JP2013144931A - Variable air bleed valve structure of multistage compressor of gas turbine engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure for driving a valve body which makes an air bleed valve body 5 close an air extraction hole more reliably when the annular air bleed valve body 5 that opens and closes the air extraction hole 10 provided in shrouds 1, 2 is displaced in a longitudinal direction above the shrouds by the swing movement of links 3, 6, in a variable air bleed valve structure of a multistage compressor of a gas turbine engine.SOLUTION: In the multistage compressor, the air bleed valve body 5 is displaced in a longitudinal direction in a spiral manner above the shrouds by the swing movement of the links 3, 6 of which one end is rotatably coupled to the air bleed valve body and the other end is rotatably coupled to the shroud 1. The links respectively includes parts 3a, 6a for elastically absorbing a load to avoid an overload state that is caused between the air bleed valve body and the shroud.

Description

  The present invention relates to a structure of a multi-stage compressor of a gas turbine engine, and more particularly to a structure of a variable bleed valve for bleed air in the multi-stage compressor.

  In a gas turbine engine used as a power source for an aircraft, air compressed by a compressor is introduced into a combustor. As such a compressor, various types of multistage axial flow compressors, multistage axial flow-centrifugal compressors, and multistage centrifugal compressors are employed. In the case of a multi-stage compressor, in the rotation range lower than the rated rotation range, the air density at the inlet of the subsequent-stage compressor is reduced by reducing the degree of compression of the air sent from the previous-stage compressor to the subsequent-stage compressor. Is reduced, the latter compressor is choked, and the air flow rate of the former compressor is restricted. Therefore, a surging state can occur in the pre-stage compressor. This surging state of the front stage compressor can be avoided by extraction (that is, leakage of a part of the air flow rate) between the front stage compressor and the rear stage compressor. Therefore, a slit or an opening (extraction hole) between the former compressor and the latter compressor is conventionally used so that extraction is performed during operation in the low rotation range (engine start, acceleration, deceleration). Is provided. In this regard, because the upstream pressure is not high in the low rotation range, a large opening area is necessary to secure the required amount of extraction, and depending on the conditions, it may be within the limits of the given space. In some cases, it may not be possible to secure a large extraction area. Therefore, a shape that can obtain a large flow coefficient is desired as the extraction hole. -On the other hand, there is no need for bleed during rated operation at high speed rotation.Continuing bleed will lead to output loss, so it is necessary to stop bleed, so leave the bleed hole open and install it at the chamber outlet outside If the bleeder is stopped by the open / close valve, the air in the chamber will flow out of the bleed hole, and the flow at the compressor inlet will be affected, leading to performance degradation. Therefore, a configuration is adopted in which the bleed hole is closed so as not to affect the compressor performance at the rated rotation that does not require bleed. (For example, Patent Documents 1-4)

Japanese Patent No. 3682976 JP2007-138816 Japanese Patent Laid-Open No. 5-125957 JP2007-231949

  Generally, in the bleed holes of a multistage compressor, a flow of bleed holes having a large flow coefficient is generated without increasing the opening area, and the compressor performance is not affected during rated operation. It is preferable that extraction can be stopped reliably. Therefore, in the Japanese Patent Application No. 2011-235213, the applicant of the present application is provided between a front-stage compressor and a rear-stage compressor in a multi-stage compressor of a gas turbine engine in order to avoid surging of the front-stage compressor. Efficient bleed can be performed in the bleed structure where the bleed differential pressure is small, and at the same time, the influence on the compressor performance is reduced in the rated rev range where bleed is not required. An example of variable bleed valve structure that can stop bleed was proposed. Specifically, in the above application, in a gas turbine engine having a multi-stage compressor, one wall of an annular bleed hole inclined in the flow direction of the compressed air at the front end of the shroud of the rear-stage compressor of the multi-stage compressor. The shroud slope is formed, and is movable in the front-rear direction along the flow direction of the compressed air at the rear end of the shroud of the front stage compressor of the multistage compressor and has the same angle as the shroud slope. An annular bleed valve body having an inclined surface that forms the other wall of the pore is provided. Then, the extraction valve body moves to a position where the inclined surface contacts the shroud inclined surface, whereby the extraction hole is closed.

