Variable stator vane and compressor

A variable stator vane includes: a stator vane body which includes a radial end surface forming a clearance between the radial end surface and an outer peripheral surface of an inner casing; a rotation shaft which is rotatable so that an angle of the stator vane body with respect to a flow direction of a main stream of a working fluid is varied and which is connected to the radial end surface; and a curved surface portion which is formed on a vane surface adjacent to the radial end surface protruding radially outward from a circumference of the rotation shaft. A curvature radius of the curved surface portion is gradually decreased with distance away from the rotation shaft.

TECHNICAL FIELD

The present invention relates to a variable stator vane and a compressor.

Priority is claimed on Japanese Patent Application No. 2017-237232, filed Dec. 11, 2017, the content of which is incorporated herein by reference.

BACKGROUND ART

Among compressors, one including a rotor body accommodated in a casing, a plurality of rotor blades radially arranged on the outside of the rotor body in the radial direction and a plurality of variable stator vanes alternately arranged with the rotor blades in the extension direction of the rotor body is known.

Patent Document 1 discloses a variable stator vane which includes a stator vane body having a pressure surface and a negative pressure surface, a first shaft portion (a first rotation shaft), and a second shaft portion (a second rotation shaft). The stator vane body is disposed between an inner casing and an outer casing.

The first shaft portion is connected to one end of the stator vane body. The first shaft portion is supported by the inner casing so as to be swingable. The second shaft portion is connected to the other end of the stator vane body. A second blade shaft is supported by the outer casing so as to be swingable.

When the variable stator vane with such a configuration is applied to a compressor, a clearance is formed between an outer peripheral surface of the inner casing and one end surface of the stator vane body and between an inner peripheral surface of the outer casing and the other end surface of the stator vane body.

CITATION LIST

SUMMARY OF INVENTION

Technical Problem

Incidentally, in the variable stator vane with such a configuration, a pressure difference generated between the negative pressure surface and the positive pressure surface at a middle area between a leading edge and a trailing edge of the stator vane body is high. For this reason, there is a problem in that a leakage flow is generated from the clearance portion so that a flow of a fluid flowing in the vicinity of the first and second shaft portions (hereinafter, referred to as the “rotation shaft”) is disturbed. Further, since the side surface of the rotation shaft directly faces the flow of main stream of the clearance portion, there is a problem that a large pressure loss is caused.

In this way, when the flow of the fluid is disturbed in the rotation shaft, the flow of the corner portion separates toward the edge of the stator vane body. As a result, there is a possibility that the pressure loss may further increase.

Here, an object of the present invention is to provide a variable stator vane and a compressor capable of preventing an occurrence of pressure loss.

Solution to Problem

In order to solve the above-described problems, a variable stator vane according to an aspect of the present invention includes: a stator vane body which is disposed in a flow path allowing a working fluid to flow therethrough and which includes a vane surface connecting two edges and a radial end surface forming a clearance between the radial end surface and a peripheral surface of a casing; a first rotation shaft which is rotatable so that an angle of the stator vane body with respect to a flow direction of a main stream of the working fluid is varied and which is connected to the radial end surface of the stator vane body; and a curved surface portion which is formed on the vane surface adjacent to the radial end surface protruding radially outward from a circumference of the first rotation shaft, wherein a curvature radius of the curved surface portion is gradually decreased with distance away from the first rotation shaft.

According to the present invention, since the variable stator vane is provided with the curved surface portion formed on the vane surface adjacent to the radial end surface protruding radially outward from the circumference of the first rotation shaft, the disturbance of the flow of the working fluid can be suppressed by the curved surface portion disposed close to the first rotation shaft in which a large pressure difference is generated on the vane surface.

Further, since the curvature radius of the curved surface portion is gradually decreased with distance away from the first rotation shaft, it is possible to allow the working fluid on the exit side of the variable stator vane to flow smoothly along the curved surface portion while preventing an increase in amount of the leakage flow occurred in the vicinity of the first rotation shaft.

Thus, since the variable stator vane is provided with the curved surface portion, an occurrence of pressure loss can be suppressed while preventing an increase in amount of a leakage flow.

