Turbine with pressurized chamber

Abstract

The invention relates to a turbine (7) comprising a first rotor (25) and a second rotor (27) able to pivot about a longitudinal axis (X) in two opposite rotation directions, the first rotor (25) comprising a radially outer drum (29) from which blades (26) extend radially inwards, the first rotor (25) and the second rotor (27) being surrounded by a stator annular portion (31), characterized in that the stator annular portion (31) delimits with the drum (29) at least one upstream annular cavity (40) and one downstream annular cavity (42) separated from each other by a sealing member (44).

Description

Technical Field

[0001] This article relates to cooling devices in the turbines of turbofan engines, such as turbo engines. Background Technology

[0002] Figure 1 This refers to a dual-flow, dual-body turbomachine. The axis of the turbomachine is marked X and corresponds to the axis of rotation of the rotating part. Hereafter, the terms axial and radial are defined relative to the axis X.

[0003] Along the airflow direction from upstream to downstream, the turbine engine 1 includes a fan 2, a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6, and a low-pressure turbine 7.

[0004] The air from fan 2 is divided into a primary flow 8 flowing in an annular primary flow path 9 and a secondary flow 10 flowing in an annular secondary flow path 11 surrounding the annular primary flow path 10.

[0005] The low-pressure compressor 3, the high-pressure compressor 4, the combustion chamber 5, the high-pressure turbine 6, and the low-pressure turbine 7 are arranged in the primary flow path 9.

[0006] The rotor of the high-pressure turbine 6 and the rotor of the high-pressure compressor 4 are rotatably coupled via the first shaft 12 to form a high-pressure spool.

[0007] The rotor of the low-pressure turbine 7 and the rotor of the low-pressure compressor 3 are rotatably coupled via a second shaft 13 to form a low-pressure spool. The fan 2 can be connected directly or via, for example, a planetary gear system to the rotor of the low-pressure compressor 3.

[0008] like Figure 2 As best shown, the low-pressure turbine 7 specifically comprises different successive stages, including a movable wheel 14 and a stationary section. The movable wheel includes a disc 15 on which blades 16 are mounted. The ends of the blades 16 are surrounded by retaining rings 17 made of a wear-resistant material, which are fastened to the turbine housing 18. A distributor 19 is located downstream of the movable wheel 14. The distributor 19 and the ring 17 are mounted on the housing via flanges or hooks 20 extending from the radially inner surface of the housing 18.

[0009] To ensure high efficiency of the turbine engine, airflow should be limited to prevent it from passing through the moving impellers 14 of different stages; that is, leakage between the radially outer ends of the blades 16 and the rings 17 made of wear-resistant material should be limited. For this purpose, the clearance at this interface should be controlled, which depends on the temperature of the housing 18, and more specifically, on the temperature of the area of ​​the housing 18 containing the hooks or flanges 20 of the support rings 17.

[0010] The primary airflow from combustion chamber 5 is hot and heats downstream components such as the stationary and moving parts of turbines 6 and 7.

[0011] In order to control the aforementioned clearances and prevent any premature degradation of the different stationary and moving parts of the turbine, it is necessary to provide an effective cooling component that can be easily integrated into the environment of the turbine engine.

[0012] Patent application FR 3 021 700 under the applicant's name discloses a device 21 for cooling the housing 18 of a low-pressure turbine 7, such as... Figure 3 As shown, the device includes manifold housings 22 fastened to a fixed housing of a turbine engine, each manifold housing 22 forming an axially extending channel.

[0013] Additionally, device 21 includes circumferentially extending ducts 23, also referred to as tracks, on either side of manifold housing 22. Each duct 23 includes an inlet leading to a passageway in manifold housing 22 and an exhaust port facing housing 18, allowing cooling air to enter manifold housing 22 before exiting through the port opposite housing 18 and then into the duct 23 to cool the duct. This is specifically referred to as impingement cooling because it causes the air to impinge on housing 18. This device is called LPTACC (for “Low-Pressure Turbine Active Clearance Control”).