  In such a configuration, since the bleed hole has a shape protruding from the plane, the bleed air flow is guided to the protruded shape, and thus the flow coefficient of the bleed hole is further increased in the open state of the bleed hole. It is improved so as to be large, and efficient extraction can be performed even in an operation region in which the pressure difference before and after the extraction hole in the low rotation region is small, and it becomes easy to secure the necessary extraction amount. Also, during rated operation, the bleed valve body is moved in the rear direction, contacts the shroud slope of the rear stage compressor, and closes the bleed hole, eliminating the flow of air in and out of the bleed hole. The effect can be suppressed.

  By the way, the movement of the bleed valve body that opens and closes the bleed hole is typically achieved by a link that moves by rotation of a drive shaft driven by an actuator provided outside. Specifically, referring to FIG. 1 or FIG. 4, the extraction valve body 5 is annular and has an inclined surface that is inclined in the flow direction of the compressed air at the same angle as the inclination angle of the shroud inclined surface 2 a. The bleed valve body 5 is connected to the link 3 extending in the front-rear direction of the shroud via the support trunk 5 a, and the link 3 is engaged with the drive shaft 4. The drive shaft 4 is connected to a rotary actuator (not shown), and when the link 3 swings due to the rotation of the drive shaft 4, the extraction valve body 5 slides back and forth while rotating spirally on the shroud 1. Displacement (see FIG. 4B). For the purpose of stabilizing the displacement of the bleed valve body 5, a plurality of support stems 8 (two in the figure) are supported on the bleed valve body 5 as shown in FIG. One end of a link 6 that is disposed at substantially equal angular intervals from the trunk 5a and is swingable with respect to each support stem 8 is connected to the link 6 in the same manner as the link 3. The other end of the link 6 is rotatably connected to a fixed shaft 7 fixed on the shroud 1. Thus, the link 6 follows the displacement of the extraction valve body 5 by the swing of the link 3, and the link 6 is also connected between the corresponding support trunk 8 and the fixed shaft 7 as schematically shown in FIG. Will be swung. In addition, the support trunks 5a and 8 of the links 3 and 6 can be absorbed so that the twist of the support trunks 5a and 8 accompanying the sliding displacement of the extraction valve body 5 as shown in FIGS. In the connecting portion, for example, a structure that allows the links 3 and 6 to tilt with respect to the axial direction of the support trunks 5a and 8 such as ball bearings 3b and 6b is provided. (Hereinafter, the link 3 connected to the drive shaft 4 is referred to as a drive link, and the link 6 connected to the fixed shaft 7 is referred to as a driven link.)

  In the configuration in which the driven link 6 is swung along with the swing of the drive link 3 by the rotation of the actuator when the bleed valve body 5 is displaced, the driven link 6 has the same length as the drive link 3. However, the links cannot simultaneously perform the same motion (the movement of the driven link 6 is delayed), and the extraction holes may not be sufficiently closed by the extraction valve body 5. As a result, an air leak may occur when the bleed hole is to be closed. Further, in actual operation of the engine, the position of the shroud slope 2a on the shroud 1 may be displaced due to the internal pressure or heat of the engine. As shown in FIG. When the link 3 and the driven link 6 are rigid bodies that hardly deform, when the drive link 3 and the driven link 6 swing by a predetermined amount, the displacement amount of the bleed valve body 5 corresponding thereto is constant. Accordingly, when the bleed hole is closed, depending on the displacement of the position of the shroud slope 2a, the inclined surface of the bleed valve body 5 cannot contact the shroud slope 2a, or the bleed hole is not sufficiently closed, or In some cases, the bleed valve body 5 strongly presses the shroud slope 2a and becomes overloaded, and the durability of the variable bleed valve structure may be impaired.

  Thus, one object of the present invention is to close the bleed hole by the bleed valve body 5 when the variable bleed valve structure is configured to achieve displacement of the bleed valve body by swinging the link. Is to improve the drive structure of the bleed valve 5 in order to ensure the above.

