FR3117548A1 - MAIN AIR FLOW DRIVE DEVICE FOR AN AIRCRAFT TURBOMACHINE - Google Patents

Abstract

Device (110) for driving a main air flow (F1) for an aircraft turbine engine (22), this device comprising: - a first duct (112) for flowing a main air flow (F1), - a plurality of ejectors (114) of a secondary air flow (F2) located inside the first duct (112) and configured to eject a secondary air flow (F2) and force the flow of the main air flow (F1) in this first pipe (112), and - a second exhaust pipe (116) located at the outlet of the ejectors (114) and connected to the first pipe (112), characterized in that said second conduit (116) comprises: - a tubular endpiece (116a) connected to the first conduit (112), and - a central body (116b) located inside the endpiece (116a) and connected to this tip by connecting arms (116c). Figure for abstract: Figure 5

Description

MAIN AIR FLOW DRIVE DEVICE FOR AN AIRCRAFT TURBOMACHINE

Technical field of the invention

The present invention relates to the exhaust of a device for driving a main air flow by a high-energy secondary fluid. This training system is applied to aircraft turbine engines.

Technical background

It is known to drive a main air flow via a secondary air flow with more energy than the main air flow. A device for driving a main air flow of this type conventionally comprises a flow pipe for a main air flow and ejectors for a secondary air flow located inside the pipe. and configured to eject the secondary air stream which will force the flow of the main air stream by viscous entrainment in this duct.

Ejectors, also called jet horns, are supplied with high pressure and/or high temperature air. The difference in momentum between the two flows generates viscous entrainment of the main air flow at lower pressure and therefore its suction into the pipe. The following prior art documents describe several applications of this type of device: WO-A1-2014/060656, FR-A1-3 011 583, FR-A1-3 022 588 and FR-A1-3 087 239.

One of the problems with this type of device concerns the control of turbulence and pressure drops at the outlet of the ejectors, which reduce the performance of the device and may require it to be oversized for a given application. This then affects the pressure balance between the upstream of the primary flow, the secondary flow and the downstream of the system exhaust.

When the pressure upstream of the device decreases and/or the pressure drops and turbulence are too high at the outlet of the ejectors, the Venturi effect generated loses its effectiveness. At a certain threshold of pressure losses upstream of the system generated by the intake device, the main air flow is reversed and the secondary air flow is re-aspirated upstream, which can damage the parts in this area.

The invention proposes an improvement to this technology through the exhaust of the system which has the effect of better channeling the jets of the ejectors making it possible to reduce turbulence and pressure drops at the outlet of the latter, thus making it more robust to losses. pressure upstream of the system.

The invention relates to a device for driving a main air flow for an aircraft turbine engine, this device comprising:

- a first flow pipe for a main air flow, this first pipe having a main axis,

- a plurality of ejectors of a secondary air flow located inside the first duct and configured to eject a secondary air flow and force the flow of the main air flow in this first duct, said ejectors being distributed around said main axis, and

- a second exhaust pipe located at the outlet of the ejectors and connected to the first pipe,

characterized in that said second conduit comprises:

- a tubular endpiece configured to be connected to the first pipe, and

- a central body located inside the end piece and connected to this end piece by connecting arms, said central body having an aerodynamic profile and comprising a leading edge, said central body defining with said end piece a peripheral vein of flow of the air mixture of the main and secondary flows, which is divided by said central body and said arms into at least two parts.

The inventors have demonstrated that the center of the exhaust duct is conducive to aerodynamic recirculation and re-aspiration of fluid leading, after a certain pressure loss threshold upstream of the system, to a reversal of the flows.

The central body is configured to reduce turbulence and pressure drops in this area. The combination of the central body and the end piece makes it possible to define a vein of optimal shape and dimensions for the flow of flows, by limiting turbulence and pressure drops. The arms connect the central body to the mouthpiece and divide this vein into several portions of flow flow. The central body and the arms advantageously have profiles making it possible to orient the wakes of the ejectors.