[0014] Recent developments have led to the development of so-called counter-rotating turbines. This turbine comprises a first rotor and a second rotor. The first rotor comprises one or more stages formed by impellers and rotates about the axis X of the turbine engine in a first rotational direction. The second rotor comprises one or more stages formed by impellers and rotates about the axis X in a second rotational direction opposite to the first rotational direction.

[0015] The first rotor includes a radially outer drum, from which blades extend radially inward. The second rotor includes a radially inner drum, from which blades extend radially outward.

[0016] The rotor should be cooled, especially the radially outer drum of the first rotor.

[0017] It has been proven that using the LPTACC type cooling device as described above is irrelevant. In fact, using a fixed track to impact and cool the rotating drum is ineffective because during drum rotation, a boundary air layer surrounds the drum, and the airflow from the orifices of the track is sheared by the rotation of the drum and the boundary layer, thus significantly reducing cooling efficiency.

[0018] In current technology, the radially outer drum and the outer annular shell define an annular space, which is supplied with cooling air by air drawn from the high-pressure compressor. This reduces the compressor's efficiency. Furthermore, a high piston effect exists due to a pressure difference equal to the total expansion of the turbine at the downstream end of the first rotor. Summary of the Invention

[0019] This document relates to a turbine comprising a first rotor and a second rotor pivotable about a longitudinal axis in two opposing directions of rotation, the first rotor including a radially outer drum from which blades extend radially inward, the first rotor and the second rotor being surrounded by a stator annular portion, characterized in that the stator annular portion and the drum define at least one upstream annular cavity and a downstream annular cavity separated from each other by a sealing member, the upstream annular cavity being connected to a first member for supplying cooling air at a first pressure, and the downstream annular cavity being connected to a second member for supplying cooling air at a second pressure less than the first pressure.

[0020] In this way, cold air is supplied to the upstream annular cavity via high-pressure air to purge and pressurize it. This allows hot air from the flow path to be prevented from flowing out of the drum. Since a high-pressure air supply would reduce the efficiency of a turbine engine, as it is typically drawn into the compressor, the aim is to provide a minimum and therefore pressurize the annular cavity, which has a small volume.

[0021] Cooling air with low pressure is supplied to the downstream annular cavity, and this air has proven to have a much smaller impact on the efficiency of the turbine engine. This cooling air is inexpensive and can be used in large installations. However, the low supply pressure of this cooling air does not allow for the purging of the entire annular space, i.e., both the upstream and downstream annular cavities, which explains the separation of the two cavities by a sealing member. Downstream of the outer drum, air expands, and slightly pressurized air from the secondary flow path can still be incorporated into the primary flow path.

[0022] The upstream annular cavity may be an annular cavity formed at the upstream end of the turbine. This upstream annular cavity surrounds the upstream end of the radially outer drum.

[0023] Separating the two annular cavities with a sealing member allows for limiting the "piston" effect on the turbine. Positioning the sealing member downstream of the annular blade row of the first rotor achieves an optimal trade-off between limiting the piston effect and purging the upstream annular cavity with high-pressure air.

[0024] According to another feature, the first cooling air supply component has a first temperature that is lower than the second temperature of the second air supply component.

[0025] The upstream annular cavity can be in fluid communication with the annular airflow path extending inside the blade, which is defined radially outward by the drum of the first rotor and radially inward by the radially inner drum of the second rotor.

[0026] The downstream annular cavity can be in fluid communication with the annular airflow path extending inside the blade.

[0027] The upstream end of the drum can define a first annular air passage with the stator annular portion, the first annular air passage having an annular airflow path in which blades extend.

[0028] The downstream end of the first rotor's drum can define a second annular passage with the stator annular portion, the second annular passage having an annular airflow path in which blades extend.

[0029] At least one annular outer shell may be formed at the junction of at least one blade of the first rotor and the drum of the first rotor.

[0030] The first annular outer shell can be in fluid communication with the upstream annular cavity. The first outer shell can be arranged radially opposite to the upstream annular cavity.

[0031] The first annular housing may be formed at a blade located at the upstream end of the drum of the first rotor. The first housing may be in fluid communication with an annular airflow path extending radially therein from the blade.

[0032] The second annular shell can be arranged radially opposite to the downstream annular cavity. The second shell can be closed, that is, it is airtight with respect to the air in the primary flow path and the air in the downstream annular cavity.