  According to the present invention, the above-mentioned problem is a multistage compressor for a gas turbine engine, wherein the front end of the shroud of the rear stage compressor of the multistage compressor and the rear end of the shroud of the front stage compressor of the multistage compressor. An annular bleed hole is provided between the front and rear compressor shrouds and has a valve body surface that forms one wall of the bleed hole, one end of the bleed valve. The front-rear direction is spirally moved on the shroud of the front-stage compressor or the rear-stage compressor by swinging the link that is rotatably connected to the body and whose other end is rotatably connected to the shroud of the front-stage compressor or the rear-stage compressor. The bleed valve body is provided to close the bleed hole by bringing the valve body surface into contact with the other wall of the bleed hole formed in the shroud of the former stage compressor or the latter stage compressor, and elastically applies a load to the link. There is a site to absorb It is achieved by a multi-stage compressor, characterized in that. The multistage compressor may be any of a multistage axial compressor, a multistage axial flow-centrifugal compressor in which the former stage is an axial compressor and the latter stage is a centrifugal compressor, and a multistage centrifugal compressor. In addition, the “part elastically absorbing the load” is a part that is displaced in the direction in which the load is applied and returns to the original state when released from the load, and is a part having a damper function such as a leaf spring. It may be.

  In the above configuration, the shroud is surrounded between the shroud of the front-stage compressor of the multistage compressor and the shroud of the rear-stage compressor, similarly to the extraction valve structure described in the above Japanese Patent Application No. 2011-235213. An annular extraction hole is formed by the valve body surface of the annular extraction valve body and the wall surface of the shroud. And as described above, the valve body basically moves back and forth on the shroud through a link having one end rotatably connected to the extraction valve body and the other end rotatably connected to the shroud. This is achieved by rocking with a rotary actuator or the like and rotating the extraction valve body around the central axis in a spiral shape. At this time, particularly when the bleed hole is closed, the valve body surface of the bleed valve body is swayed in order to ensure contact with the wall surface of the opposing shroud (which is displaced due to the internal pressure of the engine or heat). By increasing the movement, the amount of displacement of the extraction valve body can be increased. In this regard, as before, when the link is a rigid body, the valve body surface of the bleed valve can overload the wall surface of the shroud. Since the portion that absorbs the load is provided, even if the valve body surface of the extraction valve body and the wall surface of the shroud come into contact with each other, the valve body surface of the extraction valve body further moves in the direction of pressing the wall surface of the shroud. The load is elastically absorbed by the “part that elastically absorbs the load”, and an overload state can be suppressed.

  In short, according to the present invention described above, the “displacement of the load elastically” is provided in the link that displaces the extraction valve body by swinging, so that the displacement of the extraction valve body is provided. An increase in the amount of rocking of the link that increases the amount can be executed safely. Accordingly, the bleed valve body is designed to increase the amount of rocking of the drive link in anticipation of the displacement of the wall surface forming the surface of the bleed hole of the shroud due to the internal pressure or heat of the engine or the delay of the movement of the driven link When the displacement amount of the drive link is further increased after the valve element surface of the extraction valve body contacts the wall surface of the shroud, the swing amount absorbs the load elastically. Absorbed by the displacement of the part, thus avoiding excessively pressing the extraction valve body against the wall surface of the shroud.

  Other objects and advantages of the present invention will become apparent from the following description of preferred embodiments of the present invention.

FIG. 1 is a schematic cross-sectional view of a multi-stage compressor of a gas turbine engine having an annular variable bleed valve structure according to the present invention. FIG. 2 is a schematic perspective view of the drive link 3 and the driven link 6 used in the valve body drive mechanism according to the present invention. It is a typical perspective view. FIG. 3 is a schematic perspective view (A) and a plan view (B) of the valve body and the valve body drive mechanism in the annular variable bleed valve structure according to the present invention. FIG. 4 is a schematic perspective view (A) and a plan view (B) of the valve body and the valve body drive mechanism in the conventional annular variable extraction valve structure (Japanese Patent Application No. 2011-235213). FIG. 4C is a schematic perspective view of the drive link 3 and the driven link 6 that are used in the drive mechanism of the valve body of the previous (Japanese Patent Application No. 2011-235213).

DESCRIPTION OF SYMBOLS 1 ... Shroud of front stage compressor 1a ... Rotor of front stage compressor 1b ... Stator of front stage compressor 2 ... Shroud of rear stage compressor 2a ... Slope of front end of shroud of rear stage compressor 2b ... Impeller of rear stage compressor 3 ... Drive link 3a ... leaf spring-like part of drive link 4 ... drive shaft 5 ... annular valve body 5a ... annular valve body support trunk 6 ... driven link 6a ... leaf spring-like part of driven link 7 ... fixed shaft 8 ... annular valve body support trunk

  The present invention will now be described in detail with reference to a few preferred embodiments with reference to the accompanying drawings. In the figure, the same reference numerals indicate the same parts.

