a second second type of region. The flare wall may include at least a first groove and a second groove, which respectively define the first second type of region and the second second type of region. The flare wall may include at least a first first type of region and a second first type of region. The flare wall may circumferentially alternate the first type of region and the second type of region around the bowl axis. Each first type of region is circumferentially located between two grooves around the bowl axis.

[0040] The first second type of region and the second second type of region may cause the flare wall to have at least second-order rotational symmetry with respect to the bowl axis. The first groove and the second groove may cause the flare wall to have second-order rotational symmetry with respect to the bowl axis. In other words, the cross-section of the flare wall perpendicular to the bowl axis remains unchanged under any 180° rotation around the bowl axis.

[0041] The first second type of region and the second second type of region may be located on both sides of a first intermediate plane including the longitudinal axis and the bowl axis. The first groove and the second groove may be located on both sides of a first intermediate plane including the longitudinal axis and the bowl axis. Accordingly, the air / fuel mixing layer has two local widening portions, which are located on both sides of the first intermediate plane and are each adapted to circumferentially intercept the corresponding adjacent fuel layers. Thereby, flame propagation is improved.

[0042] The first second type of region and the second second type of region may cause the flare wall to be symmetric with respect to the first intermediate plane. The first groove and the second groove may cause the flare wall to be symmetric with respect to the first intermediate plane. This symmetry can avoid imbalance in the combustion chamber.

[0043] The first and second type regions may be positioned at the 3 o'clock angular position around the bowl axis, and the second and second type regions may be positioned at the 9 o'clock angular position around the bowl axis.

[0044] The flare wall may include at least a third and a fourth second type region, with the first and second second type regions located on a first side of a second intermediate plane that includes the bowl axis and an axis passing through the 3 o'clock and 9 o'clock angular positions, and the third and fourth second type regions located on a second side of the second intermediate plane. The flare wall may include at least a third groove and a fourth groove that respectively define the third and fourth second type regions. This configuration allows for better fuel atomization in a preferred direction that coincides with the angular position of each second type region. Additionally, bowl holes may be provided circumferentially around the bowl axis between the first and third second type regions and between the second and fourth second type regions. More generally, the flare wall may include n second type regions, where n is an integer greater than or equal to 2. The flare wall may be symmetric with respect to the first intermediate plane and / or the second intermediate plane.

[0045] The flare wall may be symmetric with respect to the second intermediate plane.

[0046] The first type region and / or the second type region may be in the shape of an elliptical arc around the bowl axis in a cross-section perpendicular to the bowl axis. The flare wall may have an elliptical cross-section perpendicular to the bowl axis. The flare wall may extend downstream at a first flare angle at the 12 o'clock and 6 o'clock angular positions and at a second flare angle at the 3 o'clock and 9 o'clock angular positions. The flare angle of the flare wall may vary linearly between the first flare angle and the second flare angle between each pair of consecutive angular positions among the 12 o'clock, 3 o'clock, 6 o'clock, and 9 o'clock angular positions.

[0047] The flare wall may include a plurality of bowl holes. The bowl holes may be distributed around the bowl axis. The bowl holes may be formed in the first type region of the flare wall. When the flare wall includes a plurality of first type regions, the bowl holes may be grouped and distributed. Each bowl hole in each group may be formed in one first type region. Alternatively, the bowl holes may be evenly distributed around the bowl axis. An annular row of bowl holes may be provided. In particular, each first type region and each second type region may include one or more bowl holes.

[0048] The bowl may include an annular radial wall around the bowl axis that extends radially from the downstream end of the flare wall with respect to the bowl axis.

[0049] The bowl may include a cylindrical wall extending along the bowl axis, with the flare wall located downstream of the cylindrical wall. The cylindrical wall may have a circular cross-section.

