turbine

Abstract

A turbine (1) for a turbomachine having a longitudinal axis (X), comprising: an alternating arrangement of annular rows of mobile vanes (64) and fixed vanes (65); and a radially internal annular cavity (68) radially formed inside the mobile and fixed vanes (64, 65); and a supply circuit (32) for supplying cooling air to the internal annular cavity (68), the downstream end of the supply circuit (32) comprising an internal annular row of orifices (81) and an external annular row of orifices (82) opening into the radially internal annular cavity (68), the turbine further comprising means (85) for controlling the flow rate of the air supplied to the orifices of the internal and external annular rows of orifices (81, 82).

Description

Technical Field

[0001] This disclosure relates to a turbine for a turbine engine. More specifically, this disclosure relates to the cooling of a turbine in an aircraft turbine engine. Background Technology

[0002] In turbines, it is customary to draw air from an upstream compressor, such as a high-pressure compressor, to cool components in stages with hotter environments. Cooling air from the high-pressure compressor is delivered, for example, to a low-pressure turbine or to the high-pressure turbine of the turbine. This air then purges warm air and ventilates some components of these turbines, such as disks or movable blades. This cooling reduces the risk of overheating of the turbine's movable parts, which can lead to degradation and, in the worst case, breakage.

[0003] For example, it is possible to fabricate a device on a high-pressure compressor that includes several air intake channels, which ensure the circulation of air drawn toward or toward the low-pressure turbine to cool the turbine. These channels can be cut out in the fixed housing of the turbine, particularly in the inter-turbine housing located between the high-pressure and low-pressure turbines, and provide a mechanical connection between the high-pressure and low-pressure turbine housings. The cooling air flowing through these channels then passes through this fixed housing and is injected via injectors arranged on the walls of this fixed housing into cavities radially arranged inside the high-pressure or low-pressure turbine. An example of this cooling device is described in document FR3084907A1.

[0004] However, while the cooling caused by the air injected into the cavity is beneficial for the thermal protection of the disk and thus improves its service life due to the reduction of the thermal gradient in the edge of each disk, the introduction of cooling air greatly reduces the absolute temperature level of the disk and its thermal expansion level, and can lead to an increase in radial clearance at the blade tip and thus reduce the performance of the turbine.

[0005] Therefore, there is a dual need to maintain or improve the acceptable operating performance of the turbine and to cool the turbine within this performance range. Summary of the Invention

[0006] Therefore, a turbine for a turbine having a longitudinal axis is provided, comprising:

[0007] The alternating arrangement of movable and fixed blades in annular rows, and

[0008] A radially inner annular cavity is formed radially within the movable and fixed blades.

[0009] A supply circuit is provided to supply cooling air to the internal annular cavity.

[0010] The downstream end of the supply circuit includes an inner annular row and an outer annular row of an orifice leading to the radially inner annular cavity, and the turbine further includes a component for controlling the flow rate of the supply air to the inner and outer annular rows of the orifice.

[0011] Depending on the turbine's operating conditions, the inner and outer annular sections of the orifice allow cooling air to pass through two distinct zones of the radially inner annular cavity: either the radially inner zone or the radially outer zone. The cooling air's direction within the radially inner annular cavity determines its thermal protection of the disk and optimizes turbine performance. Specifically, the airflow control mechanism actively controls the radial clearance at the blade tip by adjusting the temperature in the radially outer zone of the cavity. This control mechanism thus makes it possible to achieve an acceptable trade-off between the turbine's cooling and performance requirements.

[0012] The control components thus inject cooling air, which impacts the disk directly or indirectly. Air impacting the disk directly will be colder than air impacting it indirectly because the air impacting it indirectly experiences heating as it comes into partial contact with the cavity through the recirculation loop. The control components thus make it possible to adjust the temperature of the cooling air according to the turbine's predetermined operating objectives.

[0013] Furthermore, the control component may include a part for opening / closing the air supply to the orifice, the part being controlled by the control component. Therefore, there is active control of the opening / closing part.

[0014] Furthermore, the opening / closing component can be a valve. The valve can be a three-way valve.

[0015] Furthermore, the three-way valve can be of the on-off type, used to separately open the inner annular orifice and the outer annular orifice of the orifice.

[0016] Therefore, depending on the turbine's operating phase, the valve can open any of its outlet passages to contribute to turbine performance or cooling. During operation, the valve can, for example, sequentially close the first outlet passage and then the second outlet passage to achieve a balance between the turbine's cooling needs and performance requirements. Furthermore, opening the outlet passages prevents the formation of air recirculation loops within the radially inner annular cavity.

