MAIN AIRFLOW DRIVE DEVICE FOR AN AIRCRAFT TURBOMACHINE
By incorporating a second exhaust pipe with a strilation to channel primary and secondary flows through a limited section, the device addresses turbulence and load loss issues in main air flow training for aircraft turbomachines, improving system performance and robustness.
Patent Information
- Application Number
- FR2021005151
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2021-05-18
- Publication Date
- 2025-04-11
- Estimated Expiration
- 2041-05-18
AI Technical Summary
Existing main air flow training devices for aircraft turbomachines face challenges in managing turbulence and load losses at the output of ejectors, leading to reduced performance and potential flow reversals due to pressure loss upstream of the system.
The introduction of a second exhaust pipe with a strilation, which is a transverse narrowing that reduces the passage section, helps to better channel the jets of the ejectors, thereby reducing turbulence and load losses, and making the system more robust to upstream pressure losses.
The proposed solution effectively reduces turbulence and load losses at the output of the ejectors, enhancing the robustness of the system against upstream pressure losses and maintaining the effectiveness of the main air flow training.
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Abstract
Description
Title of the invention: DEVICE FOR DRIVING A MAIN AIR FLOW FOR AN AIRCRAFT TURBOMACHINE Technical field of the invention
[0001] The present invention relates to a device for driving a main air flow by a secondary air flow, this device being intended to equip an aircraft turbomachine. Technical background
[0002] It is known to drive a main air flow by means of a secondary air flow that is more energetic than the main air flow. A device for driving a main air flow of this type conventionally comprises a flow duct for a main air flow and ejectors for a secondary air flow located inside the duct and configured to eject the secondary air flow which will force the flow of the main air flow by viscous entrainment in this duct.
[0003] Ejectors, also called jet pumps, are supplied with high pressure and / or high temperature air. The difference in momentum between the two flows generates a viscous entrainment of the lower pressure main air flow 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.
[0004] One of the problems with this type of device concerns the control of turbulence and pressure losses 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.
[0005] When the pressure upstream of the device decreases and / or the pressure losses and turbulence are too great at the outlet of the ejectors, the suction 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 reverses and the secondary air flow is re-sucked upstream, which can damage the parts in this area.
[0006] 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 losses at the outlet of these, thus making it more robust to pressure losses upstream of the system. Summary of the invention
[0007] The invention relates to a device for driving a main air flow for an aircraft turbomachine, this device comprising:
[0008] - a first flow duct for a main air flow, this first driving with a main axis,
[0009] - 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
[0010] - a second exhaust pipe located at the outlet of the ejectors and comprising an end which is connected to one end of the first duct and which directly receives said secondary flow to force the flow of the main air flow from the first duct to the second duct,
[0011] characterized in that the end of the second pipe comprises a constriction.
[0012] The inventors have demonstrated that the center of the exhaust pipe is conducive to aerodynamic recirculation and re-aspiration of fluid leading, after a certain threshold of pressure loss upstream of the system, to a reversal of the flows.
[0013] Rather than filling the center of this pipe, the inventors propose to force the primary and secondary flows to the center of the pipe. For this, the exhaust pipe includes a constriction.
[0014] In the present application, the term "striction" means a transverse narrowing of the second pipe which results in a reduction of its passage section. A striction is therefore characterized by a constriction of the pipe and is regular over the entire periphery of the pipe. The aim is to channel the primary and secondary flows so that they pass through a restricted section, which limits the risk of turbulence and recirculation occurring in this area.
