RING CRANKCASE FOR A TURBOMACHINE OR A TURBOMACHINE TEST BENCH AND METHOD FOR TESTING THE AERODYNAMIC PERFORMANCE OF THE CRANKCASE
The annular housing with removable pockets simplifies crankcase geometry adjustments, enabling efficient aerodynamic testing on turbomachines by allowing direct modification and analysis on assembled systems.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- SAFRAN AIRCRAFT ENGINES SAS
- Filing Date
- 2024-05-02
- Publication Date
- 2026-05-22
AI Technical Summary
Existing turbomachine crankcases face challenges in accurately measuring aerodynamic impacts due to air separation downstream of suspension arms, and modifying housing geometry is complex and costly, making it difficult to test different configurations.
An annular housing with removable pockets that allow easy modification of geometry, enabling rapid testing of aerodynamic performance by mounting and dismounting these pockets directly on assembled turbomachines or test benches without full disassembly.
Facilitates simplified and economical adjustment of crankcase geometry for aerodynamic testing, allowing precise measurement of different configurations without heavy manufacturing processes.
Abstract
Description
Title of the invention: ANNULAR CRANKCASE FOR A TURBOMACHINE OR A TURBOMACHINE TEST BENCH AND METHOD FOR TESTING THE AERODYNAMIC PERFORMANCE OF THE CRANKCASE. Technical field of the invention
[0001] The present invention relates to an annular housing, in particular an exhaust housing, for a turbomachine or for a turbomachine test bench, as well as a method for testing the aerodynamic performance of such a housing. Technical background
[0002] An aircraft turbomachine includes a gas generator which conventionally comprises, from upstream to downstream, with reference to the gas flow in the turbomachine, at least one compressor, an annular combustion chamber, and at least one turbine. In the case of a twin-spool turbojet engine, with low-pressure and high-pressure cylinders respectively, the gas generator comprises successively a low-pressure compressor, a high-pressure compressor, the combustion chamber, a high-pressure turbine, and a low-pressure turbine. The rotor of the low-pressure compressor is driven by the rotor of the low-pressure turbine, and the rotor of the high-pressure compressor is driven by the rotor of the high-pressure turbine.
[0003] The gas generator also defines an annular flow channel for a gas stream that passes through the compressors, the combustion chamber, and the turbines. This channel is called the primary channel, and the gas stream flowing through it is called the primary stream.
[0004] At the downstream end of the primary flow, the gas generator includes an exhaust housing that forms the final housing of the turbomachine. This exhaust housing includes auxiliary arms and suspension arms. The suspension arms are characterized by recesses necessary for positioning yokes configured to allow the turbomachine to be suspended. A recess results in a local deformation of the outer wall, forming a recess on its outer surface and a protrusion on its inner surface. The recess facilitates the positioning of the yoke in radial alignment with the suspension arm.
[0005] During numerical simulations, air separation was detected downstream of the suspension arms, including the pockets. However, the tools of Numerical simulations do not allow us to understand the impact of the detachments on the rear of the crankcase body, and it is therefore necessary to carry out physical tests to accurately measure this impact.
[0006] Furthermore, in existing crankcases, the arms are cast and then welded to the exhaust crankcase. This is a complex set of manufacturing and assembly processes. Thus, once the crankcase is made, the geometry of the parts can no longer physically change.
[0007] While it is therefore possible to carry out physical tests on the housing as presented above, i.e. including service arms and suspension arms including pockets, it is difficult to carry out physical tests on any other type of housing because the necessary modifications to the housing entail a heavy manufacturing and assembly process.
[0008] The present invention proposes a simple, effective and economical solution to the need mentioned above. Summary of the invention
[0009] The invention relates to an annular housing, in particular an exhaust housing, for a turbomachine or a turbomachine test bench, this housing extending around an axis and comprising two annular walls, respectively internal and external, extending around each other and around the axis, and radial arms extending between the walls and connecting them together, each of the arms comprising a leading edge, a trailing edge and intrados and extrados faces extending between the leading and trailing edges, each of the arms comprising a radially internal end connected to an external annular surface of the internal wall and a radially external end connected to an internal annular surface of the external wall,
[0010] the housing comprising a plurality of connecting pockets, each of the pockets extending all around at least one of said ends and connecting the intrados and extrados faces as well as the leading and trailing edges to the internal surface of the external wall in the case where the pocket extends all around one of the external ends, and / or to the external surface of the internal wall in the case where the pocket extends all around one of the internal ends.