The device according to the invention may comprise one or more of the following characteristics, taken separately from each other, or in combination with each other:

- the peripheral vein is divided by said central body and said arms into at least two parts having identical passage cross-sections;

- the arms have a substantially radial orientation with respect to said main axis and their number is between 2 (or even 1) and K, K being the number of ejectors;

• said leading edge is located upstream of the ejector outlets;
• the central body has a thickness in axial section which increases from said leading edge to the level of the outlets of the ejectors then which decreases from the outlets of the ejectors to a trailing edge of this body;
• said leading edge is aligned with said main axis;
• the end piece comprises an external annular flange for connection to the first pipe, this flange being located axially at a distance from said leading edge so that the latter can be engaged in said first pipe;
• the end piece comprises an external annular flange engaged in said first pipe, this flange comprising an external peripheral edge comprising notches each configured to receive a base of one of said ejectors;
• said second pipe may have a bent shape;
• said second conduit is formed in one piece, preferably of metal.

The invention further relates to a turbine engine, in particular for an aircraft, comprising a device as described above.

Advantageously, the turbomachine comprises, from upstream to downstream, in the direction of gas flow in the turbomachine, an air inlet, at least one compressor, a combustion chamber, at least one turbine and an exhaust, said inlet air being equipped with a particle trap which is connected to said device.

Brief description of figures

Other characteristics and advantages will emerge from the following description of a non-limiting embodiment of the invention with reference to the appended drawings in which:

there is a very schematic view of a device for driving a main air flow for an aircraft turbine engine;

there is a diagrammatic view in axial section of an aircraft turbine engine equipped with a device of the type of that of the ;

there is a schematic view in perspective and in axial section of a device for driving a main air flow, according to the technique prior to the present invention;

there is a schematic perspective view of a device for driving a main air flow, according to one embodiment of the invention;

there is a sectional view along line AA of the ;

there is a sectional view along the line BB of the ;

there is a schematic perspective view of the second conduit of the device of the ;

there is another schematic perspective view of the second conduit of the device of the ;

there is another schematic perspective view of the second conduit of the device of the ;

there is a schematic perspective view of a device for driving a main air flow, according to a variant embodiment of the invention;

there is a sectional view along line AA of the ;

there is a schematic perspective view of a second conduit of the device of the ;

there is another schematic perspective view of the second conduit of the device of the ;

there is another schematic perspective view of the second conduit of the device of the .

Detailed description of the invention

There is a very schematic representation of a device 10 for driving a main air flow F1 by a secondary air flow F2 for an aircraft turbine engine.

The device 10 comprises:

- a first pipe 12 for the flow of the main air flow F1, this first pipe having a main axis A,

- a plurality of ejectors 14 of the secondary air flow F2, which are located inside the first duct 12 and configured to eject the secondary air flow F2 and force the flow of the main air flow F1 in the first conduit 12, and

- a second exhaust pipe 16 located at the outlet of the ejectors 14 and connected to the first pipe 12.

The device 10 is generally connected upstream (by reference to the flow of the flows F1, F2 in the device 10) to an enclosure 18, such as an enclosure to be purged or an enclosure forming a particle trap, of the turbomachine of aircraft.

The device 10 is generally connected downstream to the outside 20 of the turbine engine.

The first pipe 12 has a generally elongated and rectilinear shape, although this is not limiting. Similarly, the second pipe 16 has a generally elongated and rectilinear shape but can be bent as a variant.

The ejectors 14 are connected to a high pressure and/or high temperature air supply source and generate a secondary air flow F2 in the first pipe 12 which drives by viscous friction a flow of the main flow F1 in the pipe 12 The flows F1, F2 then flow in the second pipe 16 to the outside 20 of the turbomachine.

The technology of this type of ejector or jet horn is well known to those skilled in the art and therefore does not need to be detailed.

There illustrates an example of installation of a device 10 in a turbomachine 22 here of an aircraft of the helicopter type.

The turbomachine 22 conventionally comprises, from upstream to downstream, an air inlet 24, at least one compressor 26, a combustion chamber 28, at least one turbine 30 and an exhaust 31.

The air inlet 24 has an annular shape and comprises an upstream portion 24a of frustoconical shape which is flared downstream, and a downstream portion 24b of frustoconical shape which is on the contrary flared towards the upstream. In other words, the air inlet 24 has, at the junction between these portions 24a, 24b, a maximum diameter.

The flow of air F0 which enters the air inlet 24 therefore first flows radially from the inside outwards in the first portion 24a of the air inlet 24, then radially from the inside. outside to the inside in the second portion 24b and to the compressor 26. During the flow of the air flow F0 in the first portion 24a, the particles potentially present in this air flow are conveyed by inertia in the enclosure 18 which is connected to the outer periphery of the air inlet 24.