Further, in the variable stator vane according to an aspect of the present invention, it may be such that the first rotation shaft includes a connection surface to which the radial end surface is connected, a fillet portion which is connected to the stator vane body to the first rotation shaft is provided between the vane surface and the connection surface, an end portion of the fillet portion is formed so as to extend outward from of the connection surface and an outer surface of the end portion of the fillet portion is as a first curved surface, at least part of a corner portion of the stator vane body which is formed so as to define the radial end surface located between the end portion of the fillet portion and the edge of the stator vane body is as a second curved surface reaching the end portion of the fillet portion and a curvature radius of the second curved surface is smaller than that of the first curved surface, and the curved surface portion includes the first curved surface and the second curved surface.

In this way, since the curved surface portion is formed of a part of the fillet portion having the first curved surface and the second curved surface formed in the corner portion of the radial end surface, wherein a curvature radius of the second curved surface is smaller than that of the first curved surface, an occurrence of pressure loss can be suppressed while preventing an increase in amount of a leakage flow.

Further, in the variable stator vane according to an aspect of the present invention, it may be such that the vane surface includes a negative pressure surface and a positive pressure surface, and the curved surface portion is formed close to the negative pressure surface.

In this way, even when the curved surface portion is disposed only on the blade surface located close to the negative pressure surface, an occurrence of pressure loss can be suppressed while preventing an increase in amount of a leakage flow.

Further, in the variable stator vane according to an aspect of the present invention, it may be such that the vane surface includes a negative pressure surface and a positive pressure surface, and the curved surface portion is formed close to the positive pressure surface.

In this way, even when the curved surface portion is disposed only in the blade surface located close to the positive pressure surface, an occurrence of pressure loss can be suppressed while preventing an increase in amount of a leakage flow.

Further, in the variable stator vane according to an aspect of the present invention, it may be such that the vane surface includes a negative pressure surface and a positive pressure surface, and the curved surface portion is formed close to each of the negative pressure surface and the positive pressure surface.

In this way, since the curved surface portion is disposed on each of the blade surface located close to the positive pressure surface and the blade surface located close to the negative pressure surface, an occurrence of pressure loss can be remarkably suppressed while preventing an increase in amount of the leakage flow.

Further, in the variable stator vane according to an aspect of the present invention, it may be such that the casing is provided with a shaft housing which is exposed from the peripheral surface of the casing and within which the first rotation shaft is accommodated, the shaft housing includes a first portion which is exposed from the peripheral surface, and a second portion which is integrally formed with the first portion and which is disposed at a position further away from the peripheral surface than the first portion, the first rotation shaft includes a recessed curved surface facing the first portion, the first portion is shaped such that a diameter of the first portion is increased from the second portion toward the peripheral surface of the casing, and the first portion includes an inclined surface which is inclined at a certain angle, a first chamfered portion which is formed between the inclined surface and an inner peripheral surface of the second portion and which is protruded in a direction toward the recessed curved surface, and a second chamfered portion which is formed between the peripheral surface and the inclined surface and which is protruded in a direction toward the recessed curved surface.

In this way, since the first portion which is exposed from the peripheral surface of the casing in the shaft housing includes the inclined surface which is inclined at a predetermined angle, the first chamfered portion which is formed between the inclined surface and the inner peripheral surface of the second portion and protrudes toward the curved portion, and the second chamfered portion which is formed between the peripheral surface of the casing and the inclined surface and protrudes toward the curved portion, a gap formed between the end of the curved portion located in the axial direction of the first rotation shaft and the first and second chamfered portions can be reduced. Accordingly, a leakage flow from being occurred between the casing and the curved portion can be suppressed.

Further, a compressor according to an aspect of the present invention includes: the above mentioned variable stator vane; a rotor including a rotor body and a plurality of rotor blades arranged in an axial direction and a circumferential direction of the rotor body; an inner casing which is provided on the outside of the rotor; an outer casing which is provided on the outside of the inner casing; and a rotational drive unit which is connected to the first rotation shaft and configured to rotate the first rotation shaft, wherein the casing is at least one of the inner casing and the outer casing.