[0050] According to another aspect, there is provided an aero-turbine engine including the above combustion chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Other features, details and advantages will become apparent upon reading the following detailed description and analyzing the accompanying drawings, in which:

[0052] Figure 1 shows a longitudinal cross-sectional view of a turbine engine combustion chamber according to the present invention;

[0053] Figure 2 shows Figure 1 a cross-sectional view of the injection system of the combustion chamber shown;

[0054] Figure 3 shows a perspective view of the injection system shown according to a preferred embodiment Figure 2 ;

[0055] Figure 4 shows Figure 3 a front view of the injection system shown;

[0056] Figure 5 shows Figure 3 a cross-sectional view of the injection system shown;

[0057] Figure 6 includes Figure 6 a and Figure 6 b, showing respectively Figure 2 a top view of the injection system shown and an air / fuel mixing layer formed by the injection system, and a cross-sectional view of the air / fuel mixing layer;

[0058] Figure 7 shows Figure 1 a partial perspective view of the combustion chamber shown, in particular two circumferentially adjacent air / fuel mixing layers;

[0059] Figure 8 shows a front view of the injection system shown according to another embodiment Figure 2 ;

[0060] Figure 9 shows a front view of the injection system shown according to another embodiment Figure 2 ;

[0061] Figure 10 shows a front view of the injection system shown according to another embodiment Figure 2 ;

[0062] Figure 11 shows a front view of the injection system shown according to another embodiment Figure 2 .​​​​​​​​​​​ Detailed implementation mode

[0063] First, refer to Figure 1 , which shows an annular combustion chamber 10 of a turbine engine along the longitudinal axis X, such as an aero-turbine engine or a turboprop engine, which is arranged at the outlet of a centrifugal diffuser 12, and the centrifugal diffuser is installed at the outlet of a high-pressure compressor (not shown). Behind the combustion chamber 10 is a high-pressure turbine 14, and only its inlet nozzle is shown.

[0064] In the present invention, the longitudinal direction corresponds to the direction of the longitudinal axis X. The longitudinal axis X coincides with the rotation axis of the rotor component of the turbine engine. Unless otherwise specified, orientation terms such as "longitudinal", "radial" or "circumferential" are defined relative to the longitudinal axis X. The radial direction is the direction perpendicular to the longitudinal axis X. At a point at a distance from the longitudinal axis X, the circumferential direction corresponds to the direction perpendicular to the axial and radial directions. In addition, unless otherwise specified, the adjectives "inner", "internal", "outer" and "external" are used relative to the radial direction, so that the inner / inner (i.e., radially inner / inner) part of an element is closer to the longitudinal axis X than the outer / outer (i.e., radially outer / outer) part of the same element. Finally, the relative terms "upstream" and "downstream" are defined relative to the normal flow direction of the fluid in the turbine engine (from upstream to downstream).

[0065] The combustion chamber 10 includes two coaxial inner 16 and outer 18 rotating frustoconical walls, which are nested with each other and the cross-sectional area decreases in the downstream direction. Such a combustion chamber 10 is called a convergent combustion chamber. The inner 16 and outer 18 annular walls are connected to the annular chamber bottom wall 20 at their upstream ends and are fixed by inner 22 and outer 24 annular flanges at their downstream ends. The outer annular flange 24 abuts against the outer shell 26 radially on the outside and abuts against the radial flange 28 for fixing the distributor of the high-pressure turbine 14 to the outer shell 26 axially. The inner annular flange 22 of the combustion chamber 10 abuts against the inner annular component 30 radially and axially to fix the distributor to the inner annular wall 32.

[0066] The bottom 20 of the chamber 10 has an opening for installing the system 50 to inject the air-fuel mixture into the bowl, the air comes from the centrifugal diffuser 12, and the fuel is supplied by the nozzle 34.

[0067] The nozzle 34 is fixed to the outer shell 26 at its radially outer end and is evenly distributed around the longitudinal axis X in a circumference. Each nozzle 34 has a fuel injection head 36 at its radially inner end, and the fuel injection head is aligned with the axis of the corresponding opening in the chamber bottom 20.

[0068] The air / fuel mixture in the injection chamber is ignited by at least one spark plug 38 that extends radially outside the chamber. The inner end of the spark plug extends into a hole in the outer wall 18 of the chamber, and its radially outer end is fixed to the housing 26 in a suitable manner and connected to a power supply device (not shown) located outside the housing.