The device 10 extends along and on one side of the turbine engine 22. In the example shown, the first pipe 12 extends from the enclosure 18 and the air inlet 24 to the exhaust 31 The ejectors 14 are mounted in the first duct 12 at the level of the turbine 30 and are supplied with air under pressure and/or temperature taken directly from the turbine 30 by suitable taking-off means 32. The second pipe 16 extends downstream of the first pipe 12 and of the turbine 30 and for example at the level of an exhaust 31 for example in the form of an exhaust gas outlet nozzle.

Device 10 of the is therefore associated with an enclosure 18 and an air inlet 24a forming a particle trap at the inlet of the turbomachine 22.

There illustrates a device 10 according to the prior art. It can be seen that the second conduit 16 is formed by a single tubular wall. It is also noted that the ejectors 14 are distributed around the axis A of the first pipe 12. This technology is not satisfactory because of the turbulence and pressure drops which appear in operation at the outlet of the ejectors, as mentioned in this which precedes making it very sensitive to pressure losses upstream of the system leading to a re-suction of the primary and secondary flows.

The present invention proposes a solution to this problem with a device 110, one embodiment of which is represented in FIGS. 4 to 9.

Device 110 includes

- a first pipe 112 for the flow of the main air flow F1, this first pipe 112 having a main axis A,

- a plurality of ejectors 114 of the secondary air flow F2, which are located inside the first duct 112 and configured to eject the secondary air flow F2 and force the flow of the main air flow F1 in the first conduit 112, and

- a second exhaust pipe 116 located at the outlet of the ejectors 114 and connected to the first pipe 112.

The first pipe 112 has a generally tubular shape and can be straight or bent. It comprises a longitudinal end equipped with an external annular fixing flange 134.

The ejectors 114 are located in the first pipe 112, close to the flange 134, and each have a generally bent shape in the example shown. Each ejector 114 is tubular and comprises an end 114a connected to a through hole 136 of the pipe 112, and an opposite end 114b which is narrowed to form a nozzle and which is oriented in a direction parallel to the axis A and towards the flange 134 ( ).

The orifices 136 open into an annular manifold 138 which is mounted around the pipe 112 and which is connected to sampling means 132 ( ) comparable to the sampling means 32 mentioned above.

The second pipe 116 essentially comprises three parts, namely:

- a tubular connector 116a configured to be connected to the first conduit 112, and

- a central body 116b located inside the end piece 116a, and

- Arms 116c connecting the central body 116b to the end piece 116a.

The second pipe 116 is shown alone in Figures 7 to 9 and is preferably made in one piece, for example by additive manufacturing. The pipe 116 is for example made of metal.

In the example shown, the endpiece 116a comprises an upstream portion 116a1 configured to be engaged in the pipe 112 and a downstream portion 116a2 extending downstream and in the extension of the pipe.

The second conduit 116 comprises an annular fixing flange 140 which extends outwardly at the junction between the portions 116a1, 116a2 and which is configured to be applied and tightened axially against the flange 134 by means of fixing means of the V-neck type for example.

The portion 116a1 here extends inside the pipe 112, and at a radial distance from this pipe 112 with respect to its main axis A.

The portion 116a1 comprises at its free end located on the side of the ejectors 114 an annular flange 142 which has a generally flared shape towards the ejectors 114. As can be seen in Figures 7 and 8, this flange 142 comprises notches 143, here in the form of C or U, which are distributed around the A axis.

The number of notches 143 is equal to the number of ejectors 114 and are positioned around the axis A according to the position of the ejectors 114 around the axis A so that the bases of the ejectors, that is that is to say their ends 114a, are at least partly embedded or engaged in these notches 143.

Figures 5 and 6 show that the outer peripheral edge of the flange 142 is located closest to the inner surface of the pipe 112. Advantageously, this edge is mounted adjusted in the pipe 112 so as to eliminate any play between the collar 142 and pipe 112. The absence of play and the flared shape of the collar 142 allow the flow F1 to flow from the pipe 112 into the pipe 116 by limiting the risks of turbulence and pressure drops.

The central body 116b has an aerodynamic profile and comprises a leading edge 144 aligned with the axis A and a trailing edge 146 which is oriented according to the shape of the conduit 116. The leading edge 144 is preferably located upstream of the ejectors 114, as can be seen at . This is made possible by the fact that the body 116b projects upstream relative to the end piece 116a and in particular relative to its collar 142, as can be seen in Figures 5 and 7.

In the example shown where the pipe 116 is bent, the body 116b has a generally bent shape and its trailing edge 146 is aligned with the main axis of the outlet section of the pipe 116.