According to the compressor with such a configuration, since the compressor is provided with the variable stator vane, an occurrence of pressure loss can be suppressed while preventing an increase in amount of a leakage flow.

Further, in the compressor according to an aspect of the present invention, it may be such that the first rotation shaft is supported by the inner casing so as to be rotatable, and the variable stator vane further comprises a second rotation shaft which is connected to the stator vane body located opposite to the first rotation shaft and which is supported by the outer casing so as to be rotatable.

Also in the compressor with such a configuration, an occurrence of pressure loss can be suppressed while preventing an increase in amount of a leakage flow.

Further, in the compressor according to an aspect of the present invention, it may be such that the curved surface portion is also disposed on the vane surface located close to the second rotation shaft.

Also in the compressor with such a configuration, an occurrence of pressure loss can be suppressed while preventing an increase in amount of a leakage flow.

Advantageous Effects of Invention

According to the present invention, an occurrence of pressure loss can be suppressed.

DESCRIPTION OF EMBODIMENTS

First Embodiment

A compressor10according to a first embodiment will be described with reference toFIG. 1toFIG. 3. InFIG. 1, an axial compressor is shown as an example of the compressor10. InFIG. 1, only a casing13and a rotor11are shown in cross-section. InFIG. 1, A indicates an area (hereinafter, referred to as an “area A”), B indicates an area (hereinafter, referred to as an “area B”), and O1indicates an axis of the rotor11(hereinafter, referred to as an “axis O1”).

Further, since it is difficult to show the clearance CL1shown inFIG. 2and the clearance CL2shown inFIG. 8inFIG. 1, these are omitted.

InFIG. 2andFIG. 3, O2indicates an axis of each of rotation shafts43and44(hereinafter, referred to as an “axis O2”). S shown inFIG. 3indicates a flow direction of a main stream of a working fluid (hereinafter, referred to as an “S direction”). InFIG. 1toFIG. 3, the same components are denoted by the same reference numerals.

The compressor10includes the rotor11, the casing13, a plurality of variable stator vane mechanisms15, and a plurality of stator vane rows17.

The rotor11includes a rotor body21, a plurality of rotor blades23, and first to sixth rotor blade rows23A to23F including the plurality of rotor blades23.

The rotor body21is a columnar member and extends in one direction. The rotor body21has a configuration in which a plurality of rotor disks (not shown) are layered. The rotor body21is rotatably supported by a bearing (not shown).

The plurality of rotor blades23are provided for each of the plurality of rotor disks. The plurality of rotor blades23respectively provided in the rotor disks are arranged in the circumferential direction and radially extend from the outer peripheral surface of the rotor disk.

Among the plurality of rotor disks, a first rotor disk which is disposed at a position closest to a suction port28of the compressor10is provided with a first rotor blade row23A. The first rotor blade row23A includes the plurality of rotor blades23which are arranged in the circumferential direction of the first rotor disk.

A second rotor blade row23B is provided in a second rotor disk disposed close to a discharge side of the first rotor disk. The third rotor blade row23C, the fourth rotor blade row23D, the fifth rotor blade row23E, and the sixth rotor blade row23F are sequentially provided close to a discharge side of the second rotor disk at predetermined intervals in a direction from the suction port28toward the discharge port.

Although only the first to sixth rotor blade rows23A to23F are shown inFIG. 1for the sake of space, the plurality of rotor blades rows are arranged in the direction of the axis O1also on the discharge side of the sixth rotor blade row23F.

The casing13includes an inner casing25and an outer casing26.

The inner casing25is a cylindrical member that is disposed on the outside of the rotor11. The inner casing25includes a shaft housing25A which accommodates the rotation shaft43of a variable stator vane35constituting the variable stator vane mechanism15. A plurality of the shaft housings25A are provided in the circumferential direction and the direction of the axis O1of the inner casing25. The inner casing25supports one end side of the variable stator vane35while the rotation shaft43is rotatable.

The outer casing26is a cylindrical member that is disposed on the outside of the inner casing25. The outer casing26includes a shaft housing26A accommodating the rotation shaft44of the variable stator vane35constituting the variable stator vane mechanism15. A plurality of the shaft housings26A are provided in the circumferential direction and the direction of the axis O1of the outer casing26.