[0011] According to the invention, at least some of the pockets are mounted removably on the corresponding wall or walls of the housing.
[0012] The removable nature of at least some of the connection pockets allows them to be mounted on and removed from the housing very easily. A change in the geometry of the housing arms (with or without removable pockets) can thus be carried out in a very simplified manner, using only a single housing base (i.e., a single type of housing without the removable pockets), avoiding Thus, the manufacturing processes for new heavy and complex crankcases as described above. The invention therefore makes it possible to physically and rapidly modify the geometry of the crankcase, particularly for the purpose of testing and measuring the actual aerodynamic impacts of different crankcase configurations depending on the presence or absence of pockets on the crankcase arms, especially during turbomachine tests.
[0013] In addition, the invention allows the removable pockets to be mounted and dismounted directly on housings already assembled on turbomachines or test benches, thus avoiding a step of dismantling the housing of the test turbomachine in order to change its configuration and a step of reassembling the modified housing on the turbomachine or test bench.
[0014] The housing according to the invention may comprise one or more of the following features, taken individually or in combination with each other: - some of the pockets are formed from a single piece with the corresponding wall(s). - the arms include service passage arms, each of which includes an internal cavity which opens onto the walls by forming radial orifices, and suspension arms which are radially aligned with suspension brackets located on an external surface of the external wall. - the one-piece pockets are located at the suspension arms, and the removable pockets are located at the service passage arms. - the number of service passage arms is equal to the number of suspension arms and is for example between 4 and 10. - the removable pockets are located exclusively on the outer wall. - the pockets are attached in a removable manner by means of elements screw-nut type fixing, these fixing elements having radial orientations and passing through orifices of the pockets and orifices of the corresponding wall(s). - each of the removable pockets is formed by two pieces which are attached on either side of the end of the arm, respectively on the side of the extrados face and the intrados face of the arm, each of these pieces having an edge conforming to the shape of this intrados or extrados face. - the two pieces of each of the removable pockets are fitted together by at least one male-female system. - each of the removable pockets has an angular range around the axis which is less than or equal to 360° / N, N being the number of arms of the housing. - each of the pockets forms a local deformation of the corresponding wall of the casing. - each of the pockets formed from a single piece defines a hollow on the external surface of the outer wall. - each of the pockets formed from a single piece and each of the removable pockets defines a projection on the internal surface of the external wall and / or on the external surface of the internal wall.
[0015] The invention also relates to a method for testing the aerodynamic performance of an exhaust housing as defined above, this exhaust housing being mounted in a turbomachine test bench, the method comprising the following steps:
[0016] a) analysis of the aerodynamic performance of the crankcase without the removable pockets,
[0017] b) analysis of the aerodynamic performance of the housing with the removable pockets.
[0018] The method according to the invention may comprise one or more of the following features or steps, taken individually or in combination with each other: - in step a), the mounting holes of the pockets provided on the wall(s) are plugged, for example with cement. - in step a), the blocked openings are individually covered by sheets welded onto the wall(s). - in step b), the pockets are fixed to the wall(s) by screw-nut type fixing elements. - step b) is preceded by a step of mounting the pockets and followed by a step of dismantling the pockets, these mounting and dismantling steps being carried out directly in the test bench.