[0015] The device according to the invention may comprise one or more of the following characteristics, taken in isolation from one another, or in combination with one another:
[0016] - said constriction represents a reduction in the passage section of between 10 and 90%, preferably between 30 and 70%, and more preferably around 50%;
[0017] - said constriction comprises:
[0018] — an intermediate section comprising a passage section Smin,
[0019] — an upstream section comprising at one upstream end a passage section Smax or Smaxl substantially identical to the passage section of the first pipe, and at a downstream end a passage section Smin which is less than Smax, and
[0020] — a downstream section located between the intermediate section and the rest of the second pipe, this downstream section comprising at one upstream end a passage section Smin, and at one downstream end a passage section Smax substantially identical to the passage section of the first pipe or a passage section Smax2 between Smin and Smaxl,
[0021] and in which the upstream section has a length L1 or axial dimension less than or equal to a length L2 or axial dimension of the downstream section;
[0022] - L2 = K.L1 with K between 1 and 10, and preferably between 3 and 5;
[0023] - the end of the second pipe is engaged in the end of the first conduit or the end of the second conduit is flush with the end of the first conduit; alternatively, the first and second conduits are manufactured from a single, single piece;
[0024] - the end of the second conduit comprises a peripheral edge which extends into a plane perpendicular to said main axis, said plane passing through outlets of the ejectors or upstream of these outlets;
[0025] - said plane passes upstream of these outlets and said peripheral edge comprises notches configured to each receive a base of one of said ejectors;
[0026] - said second pipe has a generally straight or bent shape;
[0027] - said second pipe has a passage section of generally non-circular shape; alternatively, this section may be circular;
[0028] - said second pipe is formed from a single piece, preferably made of metal.
[0029] The invention further relates to a turbomachine, in particular for an aircraft, comprising a device as described above.
[0030] The invention further relates to a helicopter comprising a device or a turbomachine as described above.
[0031] Advantageously, the turbomachine comprises, from upstream to downstream, in the direction of flow of the gases in the turbomachine, an air inlet, at least one compressor, a combustion chamber, at least one turbine and an exhaust, said air inlet being equipped with a particle trap which is connected to said device. Brief description of the figures
[0032] 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:
[0033] [Fig-1] [Fig.l] is a very schematic view of a drive device of a main airflow for an aircraft turbomachine;
[0034] [Fig.2] [Fig.2] is a schematic axial sectional view of a turbomachine aircraft equipped with a device of the type shown in [Fig.l];
[0035] [Fig.3] [Fig.3] is a schematic perspective and axial sectional view of a device for driving a main air flow, according to the art prior to the present invention;
[0036] [Fig.4] [Fig.4] is a schematic perspective view of a device driving a main air flow, according to one embodiment of the invention;
[0037] [Fig.5] [Fig.5] is a larger scale view of part of the device of the [Fig.4] ; and
[0038] [Fig.6] [Fig.6] is a sectional view along line VI-VI of [Fig.4]. Detailed description of the invention
[0039] [Fig.l] 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 turbomachine.
[0040] The device 10 comprises:
[0041] - a first flow pipe 12 for the main air flow F1, this first pipe having a main axis A,
[0042] - a plurality of ejectors 14 of the secondary air flow F2, which are located inside of the first duct 12 and configured to eject the secondary air flow F2 and force the flow of the main air flow Fl into the first duct 12, and
[0043] - a second exhaust pipe 16 located at the outlet of the ejectors 14 and connected to the first pipe 12.
[0044] The device 10 is generally connected upstream (with 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 aircraft turbomachine.
[0045] The device 10 is generally connected downstream to the exterior 20 of the turbomachine.
[0046] The first pipe 12 has a generally elongated and rectilinear shape although this is not limiting. In the same way, the second pipe 16 has a generally elongated and rectilinear shape but can be bent as a variant.
[0047] 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 duct 12 which causes, by viscous friction, a flow of the main flow F1 in the duct 12. The flows F1, F2 then flow in the second duct 16 to the exterior 20 of the turbomachine.
[0048] The technology of this type of ejector or jet nozzle is well known to those skilled in the art and therefore does not need to be detailed.
[0049] [Fig.2] illustrates an example of the installation of a device 10 in a turbomachine 22, here of an aircraft of the helicopter type.
[0050] 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 a 31 exhaust.
[0051] 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 upstream. In other words, the air inlet 24 has, at the junction between these portions 24a, 24b, a maximum diameter.