[0017] Instead of a three-way valve, the opening / closing component can be a combination of a first valve and a second valve, each of which is independently and actively controlled by the control component to regulate the airflow rate through the orifice of the inner annular row and the orifice of the outer annular row, respectively. In this case, in addition to the differentiated opening of each row of injectors provided by the solution offered by the three-way valve, it is also possible to regulate the amount of flow rate through either the inner or outer annular row to suit the desired level of cooling and / or heating.

[0018] In one embodiment, the turbine includes an upstream high-pressure turbine and a downstream low-pressure turbine, the high-pressure turbine and the low-pressure turbine being longitudinally separated by an inter-turbine housing, the inter-turbine housing including a plurality of radial arms extending into an annular main airflow of the turbine, the cooling air supply circuit extending inside the radial arms, and airflow control components arranged in the radial arms.

[0019] In another embodiment, a cooling air supply circuit extends through a fixed blade, and an airflow control component is radially formed inside the fixed blade.

[0020] This disclosure also relates to a turbine, such as a turbojet or turboprop engine, which includes a turbine as described above.

[0021] This disclosure further relates to an assembly for a turbine, comprising a turbine as described above, wherein a supply circuit is connected at its upstream end to a component for obtaining air from a compressor, such as a high-pressure compressor. Attached Figure Description

[0022] After reading the following detailed description and analyzing the accompanying drawings, other features, details, and advantages will become apparent, among which:

[0023] [ Figure 1 As previously described Figure 1 It is a schematic cross-sectional view of a turbine based on known technology;

[0024] [ Figure 2 ] Figure 2 This is a schematic cross-sectional view of an airflow control component according to a first exemplary embodiment.

[0025] [ Figure 3 ] Figure 3 This is a schematic cross-sectional view of an airflow control component according to a second exemplary embodiment. Detailed Implementation

[0026] The terms "upstream" and "downstream" are defined below with respect to the direction of gas flow through the turbine, by Figure 1 and 2The arrow F in the diagram indicates this.

[0027] Figure 1 A bypass turbine 1 is shown, which comprises, in a known manner, from upstream to downstream: at least one fan 10, an engine section comprising, in sequence, at least one stage of a low-pressure compressor 20 and a high-pressure compressor 30, a combustion chamber 40, a high-pressure turbine 50 and at least one stage of a low-pressure turbine 60.

[0028] The rotor, which rotates around the main axis X of turbine 1 and can be connected together by different transmission and gear systems, corresponds to these different components.

[0029] Furthermore, the turbine housing 70 is positioned between the high-pressure turbine 50 and the low-pressure turbine 60, and is mechanically attached to the housings of both the high-pressure turbine 50 and the low-pressure turbine 60. The turbine housing 70 specifically provides support for the bearings that rotatably guide the turbines. To reduce aerodynamic losses, the arms of this housing, which pass through the annular flow of the main air, allow the airflow to be straightened in the same manner as in the distributor stage.

[0030] A portion of the air is taken from the high-pressure compressor 30 in a known manner and delivered via one or more cooling air supply circuits 32 to cool the hotter areas of the turbine 1, particularly the high-pressure turbine 50 and the low-pressure turbine 60. Specifically, the cooling air is delivered to cavities inside the hollow turbine housing 70.

[0031] The low-pressure turbine 60 shown here includes multiple turbine stages 61. Each stage 61 includes a fixed distributor 65 and a movable disk 63 (in... Figure 1 The assembly of blades 64 (not visible in the center) is mounted to the movable disk, arranged downstream of the distributor 65, and is rotatably driven by the movable disk 63.

[0032] exist Figure 1 In the example described, the turbine housing 70 is attached to the housing 66 of the low-pressure turbine 60. The turbine housing 70 is hollow to allow cooling air to pass through it and exit via an injection device associated with the turbine housing 70, the injection device comprising a plurality of injectors 80. A movable disk 63 is rotatably integrated with a low-pressure shaft 102 extending along axis X, while each distributor 65 is connected to the housing 66.

[0033] According to this disclosure, turbine 1 includes a cooling device for delivering a portion of the air obtained from high-pressure compressor 30 to low-pressure turbine 60 via supply circuit 32. In the example described below, a portion of the obtained cooled air is distributed to an upstream stage of low-pressure turbine 60. Thus, low-pressure turbine 60 is cooled. However, the invention is not limited to this embodiment, as the extracted air portion may also be distributed to other turbine stages.