The outer casing26supports the other end side of the variable stator vane35while the rotation shaft44is rotatable. A cylindrical flow path27is defined between the outer casing26and the inner casing25.

The casing13includes the suction port28and the discharge port (not shown). The suction port28is provided on one side of the axis O1. The suction port28communicates with the flow path27. The suction port28sucks a working fluid (for example, external air) into the casing13.

The discharge port is provided on the other side of the axis O1. The discharge port communicates with the flow path27. The discharge port discharges the working fluid compressed inside the casing13to the outside of the casing13.

The plurality of variable stator vane mechanisms15are respectively provided close to the suction port28with respect to the first to fourth rotor blade rows23A to23D.

Here, a configuration of the variable stator vane mechanism15will be described with reference toFIG. 1andFIG. 2. InFIG. 2, the same components as those of the structure shown inFIG. 1are denoted by the same reference numerals.

The variable stator vane mechanism15is provided at a plurality of positions (four as an example in the case ofFIG. 1) in the direction of the axis O1so as to be away from each other.

The variable stator vane mechanism15includes a movable ring31, a plurality of mechanical linkages33, the plurality of variable stator vanes35, and a rotational drive unit37.

The movable ring31is an annular member. The movable ring31is provided on the outside of the casing13so as to surround the casing13.

The plurality of mechanical linkages33are arranged at predetermined intervals in the circumferential direction of the movable ring31. In the plurality of mechanical linkages33, one end is fixed to the movable ring31. In the plurality of mechanical linkages33, the other end protrudes toward the suction port28.

The variable stator vane35will be described with reference toFIG. 1toFIG. 7. RegardingFIG. 4andFIG. 5, inFIG. 4, the same components as those of the structure shown inFIG. 1toFIG. 3are denoted by the same reference numerals. InFIG. 5, the same components as those of the structure shown inFIG. 4are denoted by the same reference numerals. InFIGS. 1 to 7, the same components are denoted by the same reference numerals.

The variable stator vane35includes a stator vane body41, the rotation shafts43and44, fillet portions45to48, and curved surface portions50A to50D and51A to51D. The stator vane body41is a member having an airfoil shape. The stator vane body41is disposed in the flow path27through which a working fluid flows.

The stator vane body41includes a leading edge41A and a trailing edge41B which are two edges, a positive pressure surface41aand a negative pressure surface41bwhich are vane surfaces41ab, and radial end surfaces41cand41d.

The leading edge41A is formed between the positive pressure surface41aand the negative pressure surface41b. The trailing edge41B is formed between the positive pressure surface41aand the negative pressure surface41b. The positive pressure surface41aand the negative pressure surface41bare curved surfaces.

A pressure difference generated between the positive pressure surface41aand the negative pressure surface41bis largest at a middle area between the leading edge41A and the trailing edge41B than the other area, and is gradually decreased as close to the leading edge41A or the trailing edge41B.

The radial end surface41cis disposed on one end of the stator vane body41in the direction of the axis O2(close to the inner casing25). The middle portion of the radial end surface41cis connected to the rotation shaft43.

In the stator vane body41, a leading edge side portion41AA located close to the leading edge41A and a trailing edge side portion41BB located close to the trailing edge41B are disposed so as to protrude radially outward the rotation shaft43.

Accordingly, the radial end surface41cof the leading edge side portion41AA and the radial end surface41cof the trailing edge side portion41BB face the outer peripheral surface25aof the inner casing25(the peripheral surface of the casing).

A clearance CL1is formed between each of the radial end surface41cof the leading edge side portion41AA and the radial end surface41cof the trailing edge side portion41BB and the outer peripheral surface25aof the inner casing25.

The radial end surface41dis disposed on the other end of the stator vane body41in the direction of the axis O2(close to the outer casing26). The middle portion of the radial end surface41dis connected to the rotation shaft44.

The radial end surface41dof the leading edge side portion41AA and the radial end surface41dof the trailing edge side portion41BB face the inner peripheral surface26aof the outer casing26(the peripheral surface of the casing).