[0069] The outer annular wall 18 of the combustion chamber 10 includes annular primary dilution holes 40 for diluting the air / fuel mixture, which are arranged upstream of the spark plug 38.

[0070] Each injection system 50, as most clearly shown, includes two coaxial upstream 52 and downstream 54 swirlers, which are upstream connected to means for centrally positioning and guiding the head of the nozzle 34 and downstream connected to a mixing bowl 60, which is axially mounted at an opening in the bottom wall 20 of the chamber. The swirlers 52, 54 may each include a plurality of vanes that extend radially along the swirler axis and are evenly distributed around the axis to convey the air flow downstream of the fuel nozzle orifice 36. Figure 2

[0071] The swirlers 52, 54 are separated from each other by a wall 56 that is radial with respect to the bowl axis B, and this wall is connected at its radially inner end with respect to the bowl axis B to a venturi 58 that extends axially downstream inside the downstream swirler 54 and separates the air flows from the upstream 52 and downstream 54 swirlers. A first annular air flow passage is formed inside the venturi 58, and a second annular air flow passage is formed outside the venturi 58.

[0072] Figures 3 to 5 As more particularly visible, the bowl 60 includes a flared wall 62 that extends around the bowl axis B and expands at at least one flaring angle α in the downstream direction to produce a generally frustoconical air / fuel mixing layer 100 around the bowl axis B. The bowl axis B extends here in a direction that includes a longitudinal direction component and a radial direction component with respect to the longitudinal axis X.

[0073]

[0074] The bowl 60 includes a cylindrical wall 64 that extends along the bowl axis B, and the flared wall 62 is located downstream of the cylindrical wall 64. The cylindrical wall 64 enables the flared wall 62 to be connected to the downstream swirler 54. Here, the cylindrical wall 64 has a circular cross-section. The bowl 60 includes an annular radial wall 66 around the bowl axis B, which extends radially from the downstream end of the flared wall 62 with respect to the bowl axis B.

[0074] According to the example shown, the flared wall 62 includes a first region 62a of a first type and a second region 62a' of the first type, at which regions the opening of the flared wall 62 expands in the downstream direction at a first flare angle α1. The flared wall 62 further includes a first region 62b of a second type and a second region 62b' of the second type, at which regions the opening of the flared wall 62 expands in the downstream direction at a second flare angle. For this purpose, the flared wall 62 includes a first groove 63 and a second groove 63', the bottoms of which respectively define the first region 62b of the second type and the second region 62b' of the second type. The bottom of the first groove 63 defines the first region 62b of the second type. The bottom of the second groove 63' defines the second region 62b' of the second type. Here, the flared wall 62 includes regions 62a, 62a' of the first type and regions 62b, 62b' of the second type that are circumferentially alternating around the bowl axis B. As described below, more than two regions of the first type and more than two regions of the second type can be provided. Each region 62a, 62a' of the first type is circumferentially located between two grooves 63, 63' around the bowl axis B. In other words, the grooves 63, 63' circumferentially define the regions 62a, 62a' of the first type on each side around the bowl axis B.

[0075] The "groove" is understood to be a groove or notch made in the thickness of the bowl 60 at the flared wall 62. Each groove 63 may include an edge 65, one on each circumferential side thereof relative to the bowl axis. Each edge includes a bottom or bottom wall between its respective edges. The first groove 63 includes an edge 65 connecting the first region 62b of the second type and the first region 62a of the first type, and another edge 65 connecting the first region 62b of the second type and the second region 62a' of the first type. Similarly, the second groove 63' includes an edge 65 connecting the second region 62b' of the second type and the first region 62a of the first type, and another edge 65 connecting the second region 62b' of the second type and the second region 62a' of the first type. At each edge 65, the flare angle at the outlet of the flared wall may change rapidly or suddenly between the first flare angle and the second flare angle. In particular, at each edge 65, the flare angle at the outlet of the flared wall may be discontinuous.