[0033] The first and / or second air supply components may include components for controlling the opening and closing of the air supply.

[0034] The control components may include an airflow control valve, which draws the airflow into the annular secondary airflow path. In this way, active control of the turbine clearance can be achieved during operation. Controlling the cool airflow velocity in the downstream annular cavity during the cruise phase allows for a reduction in the air temperature felt by the outer drum and therefore by the outer rotor through an average temperature decrease caused by enthalpy balance, since the cool airflow velocity from the second cooling air supply component is higher than the relatively hot airflow velocity from the first supply component used to supply cooling air from the upstream annular cavity and passing through the sealing component. The first stage of the turbine does not benefit from this cooling due to the separation by the sealing component, but the temperature of the first stage of the turbine will still decrease and therefore its radial clearance will close due to conduction from downstream to upstream through the stator annular portion. Therefore, when only the second air supply component is connected to the component for controlling the airflow velocity, passive control exists at the clearance of the stage radially arranged in the upstream annular cavity, and active control exists at the clearance of the downstream stage radially arranged in the downstream annular cavity.

[0035] The drum of the first rotor can be a truncated cone with a cross-section that increases downstream.

[0036] This article also relates to a turbine engine that includes at least one turbine as described above, such as an aircraft turboprop engine or a turbojet engine.

[0037] The turbine engine allows a first cooling air supply component to be connected upstream of a first component for drawing air from a compressor, preferably a high-pressure compressor, and / or wherein a second cooling air supply component is reconnected upstream of a second component for drawing air from an annular secondary airflow path of the turbine engine, the turbine engine being a turbofan having a primary airflow and a secondary airflow coaxial with and outside the primary airflow. The annular secondary airflow path extends radially outward toward the annular portion of the stator.

[0038] It should be understood that the air from the compressor is supplied only to the upstream annular cavity and / or the air in the secondary annular airflow path is supplied only to the downstream annular cavity. Since the air in the secondary flow path is cold, air cooling is not necessary at the blade tips aligned with the downstream annular cavity.

[0039] The annular secondary airflow path in this document refers to an annular airflow path surrounding the annular primary airflow path and is well known in the prior art related to turbofans. Therefore, a turbofan engine includes a fan that blows air in both the annular primary flow path and the annular secondary flow path. According to this document, the blades of the turbine extend into the primary flow path and draw air from the secondary flow path for use in the downstream cavity.

[0040] In another embodiment, the turbine may include three consecutive annular cavities along the longitudinal axis of the turbine, namely an upstream annular cavity, an intermediate annular cavity, and a downstream annular cavity, which are separated by a sealing member.

[0041] The intermediate annular cavity can be connected to a third cooling air supply component. This air can come from a compressor, preferably from the high-pressure section of the compressor and from the area used to draw air from the compressor, which is located upstream of the air-drawing area connected to the first air supply component. This allows for the most compressed purge air and prevents air from the flow path from flowing into the cavity outside the drum of the first rotor.

[0042] At least one third annular housing may be in fluid communication with the intermediate annular cavity. The third annular housing may be arranged radially opposite to the intermediate annular cavity, and may be in fluid communication with the annular primary airflow path.

[0043] The stator annular portion can be the housing of a turbine, which can be a low-pressure turbine of a turbine engine, which can be a turbofan.

[0044] The upstream end of the turbine casing can be connected to an intermediate casing, which is inserted between the casing of the upstream high-pressure turbine and the casing of the low-pressure turbine. This intermediate casing may include substantially radially fixed blades connecting the inner annular shroud and the outer annular shroud.

[0045] The downstream end of the turbine housing can be connected to an exhaust housing, which may include an inner annular shroud and an outer annular shroud connected to each other by substantially radially fixed blades.

[0046] The casing of the low-pressure turbine can be connected to the outer annular shroud of the intermediate casing and, for example, to its downstream end, and / or to the outer annular shroud of the exhaust casing and, for example, to its upstream end. Attached Figure Description

[0047] The previously described [ Figure 1 [This is a schematic diagram of the axial cross-section of a conventional turbine engine.]