[0019] The invention thus makes it possible to analyze the impact of the presence of the pockets on aerodynamic performance without having to dismantle and then reassemble the casing on the test turbomachine. Brief description of the figures
[0020] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the accompanying drawings in which:
[0021] [Fig.1] [Fig.1] is a partial schematic axial cross-sectional view of a turbomachine;
[0022] [Fig.2] [Fig.2] is a schematic radial cross-sectional view of a turbomachine housing according to the invention;
[0023] [Fig.3] [Fig.3] is a schematic perspective view of a radially external end of a servicing arm of the housing and a sector of this housing;
[0024] [Fig.4] [Fig.4] is a schematic perspective view of the arm of [Fig.3] without removable pocket;
[0025] [Fig. 5a-5b] Figures 5a and 5b are schematic views of one end of an arm of the crankcase suspension seen respectively from the outside and inside of the crankcase;
[0026] [Fig.6] [Fig.6] is a partial schematic perspective view illustrating two parts of a removable pocket intended to be attached to an arm of the housing;
[0027] [Fig.7] [Fig.7] is a partial schematic perspective view of the two parts of [Fig.6] illustrating a system of interlocking the two parts into each other;
[0028] [Fig.8] [Fig.8] is a partial schematic perspective view of a removable pocket mounted on an arm of the housing and its screw-nut type fixing system;
[0029] [Fig.9] [Fig.9] is a view similar to [Fig.8], with the screw-nut type fixing system fixed to the housing;
[0030] [Fig. 10] [Fig. 10] is a view similar to [Fig. 9] from another perspective;
[0031] [Fig. 11] [Fig. 11] is a partial schematic perspective view of an arm of the casing without pockets;
[0032] [Fig. 12] [Fig. 12] is a partial schematic axial cross-sectional view of an external wall of the housing and an arm of the housing;
[0033] [Fig. 13] [Fig. 13] is a partial schematic perspective view of the outer wall of the housing and of an arm of the housing;
[0034] [Fig. 14] [Fig. 14] is a partial schematic axial cross-sectional view of a section of an external wall of the housing; Detailed description of the invention
[0035] Figure 1 shows an aircraft turbomachine 10 extending about an X-axis. The turbomachine 10 comprises, for example:
[0036] - a gas generator 12 comprising a rotating shaft (not shown) around the X-axis,
[0037] - a blower 16 driven by the shaft of the gas generator 12 around the X axis,
[0038] and
[0039] - an annular housing 18 which surrounds the blower 16.
[0040] The gas generator 12 may comprise one or more rotating bodies, and for example a low-pressure body and a high-pressure body. In the example represented, the gas generator 12 comprises a low pressure compressor 20 located downstream of the blower 16 and a high pressure compressor 22 located downstream of the low pressure compressor 20 and axially separated from the latter by an intermediate casing or inter-compressor.
[0041] The turbomachine 10 includes in particular successively, downstream of the high-pressure compressor 22, an annular combustion chamber 24, a high-pressure turbine 26 and a low-pressure turbine 28.
[0042] The intermediate housing includes radial arms 25 which connect the gas generator 10 to the housing 18.
[0043] An airflow Fl enters the turbomachine 10 and passes through the fan 16 before being divided by an annular separator 29 into a first airflow F2 and a second airflow F3. The first radially internal airflow F2, called the primary flow, flows into the gas generator 12 from the low-pressure compressor 20 to the low-pressure turbine 28 in a so-called primary channel. The second radially external airflow F3, called the secondary flow, flows around the gas generator 12, through the arms 25 of the intermediate casing in a so-called secondary channel.
[0044] Throughout this description, the axial direction is the direction of the X-axis, and the radial direction is at every point a direction orthogonal to and passing through the X-axis. The terms "internal" and "external" refer respectively to a relative proximity and a relative distance of an element from the X-axis. Finally, the "upstream" and "downstream" directions are defined with reference to the general direction of gas flow in the primary and secondary sections of the turbomachine, along the axial direction.
[0045] At the downstream end of the gas generator 12, the turbomachine 10 includes an annular casing 30, in particular an exhaust casing. Such an annular casing 30 can also be mounted on a turbomachine test bench. This casing 30 extends around the X-axis and notably comprises two annular walls 31, 32, respectively internal 31 and external 32, extending around each other and around the X-axis. The annular walls 31, 32 define between them a portion of the primary flow.
[0046] As can be seen in particular in [Fig. 2] to 5b, the housing 30 comprises, for example, radial arms 40, 50 which extend between the walls 31, 32 and connect them. Each of the arms 40, 50 has in particular a leading edge 41, 51, a trailing edge 42, 52 and intrados 43, 53 and extrados 44, 54 surfaces extending between the leading edges 41, 51 and trailing edges 42, 52. Each of the arms 40, 50 has a radially internal end 45, 55 connected to an external annular surface 31b of the inner wall 31, and a radially external end 46, 56 connected to an internal annular surface 32a of the outer wall 32.
[0047] The arms 40, 50 include in particular service passage arms 40 and in particular suspension arms 50.
[0048] The number of service passage arms 40 is for example equal to the number of suspension arms 50 and is for example between 4 and 10.
[0049] In the illustrated embodiment, the housing 30 comprises six service arms 40 and six suspension arms 50. The service arms 40 and the suspension arms 50 are, for example, grouped in pairs. The housing 30 therefore comprises three pairs of service arms 40 and three pairs of suspension arms 50, with one pair of service arms 40 adjacent to two pairs of suspension arms 50 and vice versa.
[0050] The servicing arms 40 each include in particular an internal cavity 47 which opens onto the walls 31, 32 by forming radial orifices 48 ([Fig.3]).
