FR3115879A1 - AIRCRAFT TURBOMACHINE TEST BENCH AND METHOD FOR REDUCING THE CROSS SECTION OF A FLOW FLOW VEIN IN THIS TEST BENCH - Google Patents

Abstract

Aircraft turbomachine test bench (2), comprising: - a device configured to generate a gas flow (20) in an annular vein (16) which extends along an axis (X) and which is internally delimited by an aerodynamic outer annular surface (17) of a casing (15), characterized in that it further comprises panels (50) comprising first removable panels (24), the first panels (24) being mounted around said casing (15) and having a first outer annular aerodynamic surface (29) intended to at least partially cover the outer surface (17) of the casing (15) and to reduce the cross section (25) of the vein (16 ) with respect to said axis (X). Figure for abstract: Figure 3

Description

AIRCRAFT TURBOMACHINE TEST BENCH AND METHOD FOR REDUCING THE CROSS SECTION OF A FLOW FLOW VEIN IN THIS TEST BENCH

Technical field of the invention

The present invention relates to a test bench for an aircraft turbomachine and a method for reducing the cross section of a flow path of a stream in such a test bench.

Technical background

A propulsion assembly comprises for example a dual-flow turbomachine integrated in a nacelle. The turbomachine generally comprises, from upstream to downstream in the direction of fluid flow through the turbomachine, at least one fan and one gas generator. The gas generator comprises for example one or more compressor stages, low pressure and high pressure, a combustion chamber, one or more turbine stages, high pressure then low pressure.

The blower, located upstream of the gas generator, generates an air flow which is then divided by a flow separator (or splitter), into a primary air flow and a secondary air flow circulating from upstream downstream. More precisely, the primary flow flows in an annular primary stream of the gas generator and the secondary air flow flows in an annular secondary stream. The secondary vein is delimited radially between the external annular surface of the gas generator, also called "IFD" whose acronym is defined by the Anglo-Saxon term Inner Fan Duct , that is to say internal blower vein, and the internal surface of a fan casing, also called “OFD” whose acronym is defined by the Anglo-Saxon term Outer Fan Duct , that is to say external fan duct and participates in a predominant way in the thrust provided by the propulsion unit. By convention, in the present application, the terms “upstream” and “downstream” are defined with respect to the direction of circulation of the gases in the propulsion assembly when the latter operates in “propeller” mode. Similarly, by convention in the present application, the terms “internal” and “external” are defined radially with respect to the longitudinal axis of the turbomachine, which is in particular the axis of rotation of the rotors of the compressors and of the turbines.

The profile of the internal surface of the secondary stream is not optimized from a turbomachine efficiency point of view. Indeed, this internal surface comprises in particular a portion, downstream of the annular flow separator, which has a larger cross-section than those of the other portions. However, this local increase in the cross-section generates significant pressure drops in the secondary flow, directly impacting the level of thrust achieved by the turbomachine.

The object of the present invention is in particular to solve all or part of the aforementioned problems.

The invention proposes for this purpose an aircraft turbomachine test bed, comprising:

- a device configured to generate a flow of gas in an annular vein which extends along an axis and which is internally delimited by an aerodynamic external annular surface of a casing.

According to the invention, the test bench further comprises panels comprising first removable panels, the first panels being mounted around said casing and having a first aerodynamic external annular surface intended to cover at least part of the external surface of the casing and to reduce the cross-section of the vein with respect to said axis.

The invention thus provides for adding first removable panels on the outer surface of the casing, in particular at the level of the portion of the vein which has a larger cross-section.

These first panels can be positioned on test benches, development turbomachines or during flight tests and thus make it possible to reduce the cross-section of the test section. It will then be possible to optimize the thrust of the turbomachines manufactured on the basis of the veins tested.

Thanks to the invention, it is also possible to temporarily modify the section of the vein tested for another mode of operation by adding or removing the first removable panels.

In addition, the panels of the invention can be integrated without modification or disassembly of current test benches, thus making it possible to carry out tests quickly.