  First, referring to FIG. 1, in the gas turbine engine, the annular variable bleed valve structure according to the present embodiment is provided between the shroud 1 of the front compressor of the multistage compressor and the shroud 2 of the rear compressor. . In the illustrated multistage compressor, the front stage compressor is an axial compressor including a rotor 1a and a stator 1b, and the rear stage compressor is a centrifugal compressor including an impeller 1b and a diffuser (not shown). However, the present invention is not limited to this, and the multistage compressor to which the present invention is applied may be a multistage axial compressor or a multistage centrifugal compressor. In a multistage compressor, in a known manner, air flows from the front (left side) into the front stage compressor, and after being compressed here, the air is further compressed in the rear stage compressor. It is sent to a combustor (not shown). In such a configuration, as described above, the front-stage compressor and the rear-stage compressor are basically designed and configured so that air compression can be achieved efficiently in the rated rotation range. When the rotation is below the rated rotation range (low rotation range), sufficient compression is not achieved in the front stage compressor, resulting in a reduction in air density at the inlet of the rear stage compressor. The machine can be choked. As a result, the pre-stage compressor is in a surging state where the air flow rate is limited and the flow is stalled due to the choke state of the post-stage compressor. Therefore, conventionally, a part of the air flow rate is extracted between the shroud 1 of the front-stage compressor and the shroud 2 of the rear-stage compressor in a low rotation region, thereby preventing a surging state of the front-stage compressor. A bleed hole structure is provided. Further, when the multi-stage compressor is operated in the rated rotation region, since the extraction is not necessary, the extraction holes are configured to be closed.

  Regarding the above-described bleed hole, in particular in the present embodiment, the shape of the bleed hole is inclined in the direction of the flow of compressed air in the shroud and protrudes from the plane, and the shape of the bleed hole is maintained while maintaining this shape. The width is configured to be variable, so that the extraction can be stopped in a state where there is little influence on the compressor performance in a larger flow coefficient and a rated rotation range. Specifically, as shown in FIG. 1, the front end 2a (shroud slope) of the shroud 2 of the rear compressor protrudes outward over the entire circumference of the shroud and is further inclined in the flow direction of the compressed air. Thus, one annular wall of the bleed hole 10 is formed. Further, a bleed valve body 5 is provided facing the shroud slope 2a. As shown schematically in FIGS. 1 and 3A, the bleed valve body 5 is annular and has an inclined surface inclined in the flow direction of compressed air at the same angle as the inclination angle of the shroud inclined surface. Have.

  Further, the bleed valve body 5 is provided with a drive mechanism for displacing its position. Specifically, referring to FIGS. 1 and 4A, first, a support stem 5a is provided in the extraction valve body 5, and the support stem 5a extends substantially in the front-rear direction of the shroud. One end of the drive link 3 is rotatably connected. The other end of the drive link 3 is rotationally engaged with a drive shaft 4 that is not substantially displaced with respect to the shroud. Further, on the bleed valve body 5, a drive assist mechanism having the same structure as the support trunk 5a and the drive link 3 is further provided for the purpose of stabilizing the drive of the valve body described later. Specifically, on the bleed valve body 5, in addition to the support stem 5a, a plurality of support stems 8 are preferably provided at equiangular intervals, and each support stem 8 is substantially the same as the drive link 3. One end of a similar driven link 6 is rotatably connected. The other end of the driven link 6 is rotatably connected to a fixed shaft 7 fixed to the shroud.

  In driving the bleed valve body 5, when the drive shaft 4 is rotated by an actuator (not shown), the drive link 3 is driven as shown schematically in FIG. 4B. 4 swings around. Then, as the drive link 3 swings, the extraction valve body 5 rotates spirally on the shroud 1, and as a result, as depicted by a broken line in FIG. The position of the extraction valve body 5 in the front-rear direction of the shroud is displaced, and the opening and closing of the extraction hole 10 is achieved. The driven link 6 connected between the support stem 8 and the fixed shaft 7 is also swung with the helical displacement of the extraction valve body 5. In addition, in order to be able to absorb the torsion of the support stems 5a, 8 due to the helical displacement of the bleed valve body 5, the connecting portions of the support stems 5a, 8 of the links 3, 6 are connected to the shafts of the support stems 5a, 8 Ball bearing structures 3b and 6b that allow the links 3 and 6 to tilt with respect to the direction are provided.