A clearance CL2is formed between each of the radial end surface41dof the leading edge side portion41AA and the radial end surface41dof the trailing edge side portion41BB and the inner peripheral surface26aof the outer casing26.

The rotation shaft43includes a rotation shaft body52and an enlarged diameter portion53. The rotation shaft body52is a columnar member that extends in the direction of the axis O2. An end portion of the rotation shaft body52close to the stator vane body41is protruded from the outer peripheral surface25aof the inner casing25, and the remaining portion of the rotation shaft body52is accommodated in the shaft housing25A.

The rotation shaft43is rotated so as to change the angle of the stator vane body41with respect to the flow direction (S direction) of the main stream of the working fluid.

The enlarged diameter portion53is integrated with the rotation shaft body52. The enlarged diameter portion53is disposed between the stator vane body41and the rotation shaft body52in the direction of the axis O2. The enlarged diameter portion53has a diameter larger than the outer diameter of the rotation shaft body52.

The enlarged diameter portion53includes a connection surface53aconnected to the middle portion of the radial end surface41cof the stator vane body41.

Next, the rotation shaft44will be described with reference toFIG. 8. InFIG. 8, the same components as those of the structure shown inFIG. 1toFIG. 7are denoted by the same reference numerals.

The rotation shaft44includes a rotation shaft body55and an enlarged diameter portion56. The rotation shaft body55is a columnar member that extends in the direction of the axis O2. An end portion of the rotation shaft body55close to the stator vane body41is protruded from the inner peripheral surface26aof the outer casing26, and the remaining portion of the rotation shaft body55is accommodated in the shaft housing26A.

The enlarged diameter portion56is integrated with the rotation shaft body55. The enlarged diameter portion56is disposed between the stator vane body41and the rotation shaft body55in the direction of the axis O2. The enlarged diameter portion56has a diameter larger than the outer diameter of the rotation shaft body52.

The enlarged diameter portion56includes a connection surface56aconnected to the middle portion of the radial end surface41dof the stator vane body41.

Next, the fillet portion45will be described with reference toFIG. 3toFIG. 7. The fillet portion45is provided (in a boundary portion) between the positive pressure surface41aand the connection surface53a. The fillet portion45connects the positive pressure surface41aof the stator vane body41to the enlarged diameter portion53.

The fillet portion45is extended in a direction along the positive pressure surface41a. The fillet portion45includes an end portion45A disposed close to the leading edge41A and an end portion45B disposed close to the trailing edge41B.

Each of the end portions45A and45B is disposed on the positive pressure surface41awhich is located on the outside of the connection surface53aand in the vicinity of the radial end surface41c. Each of the end portions45A and45B includes a first curved surface45awhich is an outer surface.

The first curved surface45ais formed so that its curvature radius is gradually decreased with distance away from the enlarged diameter portion53.

The fillet portion46is provided (in a boundary portion) between the negative pressure surface41band the connection surface53aand connects the negative pressure surface41bof the stator vane body41to the enlarged diameter portion53.

The fillet portion46is extended in a direction along the negative pressure surface41b. The fillet portion46includes an end portion46A disposed close to the leading edge41A and an end portion46B disposed close to the trailing edge41B.

Each of the end portions46A and46B is disposed on the negative pressure surface41bwhich is located on the outside of the connection surface53aand in the vicinity of the radial end surface41c. Each of the end portions46A and46B includes a first curved surface46aas an outer surface.

The first curved surface46ais formed so that its curvature radius is gradually decreased with distance away from the enlarged diameter portion53.

The fillet portion47is provided (in a boundary portion) between the positive pressure surface41aand the connection surface56a. The fillet portion47connects the positive pressure surface41aof the stator vane body41to the enlarged diameter portion56.

The fillet portion47is extended in a direction along the positive pressure surface41a. The fillet portion47has the same configuration as that of the above-described fillet portion45. Specifically, the fillet portion47includes end portions45A and45B disposed on the outside of the enlarged diameter portion56, each of the end portions46A and46B has the first curved surface45a.