The test bench, according to the invention, may include one or more of the characteristics below, taken separately with each other or in combination with each other:

- at least some of the first panels comprise a flat wall comprising the first aerodynamic surface and a second opposite surface comprising protruding elements configured to bear on said casing;

- it comprises straightening arms extending in the vein, said first panels being located just downstream of at least some of these straightening arms;

- The panels comprise second removable panels mounted in the upstream extension of the first panels flush with the latter;

- the panels are fixed by screws;

- seals are fitted between said panels;

- the panels are made of plastic material, for example ULTEM®;

- the device comprises a blower configured to generate the flow of gas, part of which forms the flow which flows in said vein, and another part of which forms another flow of gas which flows in another vein inside said housing;

- said casing extends axially from an upstream end located at the level of an annular separator of said flows to a downstream end located at the level of an ejection nozzle, said casing comprising a middle portion of larger diameter around which are mounted said first panels.

The present invention also relates to a method for reducing the cross-section of a flow path of a stream in a test bench as described above, in which it comprises a step of mounting the panels around said casing.

The method further comprises a preliminary step of producing said plastic panels by additive manufacturing.

The method thus makes it possible to manufacture the panels easily and quickly.

In addition, the manufacturing process of the panels makes it possible to resist the mechanical stresses to which they are subjected.

Brief description of figures

Other characteristics and advantages of the invention will appear during the reading of the detailed description which will follow for the understanding of which reference will be made to the appended drawings in which:

there is a schematic half view, in longitudinal section, of a test bench comprising a turbomachine;

there is a partial schematic view, in longitudinal section, of the test bench of the ;

there is a schematic perspective view of a casing of a test bench provided with first removable panels according to the invention;

there is a schematic view in longitudinal section of panels mounted on a test bench according to the invention; And

there is a schematic detailed perspective view of the panels of the .

Detailed description of the invention

On the a test bed 1 comprising a turbomachine 2 with aircraft or test turbofan is shown. In the example illustrated, the test bench 1 comprises the whole of a turbine engine but according to an alternative of the invention not represented, the test bench 1 comprises only part of the turbine engine, that is that is to say one or more modules of the turbomachine.

The test bench 1 comprises in particular a device configured to generate a flow of gas 20. This device is for example a ducted fan 4.

The turbomachine is integrated in a casing 3, in particular a fan casing, and comprises downstream of the fan 4, a gas generator 5. The gas generator 5 extends along an axis X, longitudinal to the turbomachine 2. The generator 5 comprises several compressor stages, low pressure 6 and high pressure 7, a combustion chamber 8, and several turbine stages , high pressure 9 then low pressure 10. The gas generator 5 comprises a casing 15 having an outer surface 17 and an inner surface 14 extending one around the other and meeting at the level of a spout 19. The casing 15 has an axis of revolution coincident with the axis X of the turbomachine 2, which is in particular the axis of rotation of the rotors of the fan 4, of the compressors 6, 7 and of the turbines 9, 10.

The turbomachine 2 further comprises, on the one hand, an annular main stream 12 of the gas generator 5 delimited radially between a casing 13 of the movable rotors of the turbomachine 2 and the internal surface 14 of the casing 15. The turbomachine 2 comprises on the other hand, an annular vein 16, called secondary vein 16, around the generator 5, delimited radially between an internal surface 18, also called "IFD" whose acronym is defined by the Anglo-Saxon term Inner Fan Duct , and a surface external 11 of the secondary vein 16, also called "OFD" whose acronym is defined by the Anglo-Saxon term Outer Fan Duct . The inner surface 18 of the secondary stream 16 comprises the outer surface 17 of the casing 15. The outer surface 11 of the secondary stream 16 comprises the inner surface of the casing 3 of the fan 4. The term “radial” is defined with respect to a axis substantially perpendicular to the longitudinal axis X of the turbomachine 2. In general, the terms “upstream” and “downstream” are defined with respect to the circulation of the stream 20, parallel to the longitudinal axis X.