[0034] exist Figure 1 In the example described, a portion of the air obtained from the high-pressure compressor 30 flows into the supply circuit 32 and then into the hollow turbine housing 70. More precisely, the turbine housing 70 includes a plurality of radial arms extending into the annular main airflow, and the cooling air supply circuit 32 extends inside one of these radial arms. The circulation direction of the air portion through the turbine housing 70 is indicated by arrow 71. The air portion is then injected via injector 80 into the annular cavity 68, or downflow cavity 68, radially inside the annular flow of the main airflow of the turbine. The distributed air is specifically used to cool the turbine disk 63. The cooling air injected through the orifice 80 or the injector further enables the purging of warm air present in the low-pressure turbine 60, thereby cooling the low-pressure turbine. More precisely, the cooling air obtained from the high-pressure compressor 30 and delivered to the downflow cavity 68 forms a pressure barrier or purging. This pressure barrier prevents warm air from the combustion chamber and flowing in the annular main airflow of the turbine, i.e., in the main air circulation flow of the turbine 1, from entering the downflow cavity 68. This limits the risk of overheating the turbine rotor. Specifically, by preventing air from the main flow from entering the underflow cavity 68, which is at a lower temperature than the flow, the turbine rotor can therefore withstand higher centrifugal forces and is sized to reduce final stress.

[0035] Figure 2 It is similar to Figure 1 An enlarged view of the turbine section, showing the upstream portion of the low-pressure turbine 60.

[0036] Figure 2 The cooling air supply circuit 32 shown includes a radially inner upstream annular cavity 88 and a radially outer upstream annular cavity 87 upstream of the radially inner annular cavity 68. The radially inner upstream annular cavity 88 and the radially outer upstream annular cavity 87 are radially separated by a cavity partition 90. The cavity partition 90 prevents air circulation between the radially inner upstream annular cavity 88 and the radially outer upstream annular cavity 87.

[0037] The supply circuit 32 further includes an inner annular row of orifice 81 and an outer annular row of orifice 82. Orifices 81 and 82 open into a radially inner annular cavity 68. Specifically, the inner annular row of orifice 81 is arranged between an upstream radially inner annular cavity 88 and a downstream radially inner annular cavity 68. Similarly, the outer annular row of orifice 82 is arranged between an upstream radially outer upstream annular cavity 87 and a downstream radially inner annular cavity 68.

[0038] The radially inner upstream annular cavity 88 and the radially outer upstream annular cavity 87 are therefore in fluid communication with the radially inner annular cavity 68 through orifices 81 and 82.

[0039] like Figure 2 As can be seen, the turbine includes a component 85 for controlling the flow rate of supplied air to orifices 81, 82. In this example, the air flow rate control component 85 is arranged in one of the radial arms of the turbine housing 70.

[0040] Alternatively, according to another example not shown, the turbine does not include an inter-turbine housing. In this configuration, the cooling air supply circuit 32 extends through the fixed blades, and the airflow control member 85 is radially formed inside the fixed blades 65.

[0041] The control element 85 makes it possible to direct cooling air into the radially inner annular cavity 68. More precisely, depending on the turbine's intended operating performance, the control element 85 directs cooling air into either the radially inner or radially outer region of the radially inner annular cavity 68.

[0042] For this purpose, the control member 85 may include a component 86 for opening / closing the injector orifice 81, 82. The opening / closing component 86 may consist of one or more valves that regulate the airflow through the orifice. The component 86 is actively controlled by the control member 85. Through this active control, it should be understood that the component 86 is controlled by the control member 85, which sends opening / closing commands to the component 86.

[0043] like Figure 2 As shown, the control component 85 includes a valve. The valve 85 shown is arranged upstream of the radially inner upstream annular cavity 88 and the radially outer upstream annular cavity 87. The valve 85 is, for example, a three-way valve. Specifically, the three-way valve 85 allows cooling air from the high-pressure compressor 30 to be delivered to the radially inner upstream cavity 88 and the radially outer upstream cavity 87. The valve 85 has an "on / off" type, meaning that the valve 85 allows air to pass only through the orifice of the inner annular row of orifice 81 or only through the orifice of the outer annular row of orifice 82.

[0044] For example, if cooling of the disk 63 is preferred over turbine performance, valve 85 closes its passage to the radially inward upstream annular cavity 88 and opens its passage to the radially outward upstream cavity 87. Cooling air passes through the outer annular orifice of orifice 82 to the radially outer region of the radially inward annular cavity 68. Therefore, the cooling air injected into the radially inward annular cavity 68 directly impacts the disk 63 due to its proximity to it. In effect, the proximity of the outer annular orifice of orifice 82 to the disk 63 prevents the formation of air recirculation loops that contribute to air heating. Thus, the disk 63 is effectively cooled.