[0076] Note that the second flaring angle α2 is greater than the first flaring angle α1. The flaring angle of the flaring wall 62 is determined with respect to the direction of the bowl axis B. In other words, at each first type region 62a, 62a', the opening of the flaring wall 62 extends at a first flaring angle α1 that is less than or equal to a predetermined angle or threshold in the downstream direction, while at each second type region 62b, 62b', the opening of the flaring wall 62 extends at a second flaring angle greater than the predetermined angle or threshold in the downstream direction. The predetermined angle or threshold thus lies between the first flaring angle α1 and the second flaring angle α2. In a particular case, the first flaring angle α1 is equal to the predetermined angle or threshold. The second flaring angle can thus be, for example, between the first flaring angle α1 and 180°.

[0077] Furthermore, each second type region 62b, 62b' is circumferentially positioned around the bowl axis B such that the air / fuel mixture layer 100 from the flaring wall 62 has at least one local widening 102 that can circumferentially intercept an adjacent fuel layer 100.

[0078] The positioning of the first type regions 62a, 62a' and the second type regions 62b, 62b' around the bowl axis B is expressed as the angular position of the circumferential middle part around the bowl axis B relative to the downstream end of the bowl axis B. The angular position of each first type region 62a, 62a' and second type region 62b, 62b' is determined relative to a clock face (viewed, for example, from downstream here), where the angular positions of 12 o'clock, 3 o'clock, 6 o'clock and 9 o'clock are positioned in a conventional manner on the clock face. The angular positions of 12 o'clock and 6 o'clock are located on a radial axis with respect to the longitudinal axis X. The 6 o'clock position is radially inward relative to the 12 o'clock position. The angular positions of 3 o'clock and 9 o'clock are located on an axis whose direction coincides with the circumferential direction at the intersection of the bowl axis B and the radial axis of the 12 o'clock and 6 o'clock positions. The axis radially extending through the 12 o'clock and 6 o'clock angular positions is thus perpendicular to the axis passing through the 3 o'clock and 9 o'clock angular positions.

[0079] In this case, the first slot 63 (or the first second-type region 62b) is at the 3 o'clock position in the angular position around the bowl axis B, and the second slot (or the second second-type region 62b') is at the 9 o'clock position in the angular position around the bowl axis B. In addition, the first first-type region 62a is at the 12 o'clock position in the angular position around the bowl axis B, and the second first-type region 62a' is at the 6 o'clock position in the angular position around the bowl axis B. Therefore, the first slot 63 and the second slot 63' are located on both sides of the first intermediate plane defined by the longitudinal axis X and the bowl axis B. In particular, the first slot 63 and the second slot 63' make the flared wall 62 symmetric with respect to the first intermediate plane. In other words, the first second-type region 62b and the second second-type region 62b' are located on both sides of the first intermediate plane defined by the longitudinal axis X and the bowl axis B. In particular, the first second-type region 62b and the second second-type region 62b' make the flared wall 62 symmetric with respect to the first intermediate plane.

[0080] Therefore, due to the correlation between the injection angle of the layer 100 and the flare angle of the flared wall 62, the second-type regions 62b, 62b' in the flared wall 62 of the bowl 60 allow the formation of an air / fuel mixture layer 100 from the flared wall 62, which has locally widened portions 102 on each side in the circumferential direction, as Figure 6 a and Figure 6 shown in b. In a cross-section perpendicular to the bowl axis B, the air / fuel mixture layer 100 thus has a first dimension D1 in the circumferential direction around the longitudinal axis X, which is larger than a second dimension D2 in the radial direction with respect to the longitudinal axis X.

[0081] This contributes to the superposition between two adjacent air / fuel mixture layers 100, as Figure 7 seen, which ensures good circumferential propagation of the combustion flame without adding the nozzle 34. Such an injection system 50 also allows the air / fuel mixture layer 100 to intercept adjacent layers 100 circumferentially at a more upstream location. Therefore, the interception area between two circumferentially adjacent layers 100 is larger, which allows better circumferential propagation of the flame in the combustion chamber 10. Another result is that the number of injection systems 50 can be further reduced, or the spacing between two circumferentially adjacent injection systems 50 can be further increased. In addition, since the interception of circumferentially adjacent layers 100 occurs at a more upstream location, better fuel atomization is observed in the combustion chamber 10, which allows better combustion performance.