[0048] The previously described [ Figure 2 [This is a half-view of the axial section of a prior art turbine.]

[0049] The previously described [ Figure 3 [This is a perspective view of a prior art cooling device.]

[0050] [ Figure 4 ],

[0051] [ Figure 5 ],

[0052] [ Figure 6 ],as well as

[0053] [ Figure 7 Different embodiments of the turbine according to this disclosure are shown. Detailed Implementation

[0054] Figures 4 to 6 The low-pressure turbine 7 of a turbine engine according to four feasible embodiments is shown.

[0055] The turbine 7 is a counter-rotating type and includes a first rotor 25 and a second rotor 27. The first rotor includes one or more stages formed by impellers 26 and rotates about the longitudinal axis X of the turbine 7 in a first rotation direction. The second rotor includes one or more stages formed by impellers 28 and rotates about the axis X in a second rotation direction opposite to the first rotation direction.

[0056] The first rotor 25 includes a radially outer drum 29 from which blades 26 extend radially inward. The second rotor 27 includes a radially inner drum 30 from which blades 28 extend radially outward.

[0057] The first rotor 25 and the second rotor 27 are housed in a stator annular portion or a fixed housing 31, which in particular includes a radially outer annular wall 32. Blades 26 and 28 extend into an annular primary airflow path 34. The radially outer drum 29 has a truncated conical shape with a cross-section increasing downstream. The upstream end of the radially outer annular wall 32 of the outer housing 31 is connected to the downstream end of an intermediate housing 36, which is inserted between a low-pressure turbine and a high-pressure turbine (not shown). The downstream end of the radially outer annular wall 32 of the outer housing 31 is connected to the upstream end of an exhaust housing 38.

[0058] As mentioned above, it is important to ensure that the rotors 25 and 27 are cooled, specifically the radially outer drum 29 of the first rotor 25.

[0059] In various embodiments, the radially outer drum 29 and the radially outer annular wall 32 define an upstream annular cavity 40 and a downstream annular cavity 42, which are separated from each other by a sealing member 44. The upstream annular cavity 40 is formed at the upstream end of the turbine. This upstream annular cavity 40 surrounds the upstream end of the radially outer drum 29.

[0060] exist Figure 4 and 5 In the embodiment, only the upstream annular cavity 40 and the downstream annular cavity 42 exist, while Figure 5 and 6In one embodiment, the intermediate annular cavity 46 is formed longitudinally between the upstream annular cavity 40 and the downstream annular cavity 42, and the sealing member 44 separates the intermediate annular cavity 46 from the upstream annular cavity 40 and the downstream annular cavity 42.

[0061] Although not shown in the figure, it is possible to have more than three consecutive annular cavities.

[0062] The sealing member 44 includes an annular wiper 44a formed at the radially inner end of a radial annular wall 46 of the housing 31, which is connected at its radially outer end to a radially outer annular wall 32. The wiper 44a cooperates with the radially outer drum 29 to ensure a seal and prevent air circulation.

[0063] The upstream annular cavity 40 is connected to a first component 48 for supplying cooling air at a first pressure and a first temperature, and the downstream annular cavity is connected to a second component 50 for supplying cooling air at a second pressure and a second temperature lower than the first pressure and a second temperature lower than the first temperature.

[0064] In a specific example of a low-pressure turbine, a first cooling air supply member 48 is connected upstream of a first member 52 for drawing air from a compressor (not shown), such as in a high-pressure compressor, and a second cooling air supply member 50 is connected upstream of a second member 54 for drawing air from an annular secondary airflow path of a turbine fan. Therefore, the pressure and temperature of the air supplied to the upstream annular cavity 40 are higher than the pressure and temperature of the air supplied to the downstream annular cavity 42.

[0065] The second air supply component 50 may include a component 56 for controlling the opening / closing of the air supply to the downstream annular cavity 42. For example, the control component 50 may include an air flow rate control valve. The first air supply component 48 may not have any control component, and the air flow rate entering the upstream annular cavity 40 may be unregulated.