[0045] In a contrasting example, if turbine performance is preferred over cooling of disk 63, valve 85 closes its passage to the radially outer upstream annular cavity 87 and opens its passage to the radially inner upstream annular cavity 88. Cooling air passes through the orifices of the inner annular row of orifices 81 to reach the radially inner annular cavity 68 in a radially inner position. Therefore, the cooling air injected into the radially inner annular cavity 68 tends to heat up before reaching disk 63 due to its distance from disk 63 and the creation of an air recirculation loop.

[0046] The air from the inner annular orifice of orifice 81 is therefore warmer than the air from the outer annular orifice of orifice 82. Therefore, depending on the turbine's operating phase, valve 85 can open either of its outlet passages to aid turbine performance or cooling.

[0047] Figure 2 The example illustrates that control element 85 includes a valve. However, control element 85 is not limited to a single valve. For example, one or more baffle valves or pistons may be suitable as control element 85.

[0048] according to Figure 3 In another example shown, and alternative to a three-way valve, the opening / closing component 86 may be a combination including a first valve 861 and a second valve 862, each of which controls an orifice in one of the inner and outer annular rows. Valves 861 and 862 may be further actively controlled independently of each other. In this case, in addition to the differentiated opening of each row of orifices, the amount of flow through any row of orifices can also be regulated. In this example, the control component 85 adjusts the desired cooling and heating levels. The valves allow air to flow alternately or simultaneously, and if necessary, through the orifices of the inner annular row of orifice 81 and the orifices of the outer annular row of orifice 82 at different flow rates. Cooling air can thus pass through the orifices of the outer annular row of orifice 82 to the radially outer region of the radially inner annular cavity 68, and through the orifices of the inner annular row of orifice 81 to the radially inner region of the radially inner annular cavity 68, in order to simultaneously adjust the cooling of the disk 63 and the performance of the turbine. In other words, the cooling of the radially inner and outer regions of the radially inner annular cavity 68 is regulated by individual active control of each of the regions. Therefore, the radial clearance at the blade tip and the turbine performance are actively controlled independently of each other. In this configuration, valves 861 and 862 may, for example, be arranged upstream of the radially inner upstream cavity 88 and the radially outer upstream cavity 87, in one of the radial arms of the turbine housing 70.

Claims

1. A turbine (1) for a turbine having a longitudinal axis (X), comprising: The alternating arrangement of movable blades (64) and fixed blades (65) in annular rows A radially inner annular cavity (68) is formed radially within the movable blade and the fixed blade (64, 65). A supply circuit (32) is used to supply cooling air to the internal annular cavity (68). The downstream end of the supply circuit (32) includes an inner annular row and an outer annular row of an orifice (81) leading to the radially inner annular cavity (68), and the turbine further includes an airflow rate control member (85) for controlling the flow rate of supplied air to the inner and outer annular rows of the orifices (81, 82), wherein the airflow rate control member (85) is configured to control a component (86) for opening / closing the air supply to the orifices (81, 82), wherein: - The opening / closing component (86) is a three-way valve, or - The opening / closing component is a combination of a first valve (861) and a second valve (862), each of which is independently controlled by the airflow control component (85) to regulate the airflow through the inner annular row of the orifice (81) and the outer annular row of the orifice (82), respectively.

2. The turbine according to claim 1, characterized in that, The three-way valve (86) is of the on-off type and is used to individually open the inner annular row of the orifice (81) and the outer annular row of the orifice (82).

3. The turbine according to any one of the preceding claims, comprising an upstream high-pressure turbine (50) and a downstream low-pressure turbine (60), the high-pressure turbine (50) and the low-pressure turbine (60) being longitudinally separated by an inter-turbine housing (70), the inter-turbine housing comprising a plurality of radial arms extending into an annular flow of primary air from the turbine. The cooling air supply circuit (32) extends inside the radial arm, and the airflow control component (85) is arranged in the radial arm.

4. The turbine according to claim 1 or 2, characterized in that, The cooling air supply circuit (32) extends through the fixed blade (65), and the airflow control component (85) is radially formed inside the fixed blade (65).

5. A turbine assembly comprising a turbine (1) according to any one of the preceding claims, wherein the supply circuit (32) is connected at its upstream end to a component for obtaining air from a compressor.

6. A turbine comprising a turbine (1) according to any one of claims 1 to 4 or an assembly according to claim 5.

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