[0082] The opening of the flared wall 62 leads to each of the first type region 62a and the second type region 62b. It should be understood here that each first type region 62a, 62a’ and / or each second type region 62b, 62b’ extends in the direction of the bowl axis B to the downstream end of the flared wall 62. In other words, the downstream ends of each first type region 62a, 62a’ and each second type region 62b, 62b’ coincide with the downstream end of the flared wall 62. Further, each first type region 62a, 62a’ and each second type region 62b, 62b’ extends in the direction of the bowl axis B here, starting from the upstream end of the flared wall 62. In other words, the upstream ends of each first type region 62a, 62a’ and each second type region 62b, 62b’ coincide with the upstream end of the flared wall 62. Thus, each first type region 62a, 62a’ and each second type region 62b, 62b’ extends in the direction of the bowl axis B throughout the entire length of the flared wall 62 in the direction of the bowl axis B. In other words, the first groove 63 and the second groove 63’ each extend from the upstream end of the flared wall 62 to the downstream end of the flared wall 62. Further, the first groove and the second groove 63’ open both upstream and downstream of the flared wall. Alternatively, the first groove 63 and / or the second groove 63' may start from upstream and extend from an intermediate position between the upstream end and the downstream end of the flared wall to the downstream end of the flared wall.

[0083] According to Figures 3 to 5 the example of, each first type region 62a, 62a' and each second type region 62b, 62b' forms a basic conical surface portion. Thus, each generatrix of each first type region 62a, 62a' has a single flare angle equal to the first flare angle α1, and each generatrix of each second type region 62b, 62b' has a single flare angle equal to the second flare angle α2. Alternatively, it may also be specified that each first type region 62a, 62a’ and / or each second type region 62b, 62b’ forms a basic hyperboloid surface portion, that is, each generatrix of each first type region 62a, 62a’ and / or each second type region 62b, 62b’ has a flare angle that varies according to the direction of the bowl axis B.

[0084] The cross-sectional shape of each of the first-type regions 62a, 62a' and each of the second-type regions 62b, 62b' is also an arc shape around the bowl axis B. In other words, each cross-section of each of the first-type regions 62a and / or each of the second-type regions 62b relative to the bowl axis has a cross-section with an arc shape around the bowl axis B. Further, here, the opening of the flared wall 62 extends in the downstream direction at at least a first single flare angle α1 at the at least one first-type region 62a and / or at at least a second single flare angle α2 at the at least one second-type region 62b. Further, in a given cross-section of the flared wall 62 (i.e., perpendicular to the bowl axis B), each of the first-type regions 62a, 62a' extends in a larger angular section than each of the second-type regions 62b, 62b'. In the example shown, in a given cross-section of the flared wall 62, each of the first-type regions 62a, 62a' extends in a first angular section, and each of the second-type regions 62b, 62b' extends in a second angular section.

[0085] Each cross-section of each of the second-type regions 62b, 62b' extends in an angular section around the bowl axis B relative to the bowl axis B, and the angular section is between 10° and 90°, preferably between 20° and 45°. The two cross-sections in one second-type region may have different angular sections from each other. Each of the second-type regions 62b, 62b' may include an upstream end cross-section and a downstream end cross-section. In the example shown, the angular section that the downstream end cross-section extends around the bowl axis is greater than or equal to the angular section that the upstream end cross-section extends around the bowl axis.

[0086] Each cross-section of each of the first-type regions 62a extends in an angular section around the bowl axis B relative to the bowl axis B, and the angular section is between 90° and 170°, preferably between 135° and 160°. The two cross-sections in one first-type region may have different angular sections from each other. Each of the first-type regions 62a, 62a' may include an upstream end cross-section and a downstream end cross-section. The angular section that the downstream end cross-section extends around the bowl axis may be greater than or equal to the angular section that the upstream end cross-section extends around the bowl axis.