[0052] The air flow FO which enters the air inlet 24 therefore flows firstly radially from the inside to the outside in the first portion 24a of the air inlet 24, then radially from the outside to the inside in the second portion 24b and up to the compressor 26. During the flow of the air flow FO in the first portion 24a, the particles potentially present in this air flow are conveyed by inertia into the enclosure 18 which is connected to the external periphery of the air inlet 24.
[0053] The device 10 extends along and on one side of the turbomachine 22. In the example shown, the first duct 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 turbine 30 and are supplied with air under pressure and / or temperature taken directly from the turbine 30 by suitable sampling means 32. The second duct 16 extends downstream of the first duct 12 and the turbine 30 and for example at an exhaust 31 for example in the form of an exhaust gas outlet nozzle.
[0054] The device 10 of [Fig.2] is therefore associated with an enclosure 18 and an air inlet 24a forming a particle trap at the inlet of the turbomachine 22.
[0055] [Fig. 3] illustrates a device 10 according to the prior art. It can be seen that the second pipe 16 is formed by a tubular wall which has a constant passage section over its entire axial extent. It can also be seen 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 losses which appear during operation at the outlet of the ejectors, as mentioned above, making it very sensitive to pressure losses upstream of the system leading to re-aspiration of the primary and secondary flows.
[0056] The present invention proposes a solution to this problem with a device 110, one embodiment of which is shown in Figures 4 to 6.
[0057] The device 110 comprises:
[0058] - a first duct 112 for the flow of the main air flow F1, this first line 112 having a main axis A,
[0059] - a plurality of ejectors 114 of the secondary air flow F2, which are located inside of the first duct 112 and configured to eject the secondary air flow F2 and force the flow of the main air flow Fl into the first duct 112, and
[0060] - a second exhaust pipe 116 located at the outlet of the ejectors 114 and connected to the first line 112.
[0061] The first pipe 112 has a generally tubular shape and can be straight or bent. It comprises a longitudinal end 112a in which the ejectors 114 are located and which comprises a free peripheral edge 112b.
[0062] The ejectors 114 are located in the first conduit 112, close to this peripheral edge 112b, and each have a generally bent shape in the example shown. Each ejector 114 is tubular and comprises an end 114a connected to an orifice (not visible) passing through the conduit 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 peripheral edge 112b ([Fig.6]).
[0063] The ends 114a of the ejectors 114 are connected via the aforementioned orifices of the pipe 112 to an annular collector 136 which is mounted around the pipe 112 and which is connected to sampling means 132 ([Fig.6]) comparable to the aforementioned sampling means 32.
[0064] The second duct 116 has an end 116a which is connected to the end 112a of the first duct 112 and which directly receives the secondary flow F2 to force the flow of the main air flow F1 from the first duct 112 to the second duct 116.
[0065] According to the invention, the end 116a of the second pipe 116 comprises a constriction 134, that is to say a reduction in its passage section. The constriction 134 makes it possible to properly channel the flow of the primary F1 and secondary F2 flows, thus eliminating the risks of turbulence and recirculation in this zone.
[0066] The reduction in passage of the constriction 134 is of the order of 10 and 90%, preferably between 30 and 70%, and more preferably of the order of 50%.
[0067] In the example shown ([Fig.6]), the constriction 134 comprises three parts or sections, namely:
[0068] - an intermediate section 134b comprising a passage section Smin,
[0069] - an upstream section 134a located between the intermediate section 134b and the ejectors 114, this upstream section 134a comprising at an upstream end 134aa a passage section Smax substantially identical to the passage section of the first pipe 112, and at a downstream end 134ab a passage section Smin which is less than Smax, and
[0070] - a downstream section 134c located between the intermediate section 134b and the rest of the second pipe 116, this downstream section 134c comprising at an upstream end 134ca a passage section Smin, and at a downstream end 134cb a passage section Smax substantially identical to the passage section of the first pipe 112.
[0071] The upstream section 134a has a length L1 or axial dimension less than a length L2 or axial dimension of the downstream section 134c. L2 = K.L1 with K included between 1 and 10, and preferably between 3 and 5.