  By the way, regarding the opening / closing movement of the bleed valve body 5, as described in the “Summary of the Invention” section, the movement of the driven link 6 cannot be completely synchronized with the movement of the driving link 3. There may be a delay with respect to the movement of the drive link 3. Further, the position of the shroud slope 2a may be displaced due to the internal pressure or heat of the engine during operation. In these cases, particularly when closing the bleed hole, the movement of the bleed valve body 5 may end before the inclined surface of the bleed valve body 5 completely contacts the shroud slope 2a. As a result, the bleed holes are not sufficiently closed, and the air leakage caused thereby may affect the compressor performance. Thus, in order for the inclined surface of the bleed valve body 5 to reliably contact the shroud slope 2a and to close the bleed hole reliably, the drive link is considered in consideration of the delay of movement of the driven link 6 and the displacement of the shroud slope 2a. 3 must be increased to increase the amount of displacement of the bleed valve 5. However, when the driving link 3 and the driven link 6 are substantially rigid and hardly deformed as understood from FIGS. 4B and 4C, the driving link 3 is closed when the bleed hole is closed. When the amount of swinging is excessively increased, the inclined surface of the bleed valve body 5 excessively presses the shroud inclined surface 2a, which may result in an overload state. And if the space between the inclined surface of the extraction valve body 5 and the shroud inclined surface 2a is overloaded, the durability of the extraction valve structure will be impaired.

  Therefore, in the present invention, as shown in FIG. 2, leaf spring-like portions 3a and 6a are provided in the drive link 3 and the driven link 6, and the drive link 3 and the driven link 6 are A configuration is provided that can be elastically deformed when subjected to a load.

  By providing the leaf spring-like portions 3a and 6a, the inclined surface of the extraction valve body 5 can be safely disposed without generating an overload state between the inclined surface of the extraction valve body 5 and the shroud inclined surface 2a. The amount of swing of the drive link 3 can be increased in order to ensure contact with the shroud slope 2a. Specifically, as illustrated in FIG. 3B, when the bleed hole is closed, the swing amount of the drive link 3 further increases after the inclined surface of the bleed valve body 5 contacts the shroud slope 2a. In this case, the leaf spring-like portions 3a and 6a of the drive link 3 and / or the driven link 6 are curved, and the drive link 3 and / or the driven link 6 are deformed in the direction of the arrow α in the figure. That is, the excessive swinging amount of the drive link 3 is elastically absorbed by the deformation of the drive link 3 and / or the driven link 6, and the space between the inclined surface of the extraction valve body 5 and the shroud inclined surface 2a is overloaded. It will be avoided. Thus, when the bleed hole is closed, the swing amount of the drive link 3 can be set slightly larger in consideration of the delay of the movement of the driven link 6 and the displacement of the shroud slope 2a. The contact between the inclined surface of the extraction valve body 5 and the shroud inclined surface 2a is stabilized by the elastic action caused by the deformation of the leaf spring-like portion, thereby ensuring sufficient closure of the extraction holes and air leakage or the like. The problem will be solved.

  The structure that allows elastic deformation in the drive link 3 and the driven link 6 is not limited to the leaf spring structure, and is displaced in the direction in which the load is applied, and returns to the original state when released from the load. It should be understood that any structure can be used.

  Although the above description has been made in relation to the embodiment of the present invention, many modifications and changes can be easily made by those skilled in the art, and the present invention is limited to the embodiment exemplified above. It will be apparent that the invention is not limited and applies to various devices without departing from the inventive concept.

Claims (1)

  A multistage compressor for a gas turbine engine, wherein an annular bleed hole is provided between a front end of a shroud of a rear stage compressor of the multistage compressor and a rear end of a shroud of the front stage compressor of the multistage compressor. An annular bleed valve body having a valve body surface surrounding a shroud of the front stage compressor or the rear stage compressor and forming one wall of the bleed hole, one end of which is rotatably connected to the bleed valve body And the other end is spirally displaced in the front-rear direction on the shroud of the front compressor or the rear compressor by swinging a link rotatably connected to the shroud of the front compressor or the rear compressor. A bleed valve body for closing the bleed hole by bringing the valve body surface into contact with the other wall of the bleed hole formed in the shroud of the front stage compressor or the rear stage compressor; Multistage compressor, wherein a portion to absorb the load is provided specifically.

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