[0087] Finally, the flared wall 62 includes a plurality of air injection bowl holes 70. The bowl holes 70 are distributed around the bowl axis B. The bowl holes 70 are formed in each of the first type regions 62a, 62a' of the flared wall 62. Thus, the bowl holes 70 are grouped and distributed: each bowl hole 70 in a group is formed in one of the first type regions 62a, 62a'. Each of the second type regions 62b, 62b' thus has no bowl holes 70. Advantageously, the size or arrangement of the bowl holes 70 is not changed by the local widening 102 of the forming layer 102. Thus, the size and arrangement of the bowl holes are not limited by the circumferential overlap requirements between the layers 100. Thus, the size and arrangement of the bowl holes 70 can be advantageously determined according to the widening of the layer 100 better controlled at different operating speeds of the turbomachine.

[0088] Now refer to Figure 8 , which shows another embodiment of the injection system 50 described above. The flared wall 62 here includes a third second type region 62b'' and a fourth second type region 62b'''. In this case, the flared wall 62 includes a third groove and a fourth groove, the bottoms of which respectively define the third second type region (62b'') and the fourth second type region (62b'''). The first groove 63 and the second groove 63' are located on a first side of a second intermediate plane that includes the bowl axis B and the axis passing through the 3 o'clock and 9 o'clock angular positions. The third groove 63'' and the fourth groove 63''' are located on a second side of the second intermediate plane. In other words, the first second type region 62b and the second second type region 62b' are located on a first side of a second intermediate plane that includes the bowl axis B and the axis passing through the 3 o'clock and 9 o'clock angular positions. The third second type region 62b'' and the fourth second type region 62b''' are located on a second side of the second intermediate plane. Here, the flared wall 62 is symmetric with respect to the first intermediate plane and the second intermediate plane. This configuration allows for better fuel atomization in a preferred direction that coincides with the angular position of each second type region. Additionally, in this case, at the 3 o'clock angular position, bowl holes 70 are provided circumferentially around the bowl axis B between the first second type region 62b and the third second type region 62b''. Similarly, at the 9 o'clock angular position, bowl holes 70 are provided circumferentially around the bowl axis B between the second second type region 62b' and the fourth second type region 62b'''.

[0089] It should also be noted that each of the second type regions 62b, 62b' extends in the direction of the bowl axis B from an intermediate position between the upstream end and the downstream end of the flared wall 62. In other words, the upstream end of each of the second type regions 62b, 62b' coincides with an intermediate position between the upstream end and the downstream end of the flared wall.

[0090] Now refer to Figure 9, which shows another embodiment of the above-described injection system 50. It can be provided that the air / fuel mixture has a helical (i.e., rotational) motion around the bowl axis B within the flared wall 62 of the bowl 60. Thus, the injection system 50 (especially the swirler) is adapted here such that the flow of the air / fuel mixture within the flared wall 62 rotates around the bowl axis B in a first rotational direction S1, where the first rotational direction coincides with the clockwise direction. For this purpose, each groove is helical in shape around the bowl axis B, and its rotational direction coincides with the first rotational direction S1. The angular positions of the first second-type regions 62b and the second second-type regions 62b' around the bowl axis B are respectively between the angular positions of 12 o'clock and 3 o'clock, and between the angular positions of 6 o'clock and 9 o'clock. Such a flared wall 62 enables local widening 102 to be formed circumferentially on each side of the layer 100, taking into account the rotational motion of the air / fuel mixture. Each second-type region 62b, 62b' is helical in shape around the bowl axis B in a conical manner, and its rotational direction around the bowl axis B coincides with the first rotational direction S1. This achieves better flow guidance by adapting its rotational motion. Alternatively, the first rotational direction S1 can coincide with the counterclockwise direction.

[0091] According to Figure 9 the example, the flared wall 62 has a secondary rotational symmetry around the bowl axis B. In other words, the cross-section of the flared wall 62 perpendicular to the bowl axis B remains unchanged for any 180° rotational angle around the bowl axis B.