The central body 116b here has the general shape of a flattened ogive. P2 designates the flattening plane of the body 116b ( ).

As is visible at the in particular, the central body 116b has a thickness E1 in axial section in the cutting plane of the (which is perpendicular to the plane P2), which increases from the leading edge 144 to the level of the ends 114b or outputs of the ejectors 114 then which decreases from these outputs to the trailing edge 146. The body 116b thus has a maximum thickness E1 in a plane P1 perpendicular to axis A and passing through the ends 114b or outlets of the ejectors 114.

The central body 116b defines with the end piece 116a a peripheral vein 148 for the flow of the main and secondary flows F1, F2, which is divided by the arms 116c into two parts having passage cross sections, which may be identical.

The arms 116c are here diametrically opposed with respect to the axis A and extend in the same flattening plane P2 of the body 116b, as can be seen in Figures 4 and 9.

Arms 116c are substantially identical and each have an airfoil. They each have a leading edge and a trailing edge and a thickness E2 in the cutting plane of the (which is perpendicular to the plane P2), which increases from the leading edge of the arm to the level of the ends 114b or outlets of the ejectors 114 then which decreases from these outlets to the trailing edge of the arm.

Each of the parts of the vein 148 has in cross section a generally elongated shape on the one hand along the plane P2 and curved on the other hand around the axis A (cf. ). The general shape of these parts is retained up to the trailing edges of the body 116b and the arms 116c, the trailing edges of the arms being located at the level of the trailing edge of the body 116b, as can be seen in Figures 5 to 7. FIGS. 5 and 6 also show that the dimensions of these parts can be maintained from the outlets of the ejectors 114 to the trailing edges of the arms 116c and of the central body 116b.

Figures 10 to 14 illustrate a variant embodiment of the device 110 according to the invention.

Device 210 of Figures 10-14 has many similarities to device 110 of Figures 4-9.

The foregoing description given in relation to device 110 therefore applies to device 210, insofar as it is not contrary to and does not contradict what follows.

Line 112 associated with device 210 is similar to that described above.

The end piece 116a of the second pipe 116 comprises an upstream portion 116a1 configured to be engaged in the pipe 112 and a downstream portion 116a2 extending downstream and in the extension of the pipe 112.

The second conduit 116 comprises an annular fixing flange 140 which extends outwardly at the junction between the portions 116a1, 116a2 and which is configured to be applied and tightened axially against the flange 134 by means of fixing means of the screw-nut type, for example.

The portion 116a1 extends here inside the pipe 112, and is applied against the internal surface of the pipe 112, as is visible in the .

The portion 116a1 comprises at its free end located on the side of the ejectors 114 notches 143, here in the form of C or U, which are distributed around the axis A. The free end of the portion 116a1 is here located upstream of the ends 114a of the ejectors 114.

The number of notches 143 is equal to the number of ejectors 114 and are positioned around the axis A according to the position of the ejectors 114 around the axis A so that the bases of the ejectors, that is that is to say their ends 114a, are at least partly embedded or engaged in these notches 143.

The assembly, preferably adjusted, of the portion 116a1 in the pipe 112 allows the flow F1 to flow from the pipe 112 into the pipe 116 by limiting the risks of turbulence and pressure drops.

The central body 116b has an aerodynamic profile and comprises a leading edge 144 aligned with the axis A and a trailing edge 146 which is here truncated and located in a transverse plane P3 passing through the flange 140.

The pipe 116 comprises a transverse wall 150 connecting the trailing edge 146 of the body 116b to the end piece 116a. This wall 150 extends in the plane P3.

The leading edge 144 is preferably located upstream of the outlets of the ejectors 114, as can be seen at .

The central body 116b here has the general shape of a flattened ogive. P2 designates the flattening plane of the body 116b.

As is visible at the in particular, the central body 116b has a thickness E1 in axial section in the cutting plane of the (which is perpendicular to the plane P2), which increases from the leading edge 144 to the level of the ends 114b or outputs of the ejectors 114 then which decreases from these outputs to the trailing edge 146. The body 116b thus has a maximum thickness E1 in a plane P1 perpendicular to axis A and passing through the ends 114b or outlets of the ejectors 114.

The central body 116b defines with the end piece 116a a peripheral vein 148 for the flow of the main and secondary flows F1, F2, which is divided by the arms 116c into several parts having identical passage cross-sections.