[0051] The suspension arms 50 are, for example, radially aligned with at least one suspension bracket 57, in particular two suspension brackets 57, located on an external surface 32b of the external wall 32 and configured to allow the suspension of the turbomachine (Figure 5a). The bracket(s) 57 include, in particular, a mounting hole 58 for suspending the turbomachine.
[0052] The housing 30 also includes a plurality of connecting pockets 60, 70. Each pocket 60, 70 extends, for example, all around one of the ends 45, 55, 46, 56. Each pocket 60, 70 connects, in particular, the intrados 43, 53 and extrados 44, 54 faces as well as the leading edges 41, 51 and trailing edges 42, 52 to the internal surface 32a of the external wall 32 in the case where the pocket 60, 70 extends all around one of the external ends 46, 56 and to the external surface 31b of the internal wall 31 in the case where the pocket 60, 70 extends all around one of the internal ends 45, 56.
[0053] In the illustrated embodiment, the pockets 60, 70 extend exclusively all around the external ends 46, 56, but the invention is of course not limited to this configuration.
[0054] Each of the arms 40, 50 includes, for example, a connecting fillet 120 extending all around one of the ends 45, 55, 46, 56 and connecting the intrados faces 43, 53 and extrados faces 44, 54 as well as the leading edges 41, 51 and trailing edges 42, 52 to the internal surface 32a of the external wall 32 in the case where the connecting fillet 120 extends all around one of the external ends 46, 56 and to the external surface 31b of the internal wall 31 in the case where the connecting fillet extends all around one of the internal ends 45, 56.
[0055] The connecting fillets 120 extend here in particular all around the internal ends 45, 55 but the invention is of course not limited to this configuration.
[0056] The connecting fillets 120 have primarily a mechanical connection function of the arms 40, 50 with the wall(s) 31, 32 of the housing 30, while the recesses 60, 70 have additional functions, such as the function of making space for the positioning of the clevises 57 configured to allow the suspension of the turbomachine 10. The recesses 60, 70 therefore have, in particular, dimensions greater than those of the connecting fillets 120.
[0057] According to the invention, and as illustrated in particular in figures 6 to 10, at least some of the pockets 60, 70, referred to as first pockets 60, are mounted in a removable manner on the corresponding wall or walls 31, 32 of the housing 30, here the outer wall 32. The first pockets 60 are in particular manufactured by additive manufacturing.
[0058] In particular, some of the pockets 60, 70, called second pockets 70 ([Fig.6]), are formed in one piece with the corresponding wall or walls 31, 32, here the external wall 32.
[0059] The pockets 60, 70 include, in particular, a first substantially flat portion 61, 71 which conforms specifically to the wall 31, 32 of the housing 30 on which the pocket 60, 70 is located. The first portion 61, 71 defines, in particular, the periphery of the pocket 60, 70. The pockets 60, 70 include, for example, a second portion 62, 72 connecting the first portion 61, 71 to the arm 40, 50. The second portion 62, 72 conforms to the contour of the arm 40, 50.
[0060] Each of the recesses 60, 70 forms, in particular, a local deformation of the corresponding wall 31, 32 of the housing 30, here the outer wall 32. Each of the recesses 60, 70 defines, in particular, a projection 65, 75 on the outer surface 31b of the inner wall 31 or on the inner surface 31a of the outer wall 32b, as is the case here. The projection 65, 75 is located, in particular, at the level of the second part 62, 72. It projects from the wall 31, 32 on which the recess 60, 70 is located, towards the opposite wall 31, 32.
[0061] The first pockets 60 and the second pockets 70 are in particular of similar or identical shape.
[0062] Each of the second pockets 70 defines for example a hollow 74 (visible in figure 5a), in particular on the external surface 32b of the external wall 32. It is in particular inside this hollow 74 that the screed or screeds 57 are located.
[0063] The first pockets 60 are for example located on the servitude arms 40, in particular on all the servitude arms 40 and especially on the external ends 46 of the servitude arms 40. The first removable pockets 60 are here exclusively located on the external wall 32.
[0064] The second pockets 70 are for example located on the suspension arms 50, in particular on all the suspension arms 50 and especially on the external ends 56 of the suspension arms 50. The second pockets 70 are here exclusively located on the external wall 32.
[0065] The connecting fillets 120 are for example located on the service arms 40, in particular on all the service arms 40 and especially on the internal ends 45 of the service arms 40. The connecting fillets 120 can also be located on the external ends 46 of the service arms 40, they are then covered by the first removable pockets 60 when the latter are mounted on the housing 30.