[0092] Figure 10 shows another embodiment, in which the bowl holes 70 are evenly distributed around the bowl axis B in an annular row of bowl holes. In particular, each first-type region 62a, 62a’ and each second-type region 62b, 62b’ include a plurality of bowl holes 70.

[0093] Finally, Figure 11 shows another embodiment, in which each first-type region 62a, 62a’ and each second-type region 62b, 62b’ form a basic conical surface and have a cross-sectional shape of an elliptical arc around the bowl axis B. Thus, for each first-type region 62a, 62a’ or second-type region 62b, 62b’, the flare angles α of any two generatrices are different from each other. In the variant described above with reference to Figures 3 to 10 (especially the variant including grooves), such an alternative is not excluded: the cross-section of each of one or more first-type regions is in the shape of an elliptical arc around the bowl axis B and / or the cross-section of each of one or more second-type regions is in the shape of an elliptical arc around the bowl axis B.

[0094] In addition, Figure 11The variant differs from the other variants in that the flaring wall 62 has no slots and its cross-section perpendicular to the bowl axis B is elliptical. Thus, the flaring wall 62 extends downstream at a first flaring angle α1 at the angular positions of 12 o'clock and 6 o'clock, and at a second flaring angle at the angular positions of 3 o'clock and 9 o'clock. The flaring angle of the flaring wall 62 varies linearly between the first flaring angle α1 and the second flaring angle α2, between each pair of consecutive angular positions among the angular positions of 12 o'clock, 3 o'clock, 6 o'clock and 9 o'clock.

[0095] In accordance with the above terms, in Figure 11 the example shown, the first and second first-type regions 62a' are respectively at the angular positions of 12 o'clock and 6 o'clock around the bowl axis B, and each region here extends within an angular section of 45°. Similarly, the first and second first-type regions 62a' are respectively at the angular positions of 3 o'clock and 9 o'clock around the bowl axis B, and each region here extends within an angular section of 45°. The threshold angle here corresponds to the flaring angle of the generatrix of the flaring wall 62 at the angular positions of 1:30, 4:30, 7:30 and 10:30 around the bowl axis B. The threshold angle can be, for example, the average of the first flaring angle α1 and the second flaring angle α2.

[0096] Different from Figure 11 the variant, the variant of the flaring wall including one or more slots ( Figures 3 to 10 ) has an additional degree of parameterization in terms of the bowl and its flaring angle at each slot, as the range (or dimension) of each slot along the bowl axis can be selected. As previously mentioned, the upstream end of one of the slots can coincide with the upstream end of the flaring wall or an intermediate position of the flaring wall along the bowl axis between the upstream end and the downstream end. This additional degree of parameterization allows for better control of the local widening of the layer 100. Furthermore, according to the variant of the flaring wall including one or more slots ( Figures 3 to 10 ), the air / fuel mixing layer 100 generated by the bowl includes a main layer generated by the first-type regions and one or more secondary layers generated by the second-type regions, each second-type region being bounded by the bottom of the slot. Each main layer and secondary layer has its own aerodynamic field of the air / fuel mixture, for example having its own rotational motion. This enables better atomization of the air / fuel mixture, thereby improving combustion performance, and also enables avoidance of the formation of a fuel film on the flaring wall, which may create overheated regions, instability or the formation of pollutants on the flaring wall.

Claims

1. An annular combustion chamber (10) of an aero-turbine engine along a longitudinal axis (X), comprising an annular injection system (50) row, at least one injection system (50) comprising: - a fuel nozzle (34); - at least one swirler (52, 54) configured to generate an air flow downstream of the fuel nozzle (34); - a bowl (60) located downstream of the swirler (52, 54), the bowl (60) comprising a flared wall (62) that widens in the downstream direction and extends around a bowl axis (B) to generate an air / fuel mixing layer (100) that is generally frustoconical around the bowl axis (B), the flared wall (62) comprising at least one first type region (62a) where the opening of the flared wall (62) expands in the downstream direction at at least a first flare angle (α1), the flared wall (62) comprising at least one slot (63; 63') extending along the bowl axis (B) and opening at least downstream of the flared wall (62), the bottom of the at least one slot defining a second type region (62b) of the flared wall (62) where the opening of the flared wall (62) expands in the downstream direction at at least a second flare angle (α2), the second flare angle being greater than the first flare angle (α1), the second type region (62b) being circumferentially arranged around the bowl axis (B) such that the air / fuel mixing layer (100) from the bowl (60) has at least one local widening (102) capable of circumferentially intercepting an adjacent fuel layer (100).