As shown in Figures 1 and 2, the fan 4 is located upstream of the gas generator 5 and configured to generate a flow of gas 20. This flow of gas 20, flowing from upstream to downstream, is divided by the nozzle 19 separating the main stream 12 of the generator 5 and the secondary stream 16. Thus, part of the stream 20 forms a primary stream 21 (or other stream 21) and flows into the main stream 12 (or other stream 12) at inside the gas generator 5 and another part of the flow 20 forms a secondary flow 22 and flows in the secondary vein 16 around the gas generator 5. The spout 19 is also called an annular separator 19 of the flows. The secondary flow 22 participates in a preponderant manner in the thrust provided by the turbomachine 2.

According to the invention, the test bench 1 further comprises panels 50 comprising first removable panels 24. The latter are mounted around the casing 15 and have a first aerodynamic outer annular surface 29 intended to cover at least part of the surface. 17 external of the housing 15 and to reduce the cross section 25 of the secondary vein 16 with respect to the axis X.

The first removable panels 24 thus have an internal profile which makes it possible to be mounted around the casing 15, at the level of the portion of the secondary vein 16 which has a larger cross section so as to reduce this cross section.

As shown on the , the casing 15 extends axially from an upstream end located at the level of the annular separator 19 of the flows 20 to a downstream end located at the level of an ejection nozzle 23 of the primary flow 21. When the turbomachine 2 does not is not equipped with the first panels 24, the outer surface 11 of the fan casing 3 and the outer surface 17 of the casing 15 are substantially parallel, except at the level of a middle portion 28 of the casing 15 having a larger diameter, which causes a larger cross-section 25 of the secondary vein 16 at the level of this middle portion 28. The first removable panels 24 are then mounted according to the invention around this middle portion 28 so that the cross-section 25 of the secondary vein 16 is modified locally on this middle portion. In other words, the radial thickness of the first panels 24 makes it possible to modify, and for example reduce, the cross-section 25 of the secondary vein 16 with respect to the axis X at the level of the middle portion 28.

Thus, once the first removable panels 24 are positioned on the casing 15, the internal surface 18 of the secondary vein 16 is composed of the first external annular surface 29 of the first panels 24 at the level of the middle portion 28 and the external surface 17 of the casing 15 where the first panels 24 are not positioned.

In FIGS. 3 and 4, the turbomachine further comprises straightening arms 30 which extend radially through the secondary vein 16. These straightening arms 30 notably comprise two walls, which extend axially and which are interconnected. The term "axially" means parallel to the longitudinal axis X. The set of arms 30 consists of several axially short arms 33 and axially long arms, in particular two axially long arms, respectively an arm 31 and an arm 32, diametrically opposites. More precisely, the long arms 31, 32 comprise an extension 34 downstream parallel to the axis X. The extension 34 has a length Lb, thus allowing the long arms 31, 32 to extend downstream over more than half the length L of the casing 15, that is to say to have a length which is greater than half the longitudinal length L of the casing 15. The short arms 33 are placed between the long arms 31, 32 along the circumferential direction. The first panels 24 are located just downstream of the short arms 33 and are placed circumferentially between the extensions 34 of the long arms 31, 32. The turbomachine comprises for example four first panels 24 arranged circumferentially in pairs, each group of two first panels 24 being disposed on either side of the arms 31, 32 long. The optimization of the vein is therefore carried out here at the level of an area of the test bed located between the extensions 34. Alternatively, another area of the test bed could be optimized in the same way. The first panels 24 would then be positioned on another zone of the test bed than that comprising the extensions 34.

As shown on the , some of the first panels 24 have a substantially planar wall comprising the first aerodynamic surface 29 and a second surface 26, opposite the first surface 29. The second surface 26 comprises projecting elements 36 configured to bear on the casing 15, in particular on the outer surface 17 of the casing 15. In addition, the first panels 24 may have ribs 27 in order to increase their mechanical strength. These ribs 27 can form projecting elements 36 bearing on the casing 15.