[0072] In the example shown, the end 116a of the second pipe 116 is engaged in the end 112a of the first pipe 112. The engagement length is here greater than L1. The end 112a surrounds the sections 134a, 134b or even a part of the section 134c.
[0073] The peripheral edge 112b of the first pipe 112 is located in a plane PI which is perpendicular to the axis A and passes substantially through the downstream section 134c.
[0074] The end 116a of the second pipe 116 comprises a peripheral edge 116b which extends in a plane P2 which is perpendicular to the axis A and passes substantially through the ends 114b or outlets of the ejectors 114 or upstream of these outlets ([Fig.6]).
[0075] The second pipe 116 is preferably made in one piece, for example by additive manufacturing. The pipe 116 is for example made of metal. It has a generally straight shape in the example shown and a passage section of generally non-circular shape. This shape is flattened and for example oval or elliptical.
Claims
Claims
1. Device (110, 210) for driving a main air flow (Fl) for an aircraft turbomachine (22), this device comprising: - a first duct (112) for the flow of a main air flow (Fl), 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 (Fl) in this first duct (112), said ejectors (114) being distributed around said main axis (A) on a tubular wall of one end (112a) of the first duct (112),and - a second exhaust duct (116) located at the outlet of the ejectors (114) and comprising an end (116a) which is connected to the end (112a) of the first duct (112) and which directly receives said secondary flow (F2) to force the flow of the main air flow (F1) from the first duct (112) to the second duct (116), characterized in that the end of the second duct (116) is engaged in the end (112a) of the first duct (112) and comprises a constriction (134) which is at least partly located in this end (112a) of the first duct (112).,
2. Device (110, 210) according to claim 1, wherein said constriction (134) represents a reduction in the passage section of between 10 and 90%, preferably between 30 and 70%, and more preferably of the order of 50%.
3. Device (110, 210) according to claim 1 or 2, wherein said constriction (134) comprises: - an intermediate section (134b) having a passage section Smin, - an upstream section (134a) located between the intermediate section and the ejectors (114), this upstream section (134a) having at an upstream end (134aa) a passage section Smax or Smaxl substantially identical to the passage section of the first pipe, and at a downstream end (134ab) a passage section Smin which is less than Smax, and - a downstream section (134c) located between the intermediate section (134b) and the remainder of the second pipe, this downstream section (134c) having at a upstream end (134ca) a passage section Smin, and at a downstream end (134cb) a passage section Smax substantially identical to the passage section of the first pipe (112) or a passage section Smax2 between Smin and Smaxl, and in which the upstream section (134a) has a length L1 or axial dimension less than or equal to a length L2 or axial dimension of the downstream section (134c).
4. Device (110, 210) according to the preceding claim, in which L2 = K.L1 with K between 1 and 10, and preferably between 3 and 5.
5. Device (110, 210) according to one of the preceding claims, in which the end (116a) of the second conduit (116) comprises a peripheral edge (116b) which is flush with the tubular wall of the end (112a) of the first conduit (112).
6. Device (110, 210) according to one of the preceding claims, in which the end (116a) of the second conduit (116) comprises a peripheral edge (116b) which extends in a plane perpendicular to said main axis (A), said plane passing through outlets of the ejectors (114) or upstream of these outlets.
7. Device (210) according to the preceding claim, wherein said plane passes upstream of these outlets and said peripheral edge (116b) comprises notches (138) configured to each receive a base of one of said ejectors (114).
8. Device (110, 210) according to one of the preceding claims, in which said second conduit (116) has a generally straight or bent shape.
9. Device (110, 210) according to one of the preceding claims, wherein said second conduit (116) has a passage section of generally non-circular shape.
10. Device (110, 210) according to one of the preceding claims, wherein said second conduit (116) is formed in one piece, preferably of metal.
11. Turbomachine (22), in particular for an aircraft, comprising a device (110, 210) according to one of the preceding claims.
12. Turbomachine (22) according to claim 11, in which it comprises, from upstream to downstream, in the direction of flow of the gases 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 trap particles which is connected to said device (110, 210).