[0066] The upstream end of the radially outer drum 29 and the outer housing 31 define a first annular air passage 56, the first annular air passage having an annular primary airflow path 34 extending therein of blades 26, 28. The downstream end of the radially outer drum 29 and the outer housing 31 define a second annular air passage 58, the second annular air passage having an annular primary airflow path 34 extending therein of blades 26, 28.

[0067] An annular housing 60 may be formed at the junction of at least one blade 26 of the first rotor 29 and the radially outer drum 29. In fact, as observed in the embodiments, each blade 26 includes this housing 60.

[0068] exist Figure 4In this embodiment, a first housing 60a is formed at the blades at the upstream end of the first rotor 25. This first housing 60a communicates with the annular primary airflow path 34 and with the upstream annular cavity 40 via a downstream orifice opening. This first annular housing 60a is arranged radially at the upstream annular cavity 40. Each annular row of blades 26 arranged radially opposite to the downstream annular cavity 42 includes a second annular housing 60b, which is hermetically sealed relative to the downstream annular cavity 42 and the primary annular flow path 34, and these second housings 60b are not allowed to receive air.

[0069] The arrival of cold air in the downstream annular cavity 42 allows for a reduction in the air temperature experienced by the external annular drum 29 and thus by the external rotor, due to the average temperature decrease caused by enthalpy balance. This is because the flow rate of cold air from the second cooling air supply member 50 is higher than the flow rate of relatively hot air from the first cooling air supply member 48, from the upstream annular cavity 40, and passing through the sealing member 44. The first stage of the turbine does not benefit from this cooling due to the separation by the sealing member 44, but the temperature of the first stage of the turbine will still decrease and its radial clearance will be closed due to conduction from downstream to upstream through the stator annular portion 31.

[0070] In this embodiment, cooling air in the upstream annular cavity 40 is observed to circulate in the first annular housing 60a and then flow in the flow path 34, thereby allowing the cooling blades 26 to be arranged in an upstream annular configuration, with the blades 26 arranged adjacent to the downstream side, as shown. Figure 4 As explained in the text. Therefore, cascaded cooling exists.

[0071] exist Figure 5 In this embodiment, sealing members 44 are arranged radially outward from the first annular row of the active blades of the second rotor. The presence of a second hermetically sealed annular housing 60b is observed, but the first annular housing is absent. Air entering the upstream annular cavity 40 flows directly through the first annular passage 56 and allows pressurization of the upstream annular cavity 40. In this embodiment, reference... Figure 4 The cascade cooling mentioned does not exist. This configuration allows for minimizing the airflow velocity in the intake compressor. This solution is effective when the temperature of the primary flow path 34 is relatively low and cooling of the outer rotor 25 is not required. Air in the upstream cavity is purged to prevent air from the primary flow path from flowing radially above the outer drum, while the lower-pressure air in the downstream cavity is actually intended to cool the outer drum.

[0072] Figure 6 Corresponding to Figure 4In one embodiment, the downstream annular cavity 42 has been divided into an intermediate annular cavity 46 and a new downstream annular cavity 42. A first sealing member 44a separates the upstream annular cavity 40 and the intermediate annular cavity 46, and a second sealing member 44b separates the intermediate cavity 46 and the downstream cavity 42. These sealing members 44a and 44b may be similar to those in the previous reference. Figure 4 and 5 The sealing components described are the same.

[0073] The intermediate annular cavity 46 is connected to a third cooling air supply member 62. This air may herein be from a compressor, preferably a high-pressure compressor, and from an air suction region within the compressor, which is located upstream of the air suction region connected to the first air supply member 48. In this way, the sucked-in air is at a third pressure and a third temperature, lower than that of the first air supply member 48 but higher than that of the second air supply member 50. A first housing 60a is formed at the blade 26 at the upstream end of the first rotor 25. This first housing 60a is in fluid communication with the annular primary airflow path 34 and with the upstream annular cavity 40 via a downstream orifice opening. This first annular housing 60a is arranged radially at the upstream annular cavity 40. An annular row of blades 26 arranged radially inward from the intermediate annular cavity 46 includes a third annular housing 60c, which is in fluid communication with the intermediate annular cavity 46 and the annular primary airflow path 34. The annular row of blades 26 arranged radially inward from the downstream annular cavity 42 includes a second annular housing 60b, which is airtight and not connected to either the annular primary airflow path 34 or the downstream annular cavity 42.