The second surface 26 of the first panels 24, which corresponds to the internal profile of the first panel 24, is thus manufactured to be able to be positioned on the external surface 17 of the casing 15, in particular via the projecting elements 36. The first surface 29 , which corresponds to the outer profile of the panel 24, then becomes part of the surface 18 delimiting the vein 16 secondary.

The first panels 24 each include a downstream edge 24b at which the first panels 24 are flush with the outer surface 17 of the casing 15.

The first panels 24 also comprise an upstream edge 24a at the level of which the first panels 24 are flush with the outer surface 17 of the casing 15 so as to make the cross-section 25 of the secondary stream 16 constant (embodiment not shown). Alternatively and as shown in Figures 4 and 5, the panels 50 may also include second panels 43, in particular removable and for example mounted around the casing 15 in particular in the upstream extension of the first panels 24.

The second panels 43 are for example located between the straightening arms 30. These second panels 43 are located downstream of the separator 19 of the flows 20 and just upstream of the first panels 24. The second panels 43 extend circumferentially around the casing 15, each second panel 43 occupying the entire surface of the casing 15 which is located between the arms 30 rectifiers. There are for example as many first panels 24 as second panels 43. Each second panel 43 is then located in the extension of a first panel 24. The second panels 43 are positioned so as to allow a flush with the first panels 24 so as to thus improve the aerodynamics of the profile of the secondary vein 16. More specifically, downstream edges 43b of the second panels 43 cover the upstream edges 24a of the first panels 24 so as to guarantee continuity between the first panels 24 and the second panels 43.

The panels 50 and in particular the first panels 24 are fixed by screws 40 in the fixings 39. The fixings 39 correspond in particular to through holes and nuts available on the external surface 17 of the casing 15. Indeed, the casing 15 of the generator not being disassembled during assembly of the first panels 24, all of its fixings 39 remain available.

The first panels 24 are for example fixed to the second panels 43 at the level of the upstream edges 24a of the first panels 24 and the downstream edges 43b of the second panels 43, in particular by means of screws.

Seals 41 are for example mounted between the panels 50 and in particular between the first panels 24 so that the secondary stream 16 obtained is sealed and has a continuous profile. More precisely, the seals 41 make it possible to harmonize the surface 18 of the secondary stream and thus its aerodynamic profile. The seals 41 can also be made/arranged between the second panels 43 and in particular between the first panels 24 and the second panels 43. The seals 41 are in particular made of silicone, for example RTV silicone, the he acronym “RTV” designates the Anglo-Saxon terms Room Temperature Vulcanizing. The use of this silicone makes it possible to fill the interstices between the panels 50, in particular the first panels 24, and any defects on the profile of the internal annular surface 18. The profile defects are in particular characterized by the presence of steps between the first panels 24, which generated, without the presence of seals 41, pressure drops in the secondary flow 22.

50 panels, including early 24 panels and in particular the second panels 43 are made of plastic material, for example a thermoplastic. An example of a thermoplastic is a resin based on an amorphous thermoplastic polyetherimide (PEI) known by the name ULTEM®. Indeed, the temperature of the air in the secondary vein 16 can reach more than 100ºC, in particular a temperature lower than 120ºC. ULTEM® plastic is a material resistant to 120ºC, that is to say resistant to the thermal environment of the secondary vein 16. The use of ULTEM® for the manufacture of the first panels 24 thus makes it possible to avoid the degradation of the parts making up the panels 50 thanks to its resistance to thermal and mechanical stresses.

The invention also relates to a method for reducing the cross-section 25 of the secondary flow path 16 of the secondary flow 22 in the turbomachine 2, as described above. The method includes a step of mounting the panels 50 and in particular the first removable panels 24 around the casing 15. The method can also include a step of mounting the second panels 43 around the casing 15.