[0066] The connecting fillets 120 are for example located on the suspension arms 50, in particular on all the suspension arms 50 and especially on the internal ends 55 of the suspension arms 50.
[0067] Each of the removable pockets 60, for example, has an angular extent around the X-axis that is less than or equal to 360° / N, where N is the number of arms 40, 50 of the housing 30, i.e., here less than or equal to 360° / 12 = 30°. In the case where the housing 30 is divided into housing sectors, the number of housing sectors is equal to the number of arms of the housing, and each of the removable pockets 60 therefore extends angularly less around the X-axis than a housing sector on which it is located.
[0068] Each of the first removable pockets 60 is formed in particular by two parts 90, 100, referred to as the first part 90 and the second part 100. Each of these parts, for example, takes the form of a half-shell. The parts 90, 100 are attached, for example, to either side of the end of the arm 40. The first part 90 is attached in particular to the upper surface 44 of the arm 40. The second part 100 is attached in particular to the lower surface 43 of the arm 40. The first part 90 includes an edge 95 conforming to the shape of the upper surface 44. The second part 100 includes an edge 105 conforming to the shape of the lower surface 43.
[0069] The two parts 90, 100 of each of the removable pockets 60 are, for example, fitted together by at least one male-female system 110, visible in particular in Figures 6 and 7. The first part 90 includes, for example, a female part 111, in particular an orifice 112. The second part 100 includes, for example, a male part 113, in particular a centering pin 114. The female parts 111 and male parts 113 are configured to center the second part 100 relative to the first part 90 and to allow correct positioning of the first part 90 with respect to the second part 100, in particular for their attachment to the housing 30.
[0070] The first removable pockets 60 are fixed in a removable manner, in particular by fastening elements 80 of the screw-nut type, visible in particular in Figures 8 to 10. The fastening elements 80 have, in particular, orientations radial and pass through, for example, orifices 63 of removable pockets 60 and orifices 33 of the corresponding wall(s) 31, 32. The fasteners 80 include, for example, screws 81, nuts 82 and washers 83.
[0071] The invention also relates to a method for testing the aerodynamic performance of the crankcase 30 as defined above, this exhaust crankcase 30 being mounted in a turbomachine test bench, the method comprising the following steps:
[0072] a) analysis of the aerodynamic performance of the housing 30 without the first removable pockets 60,
[0073] b) analysis of the aerodynamic performance of the housing 30 with the first removable pockets 60.
[0074] In particular, in step a), the mounting holes 33 (visible in [Fig. 11]) for the first removable pockets 60 provided on the wall(s) 31, 32 are plugged, for example with cement 34 (visible in [Fig. 12]). The holes 33 are, in particular, drilled in the wall(s) 31, 32. The cement 34 fills, for example, the entire opening of each hole 33.
[0075] In step a), and as can be seen in particular in figures 13 and 14, the plugged orifices 33 are for example individually covered by sheets (or shims) 35 welded onto the wall(s) 31, 32 (here on the external wall 32).
[0076] The plates 35 notably prevent potential loss of cement 34 into the turbomachine's flow during testing. The plates 35 can be welded to both sides of the wall 32 as illustrated in [Fig. 14], that is, to the external surface 32b and to the internal surface 32a of the wall 32, so as to cover the plugged orifices 33 on both sides. Each orifice 33 thus corresponds to two plates 35.
[0077] In step b), the first removable pockets 60 are in particular fixed to the wall(s) 31, 32 by the fixing elements 80 as explained previously.
[0078] Step b) is, for example, preceded by a step of assembling the first removable pockets 60 and followed by a step of disassembling the first removable pockets 60. In order to assemble the first removable pockets 60, it is necessary, in particular, to remove the sheets 35 and the cement 34 to free the mounting holes 33 for the first removable pockets 60. During this step, the sheets 35 are, for example, removed by breaking the weld points, and the cement 34 is removed, in particular, by tapping it.
[0079] Each first removable pocket 60 is in particular mounted on the housing 30 by a simple and quick process, that is to say by positioning the first part 90 in relation to the second part 100 all around the servicing arm 40 using in particular the male female system 110 and then fixing the first part 90 and the second part 100 on the housing 30 using for example the fixing system 80. The disassembly procedure for each first removable pocket 60 simply involves performing the steps in reverse order.