The fillet portion48is provided (in a boundary portion) between the negative pressure surface41band the connection surface56aand connects the negative pressure surface41bof the stator vane body41to the enlarged diameter portion56.

The fillet portion48is extended in a direction along the negative pressure surface41b. The fillet portion48has the same configuration as that of the above-described fillet portion46. Specifically, the fillet portion48includes the end portions46A and46B disposed on the outside of the enlarged diameter portion56, each of the end portions46A and46B has the first curved surface46a.

The curved surface portion50A is provided on the positive pressure surface41aadjacent to the radial end surface41cprotruding radially outward the enlarged diameter portion53. The curved surface portion50A is formed on a front area of the positive pressure surface41aextending from the enlarged diameter portion53to the leading edge41A.

The curved surface portion50A includes the first curved surface45aforming the end portion45A and a second curved surface41e.

The second curved surface41ewhich is a part of the curved surface portion50A is formed in a corner portion of the stator vane body41defining the radial end surface41clocated between the end portion45A of the fillet portion45and the leading edge41A.

The second curved surface41ewhich is the part of the curved surface portion50A reaches the end portion45A of the fillet portion45. The second curved surface41eis formed so that its curvature radius is smaller than that of the first curved surface45a, and the curvature radius of the second curved surface41eis gradually decreased with distance away from the end portion45A toward the leading edge41A.

Accordingly, the curved surface portion50A is formed so that its curvature radius is gradually decreased with distance away from the enlarged diameter portion53toward the leading edge41A.

The curved surface portion50B is provided on the positive pressure surface41aadjacent to the radial end surface41cprotruding radially outward from a circumference of the enlarged diameter portion53. The curved surface portion50B is formed on a rear area of the positive pressure surface41aextending from the enlarged diameter portion53to the trailing edge41B.

The curved surface portion50B includes the first curved surface45aforming the end portion45B and the second curved surface41e.

The second curved surface41ewhich is a part of the curved surface portion50B is formed in a corner portion of the stator vane body41that defines the radial end surface41clocated between the end portion45B of the fillet portion45and the trailing edge41B.

The second curved surface41ewhich is the part of the curved surface portion50B reaches the end portion45B of the fillet portion45. The second curved surface41eis formed so that its curvature radius is smaller than that of the first curved surface45a, and the curvature radius of the second curved surface41eis gradually decreased with distance away from the end portion45B toward the trailing edge41B.

Accordingly, the curved surface portion50B is formed so that its curvature radius is gradually decreased with distance away from the enlarged diameter portion53toward the trailing edge41B.

The curved surface portion50C is provided on the negative pressure surface41badjacent to the radial end surface41cprotruding radially outward from the circumference of the enlarged diameter portion53. The curved surface portion50C is formed on a front area of the negative pressure surface41bextending from the enlarged diameter portion53to the leading edge41A.

The curved surface portion50C includes the first curved surface46aforming the end portion46A and a second curved surface41f.

The second curved surface41fwhich is a part of the curved surface portion50C is formed in a corner portion of the stator vane body41that defines the radial end surface41clocated between the end portion46A of the fillet portion46and the leading edge41A.

The second curved surface41fwhich is the part of the curved surface portion50C reaches the end portion46A of the fillet portion46. The second curved surface41fis formed so that its curvature radius is smaller than that of the first curved surface46a, and the curvature radius of the second curved surface41eis gradually decreased with distance away from the end portion46A toward the leading edge41A.

Accordingly, the curved surface portion50C is formed so that its curvature radius is gradually decreased with distance away from the enlarged diameter portion53toward the leading edge41A.

The curved surface portion50D is provided on the negative pressure surface41badjacent to the radial end surface41cprotruding radially outward from the circumference of the enlarged diameter portion53. The curved surface portion50D is formed on a rear area of the negative pressure surface41bextending from the enlarged diameter portion53to the trailing edge41B.

The curved surface portion50D includes the first curved surface46aforming the end portion46B and the second curved surface41f.

The second curved surface41fwhich is a part of the curved surface portion50D is formed in a corner portion of the stator vane body41that defines the radial end surface41clocated between the end portion46B of the fillet portion46and the trailing edge41B.