The first removable panels 24 and possibly the second panels 43 thus make it possible to reduce the cross-section 25 of the secondary stream 16 so as to optimize its efficiency and maximize the thrust of the turbomachine. In addition, the turbomachines 2 are mass-produced and are normally optimized for one mode of operation, for example to fly at a low cruising altitude. By way of example, it is possible to temporarily modify the section 25 of the secondary vein 16 in order to optimize the thrust provided by the propulsion assembly for another mode of operation by positioning or removing the first removable panels 24 and possibly the second panels 43.

The method further comprises a preliminary step of producing the panels 50, in particular the first panels 24 and in particular the second panels 43, in plastic material by additive manufacturing. Additive manufacturing is a 3D printing process. This process makes it possible to manufacture complex parts directly from the 3D model, which makes it particularly suitable for the manufacture of the first panels 24 which must have a complex shape profile in order to adapt to the complexity of the profile of the external surface 17 crankcase 15.

Thanks to this process, it is also not necessary to produce a manufacturing range, and the number of operators required for manufacturing is reduced. Panel manufacturing times are therefore very short. With the aim of carrying out tests quickly to characterize the behavior of the aerodynamic internal surface 18 of the section 16, the panels 50 and in particular the first panels 24 can be made available quickly on the test bench. In addition, it is not necessary to dismantle the outer surface 17 of the casing already in place on the turbomachine to integrate the first panels 24, thus making it possible to carry out the tests in very short times.

The test bench according to the invention has been described as comprising the whole of a turbomachine, but the invention indeed relates to a test bench comprising only one or more modules of a turbomachine. In the latter case, the fan of the turbomachine can be replaced for example by the device configured to generate a flow of gas, and the gas generator can in particular be replaced by an electric motor.

Thus, the panels 50 of the invention can be applied to any circular aerodynamic vein.

Claims (11)

Aircraft turbomachine test bench (2), comprising:
- a device configured to generate a flow of gas (20) in an annular vein (16) which extends along an axis (X) and which is internally delimited by an aerodynamic external annular surface (17) of a housing (15),
characterized in that it further comprises panels (50) including removable first panels (24), the first panels (24) being mounted around said housing (15) and having a first outer annular airfoil surface (29) for at least partially covering the outer surface (17) of the casing (15) and reducing the cross section (25) of the vein (16) with respect to said axis (X). A test rig (2) according to claim 1, wherein at least some of the first panels (24) comprise a planar wall comprising the first aerodynamic surface (29) and an opposing second surface (26) comprising protrusions configured to rest on said casing (15). Test bench (2) according to one of the preceding claims, in which it comprises straightening arms (30) extending in the vein (16), the said first panels (24) being located just downstream of at least some of these straightening arms (30). Test bench (2) according to one of the preceding claims, in which the panels (50) comprise second removable panels (43) mounted in the upstream extension of the first panels (24) flush with the latter (24) . Test bench (2) according to one of the preceding claims, in which the panels (50) are fixed by screws (40). Test bench (2) according to one of the preceding claims, in which seals (41) are arranged between said panels (50). Test bench (2) according to one of the preceding claims, in which the panels (50) are made of plastic material, for example ULTEM®. Test bench (2) according to one of the preceding claims, in which the device comprises a fan (4) configured to generate the flow of gas (20), part of which forms the flow (22) which flows in said vein (16), and another part of which forms another gas flow (21) which flows in another vein (12) inside said casing (15). Test bench (2) according to the preceding claim, in which the said casing (15) extends axially from an upstream end located at the level of an annular separator (19) of the said streams (21, 22) to an end downstream located at the level of an ejection nozzle (23), said casing (15) comprising a middle portion (28) of larger diameter around which said first panels (24) are mounted. Method for reducing the cross section (25) of a flow path (16) of a flow (22) in a test bench (2) according to one of the preceding claims, in which it comprises a step mounting panels (50) around said casing (15). Method according to the preceding claim, in which it comprises a preliminary step of producing said panels (50) in plastic material by additive manufacturing.