2. The combustion chamber (10) according to the preceding claim, characterized in that, Each cross-section of the at least one second type region (62b) extends within an angular sector around the bowl axis (B) having an angular range of 10° to 90°, preferably 20° to 45°, with respect to the bowl axis (B).

3. The combustion chamber (10) according to any one of the preceding claims, characterized in that, Each cross-section of the at least one first type region (62a) extends within an angular sector around the bowl axis (B) having an angular range of 90° to 170°, preferably 135° to 160°, with respect to the bowl axis (B).

4. The combustion chamber (10) according to any one of the preceding claims, characterized in that, The opening of the flared wall (62) widens in the downstream direction at at least a first single flare angle (α1) in the at least one first type region (62a) and / or at at least a second single flare angle (α2) in the at least one second type region (62b). The combustion chamber (10) according to any one of the preceding claims, characterized in that, The first type region and / or the second type region form a basic part of a conical surface.

6. The combustion chamber (10) according to any one of the preceding claims, characterized in that, Each cross-section of the first type region (62a) and / or the second type region (62b) has an arc shape around the bowl axis with respect to the bowl axis (B).

7. The combustion chamber (10) according to any one of the preceding claims, characterized in that, The second type region (62b) is at the 3 o'clock angular position or the 9 o'clock angular position around the bowl axis (B).

8. The combustion chamber (10) according to any one of the preceding claims, characterized in that, The injection system (50) is adapted such that the air / fuel mixture flows within the flared wall (62) around the bowl axis (B) in a first rotational direction (S1) that coincides with the clockwise or counterclockwise direction, and the second type region (62b) is at an angular position around the bowl axis (B): - when the rotational direction coincides with the clockwise direction, between the 12 o'clock angular position and the 3 o'clock angular position or between the 6 o'clock angular position and the 9 o'clock angular position; or - When the rotation direction coincides with the counterclockwise direction, it is between the 12 o'clock angular position and the 9 o'clock angular position or between the 6 o'clock angular position and the 3 o'clock angular position.

9. The combustion chamber (10) according to the preceding claims, characterized in that, The at least one groove (63; 63') has a spiral shape around the bowl axis (B), and its rotation direction coincides with the first rotation direction (S1).

10. The combustion chamber (10) according to any one of the preceding claims, characterized in that, The flared wall (62) includes at least a first groove (63) and a second groove (63'), which respectively define a first second-type region (62b) and a second second-type region (62b').

11. The combustion chamber according to the preceding claims, characterized in that, Each first-type region (62a) is circumferentially located between two grooves around the bowl axis (B).

12. The combustion chamber (10) according to the preceding claims, characterized in that, The first groove (63) and the second groove (63') give the flared wall (62) a secondary rotational symmetry around the bowl axis (B).

13. The combustion chamber according to claim 6 or 7, characterized in that, The first groove (63) and the second groove (63') are respectively located on both sides of a first intermediate plane containing the longitudinal axis (X) and the bowl axis (B).

14. The combustion chamber (10) according to the preceding claims, characterized in that, The first groove (63) and the second groove (63') make the flared wall (6) symmetric with respect to the first intermediate plane.

15. The combustion chamber (10) according to claim 8 or 9, characterized in that, The flared wall (62) includes at least a third groove (63”) and a fourth groove (63”'), each of the third groove and the fourth groove respectively defining a third second-type region (62b”) and a fourth second-type region (62b”'), and the first second-type region (62b) and the second second-type region (62b') are located on a first side of a second intermediate plane containing the bowl axis (B) and an axis passing through the 3 o'clock and 9 o'clock angular positions, and the third second-type region (62b”) and the fourth second-type region (62b”') are located on a second side of the second intermediate plane.

Images