[0074] Figure 7 Corresponding to Figure 5 In this embodiment, the downstream annular cavity 42 has been divided into an intermediate annular cavity 46 and a new downstream annular cavity 42. It still corresponds to... Figure 6 In one embodiment, the first sealing member 44a has moved upstream and radially outward of the annular row of blades at the upstream end of the second rotor 27. For the remainder, refer to... Figure 6 The description also applies to this figure.

[0075] exist Figure 6 and 7 In both embodiments, the third cooling air supply component 62 may include a component 64 for controlling the opening / closing of the air supply to the downstream annular cavity 42. For example, the control component 64 may include an airflow control valve.

[0076] Based on the extension of the primary airflow path, the latter two multi-chamber configurations allow for optimal satisfaction of cooling flow rate and associated pressure requirements.

Claims

1. A turbine engine comprising a turbine (7) including a first rotor (25) and a second rotor (27) pivotable about a longitudinal axis (X) in two opposing directions of rotation, the first rotor (25) including a radially outer drum (29) from which blades (26) extend radially inward, the first rotor (25) and the second rotor (27) being surrounded by a stator annular portion (31), characterized in that, The stator annular portion (31) and the drum (29) define at least one upstream annular cavity (40) and a downstream annular cavity (42) separated from each other by a sealing member (44). The upstream annular cavity (40) is connected to a first cooling air supply member (48) for supplying cooling air at a first pressure, and the downstream annular cavity is connected to a second cooling air supply member (50) for supplying cooling air at a second pressure lower than the first pressure. The first cooling air supply member (48) is connected upstream of a first member (52) for drawing air from the compressor, and / or the second cooling air supply member (50) is connected upstream of a second member (54) for drawing air from an annular secondary airflow path (34) extending radially outward toward the stator annular portion (31).

2. The turbine engine according to claim 1, characterized in that, The upstream annular cavity (40) is in fluid communication with the annular secondary airflow path (34) extending inside the blade (26), the annular secondary airflow path (34) being defined radially outward by the drum (29) of the first rotor (25) and radially inward by the radially inner drum (30) of the second rotor (27).

3. The turbine engine according to claim 2, characterized in that, The upstream end of the drum (29) of the first rotor (25) defines a first annular air passage with the stator annular portion (31), the first annular air passage having the annular secondary airflow path (34) extending inside the blade (26).

4. The turbine engine according to claim 2 or 3, characterized in that, The downstream annular cavity (42) is in fluid communication with the annular secondary airflow path (34) extending inside the blade (26).

5. The turbine engine according to claim 4, characterized in that, The downstream end of the drum (29) of the first rotor (25) defines a second annular air passage (58) with the stator annular portion (31), the second annular air passage having the annular secondary airflow path (34) extending inside the blade (26).

6. The turbine engine according to claim 1, characterized in that, At least one annular outer shell (60a, 60b, 60c) is formed at the junction of at least one blade (26) of the first rotor and the drum (29) of the first rotor (25).

7. The turbine engine according to claim 6, characterized in that, The first annular outer shell (60a) is in fluid communication with the upstream annular cavity (40).

8. The turbine engine according to claim 7, characterized in that, The first annular outer shell (60a) is formed at the blade (26) located at the upstream end of the drum (29) of the first rotor (25).

9. The turbine engine according to any one of claims 6 to 8, characterized in that, The second annular outer shell (60b) is arranged radially opposite to the downstream annular cavity (42).

10. The turbine engine according to claim 1, characterized in that, The second cooling air supply component (50) includes a component (56) for controlling the opening / closing of the air supply.

11. The turbine engine according to claim 1, characterized in that, The drum (29) of the first rotor (25) is a truncated cone with a cross section that increases downstream.

12. The turbine engine according to claim 1, characterized in that, The turbine engine is an aircraft turboprop engine or a turbojet engine.

13. The turbine engine according to claim 1, characterized in that, The first cooling air supply component (48) is connected upstream of the first component (52) used for drawing air from the high-pressure compressor.

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