The number of arms 116c is here equal to the number of ejectors 114. Figures 10 and 12 show that the arms 116c define between them passage sections each having a circular shape and which is located opposite an ejector outlet 114. The arms 116c are distributed around axis A and are positioned so as to be staggered with respect to the ejectors, around axis A.

Arms 116c are substantially identical and each have an airfoil. They each comprise a leading edge and a trailing edge and a thickness E2 which increases from the leading edge of the arm to the level of the ends 114b or outlets of the ejectors 114 then which decreases from these outlets to the edge of arm leak. The trailing edges of the arms 116c are located at the level of the trailing edge 146 of the body 116b and also connected to the transverse wall 150.

The transverse wall 150 comprises a series of holes 152 which respectively open into the parts of the vein 148 delimited by the arms 116c. The portion 116a2 of the end piece 116 is formed by pipes 154 which have first ends connected to the wall 150 and connected by the holes 152 to these parts of the vein 148.

In the example shown, the pipes 154 have bent shapes and are substantially identical. They each define a circular or oblong passage section identical or close to the passage section of each of the parts of the vein 148 contained in the portion 116a1.

Each of the parts of the vein 148 thus retains its overall shape from the outlets of the ejectors 114 to the ends of the pipes 154 opposite the wall 150. This makes it possible to guarantee flow of the flows F1, F2 in the pipe 116 as laminar as possible. and therefore to limit the risks of turbulence and pressure drops at the outlet of the ejectors 114.

The invention thus proposes a device 110, 210 for driving a main air flow for an aircraft turbomachine, in which the exhaust pipe 116 comprises a central body 116b and arms 116c which together form a reducer passage sections in the center and on the periphery of the vein at the outlet of the first pipe.

Claims (11)

Device (110) for driving a main airflow (F1) for an aircraft turbine engine (22), this device comprising:
- a first duct (112) for the flow of a main air flow (F1), this first duct having a main axis (A),
- a plurality of ejectors (114) of a secondary air flow (F2) located inside the first duct (112) and configured to eject a secondary air flow (F2) and force the flow of the main air flow (F1) in this first duct (112), said ejectors (114) being distributed around said main axis (A), and
- a second exhaust pipe (116) located at the outlet of the ejectors (114) and connected to the first pipe (112),
characterized in that said second conduit (116) comprises:
- a tubular connector (116a) configured to be connected to the first conduit (112), and
- a central body (116b) located inside the end piece (116a) and connected to this end piece by connecting arms (116c), said central body (116b) having an aerodynamic profile and comprising a leading edge (144), said central body (116b) defining with said endpiece (116a) a peripheral vein (148) for the flow of the mixture of the main (F1) and secondary (F2) flows, which is divided by said central body and said arms (116c) into at least two parts having identical passage cross-sections. Device (110) according to Claim 1, in which the arms (116c) have a substantially radial orientation with respect to the said main axis (A) and their number is between 2 and K, K being the number of ejectors (114). Device (110) according to claim 1 or 2, wherein said leading edge (144) is located upstream of the exits of the ejectors (114). Device (110) according to Claim 3, in which the central body (116b) has a thickness (E1) in axial section which increases from the said leading edge (144) to the level of the outlets of the ejectors (114) then which decreases from the outlets of the ejectors (114) to a trailing edge (146) of this body (116b). Device (110) according to one of the preceding claims, in which said leading edge (144) is aligned with said main axis (A). Device (110) according to one of the preceding claims, in which the endpiece (116a) comprises an external annular flange (140) for connection to the first pipe (112), this flange (140) being located axially at a distance from said edge attack (144) so that it can be engaged in said first pipe (112). Device (110) according to one of the preceding claims, in which the end piece (116a) comprises an external annular flange (142) engaged in the said first pipe (112), this flange (142) comprising an external peripheral edge comprising notches (143) configured to each receive a base from one of said ejectors (114). Device (110) according to one of the preceding claims, in which the said second conduit (116) has a bent shape. Device (110) according to one of the preceding claims, in which the said second conduit (116) is formed in one piece, preferably of metal. Turbomachine (22), in particular for an aircraft, comprising a device (110) according to one of the preceding claims. Turbomachine (22) according to claim 10, in which it comprises, from upstream to downstream, in the direction of gas flow in the turbomachine, an air inlet (24), at least one compressor (26), a combustion chamber (28), at least one turbine (30) and an exhaust (31), said air inlet (24) being equipped with a particle trap which is connected to said device (110).