[0080] These assembly and disassembly steps are in particular carried out directly in the test bench, that is to say in particular without disassembly and removal of the housing 30 of the turbomachine or of the test bench.
Claims
Demands
1. An annular housing (30), particularly an exhaust housing, for a turbomachine or a turbomachine test bench, said housing (30) extending about an axis (A) and comprising two annular walls (31, 32), respectively inner (31) and outer (32), extending around each other and around the axis (A), and radial arms (40, 50) extending between the walls (31, 32) and connecting them, each of the arms (40, 50) comprising a leading edge (41, 51), a trailing edge (42, 52) and intrados (43, 53) and extrados (44, 54) faces extending between the leading (41, 51) and trailing (42, 52) edges, each of the arms (40, 50) comprising a radially internal (45, 55) connected to an external annular surface (31b) of the internal wall (31) and a radially external end (46, 56) connected to an internal annular surface (32a) of the external wall (32), the housing (30) comprising a plurality of connecting pockets (60, 70),each of the pockets (60, 70) extending all around at least one of said ends (45, 55, 46, 56) and connecting the intrados (43, 53) and extrados (44, 54) faces as well as the leading (41, 51) and trailing (42, 52) edges to the inner surface (32a) of the outer wall (32) in the case where the pocket (60, 70) extends all around one of the outer ends (46, 56), and / or to the outer surface (31b) of the inner wall (31) in the case where the pocket (60, 70) extends all around one of the inner ends (45, 56), characterized in that at least some (60) of the pockets (60, 70) are removably fixed by fastening elements (80) of the screw-nut type on the corresponding wall(s) (31, 32) of the housing (30), the fastening elements (80) having radial orientations and passing through openings (63) in the removable pockets (60) and openings (33) in the corresponding wall(s) (31, 32).
2. Carter (30) according to claim 1, wherein further (70) of the pockets (60, 70) are formed in one piece with the corresponding wall(s) (31, 32).
3. A housing (30) according to claim 1 or 2, wherein the arms (40, 50) comprise service passage arms (40), each comprising an internal cavity (47) opening onto the walls (31, 32) by forming radial ports (48), and service passage arms suspension (50) which are radially aligned with suspension shackles (57) located on an external surface (32b) of the external wall (32).
4. Carter (30) according to claims 2 and 3, wherein the one-piece pockets (70) are located at the suspension arms (50), and the removable pockets (60) are located at the service passage arms (40).
5. Carter (30) according to claim 3 or 4, wherein the number of servicing passage arms (40) is equal to the number of suspension arms (50) and is for example between 4 and 10.
6. Carter (30) according to any one of the preceding claims, wherein the removable pockets (60) are exclusively located on the outer wall (32).
7. Carter (30) according to any one of the preceding claims, wherein each of the removable pockets (60) is formed by two pieces (90, 100) which are attached on either side of the end of the arm (40, 50), respectively on the side of the extrados face (44, 54) and the intrados face (43, 53) of the arm (40, 50), each of these pieces (90, 100) having an edge (95, 105) conforming to the shape of this intrados face (43, 53) or extrados face (44, 54).
8. Carter (30) according to claim 7, wherein the two pieces (90, 100) of each of the removable pockets (60) are fitted together by at least one male-female system (110).
9. Housing (30) according to any one of the preceding claims, wherein each of the removable pockets (60) has an angular extent around the axis (A) which is less than or equal to 360° / N, N being the number of arms (40, 50) of the housing (30).
10. Method for testing the aerodynamic performance of an exhaust housing (30) according to any one of the preceding claims, said exhaust housing (30) being mounted in a turbomachine test bench, the method comprising the following steps: a) analysis of the aerodynamic performance of the housing (30) without the removable pockets (60), b) analysis of the aerodynamic performance of the housing (30) with the removable pockets (60).
11. A method according to claim 10, wherein, in step a), mounting holes (33) for the removable pockets (60) are provided
12.
13.
14. on the wall(s) (31, 32) are blocked, for example with cement. Method according to claim 11, wherein, in step a), the plugged orifices (33) are individually covered by sheets welded (35) onto the wall(s) (31, 32). A method according to any one of claims 10 to 12, wherein, in step b), the removable pockets (60) are fixed to the wall(s) (31, 32) by fixing elements (80) of the screw-nut type. A method according to any one of claims 10 to 13, wherein step b) is preceded by a step of mounting the removable pockets (60) and followed by a step of dismounting the removable pockets (60), these mounting and dismounting steps being carried out directly in the test bench.