The second curved surface41fwhich is the part of the curved surface portion50D reaches the end portion46B of the fillet portion46. The second curved surface41fis formed so that its curvature radius is smaller than that of the first curved surface46a, and the curvature radius of the second curved surface41fis gradually decreased with distance away from the end portion46B toward the trailing edge41B.

Accordingly, the curved surface portion50D is formed so that its curvature radius is gradually decreased with distance away from the enlarged diameter portion53toward the trailing edge41B.

Since the variable stator vane35is provided with the curved surface portions50A to50D, the disturbance of the flow of the working fluid in the vicinity of the radial end surface41cof the stator vane body41can be suppressed by the curved surface portions50A to50D disposed close to the enlarged diameter portion53in which a large pressure difference between the positive pressure surface41aand the negative pressure surface41bis generated.

Further, since the curvature radius of each of the curved surface portions50A to50D is gradually decreased with distance away from the enlarged diameter portion53, it is possible to allow the working fluid on the exit side of the variable stator vane35to smoothly flow along the curved surface portions50A to50D while preventing an increase in amount of the leakage flow occurred in the vicinity of the rotation shaft43.

Thus, since the variable stator vane35is provided with the curved surface portions50A to50D, an occurrence of pressure loss in the vicinity of the radial end surface41cof the stator vane body41can be suppressed while preventing an increase in amount of the leakage flow.

The curved surface portion51A is provided on the positive pressure surface41aadjacent to the radial end surface41dprotruding radially outward from a circumference of the enlarged diameter portion56. The curved surface portion51A is formed on a front area of the positive pressure surface41aextending from the enlarged diameter portion56to the leading edge41A.

The curved surface portion51A has the same formation as that of the above-described curved surface portion50A. That is, the curved surface portion51A includes the first curved surface45aforming the end portion45A and the second curved surface41e.

The curved surface portion51A is formed so that its curvature radius is gradually decreased with distance away from the enlarged diameter portion56toward the leading edge41A.

The curved surface portion51B is provided on the positive pressure surface41aadjacent to the radial end surface41dprotruding radially outward from the circumference of the enlarged diameter portion56. The curved surface portion51B is formed on a rear area of the positive pressure surface41aextending from the enlarged diameter portion56to the trailing edge41B.

The curved surface portion51B has the same formation as that of the above-described curved surface portion50B. That is, the curved surface portion51B includes the first curved surface45aforming the end portion45B and the second curved surface41e.

The curved surface portion51B is formed so that its curvature radius is gradually decreased with distance away from the enlarged diameter portion56toward the trailing edge41B.

The curved surface portion51C is provided on the negative pressure surface41badjacent to the radial end surface41dprotruding radially outward from the circumference of the enlarged diameter portion56. The curved surface portion51C is formed on a front area of the negative pressure surface41bextending from the enlarged diameter portion56to the leading edge41A.

The curved surface portion51C has the same formation as that of the above-described curved surface portion50C. That is, the curved surface portion51C includes the first curved surface46aforming the end portion46A and the second curved surface41f.

The curved surface portion51C is formed so that its curvature radius is gradually decreased with distance away from the enlarged diameter portion56toward the leading edge41A.

The curved surface portion51D is provided on the negative pressure surface41badjacent to the radial end surface41dprotruding radially outward from the circumference of the enlarged diameter portion56. The curved surface portion51D is formed on a rear area of the negative pressure surface41bextending from the enlarged diameter portion56to the trailing edge41B.

The curved surface portion51D has the same formation as that of the above-described curved surface portion50D. That is, the curved surface portion51D includes the first curved surface46aforming the end portion46B and the second curved surface41f.

The curved surface portion51D is formed so that its curvature radius is gradually decreased with distance away from the enlarged diameter portion56toward the trailing edge41B.

Since the variable stator vane35is provided with the curved surface portions51A to51D, the disturbance of the flow of the working fluid in the vicinity of the radial end surface41dof the stator vane body41can be suppressed by the curved surface portions51A to51D disposed close to the enlarged diameter portion56in which a large pressure difference between the positive pressure surface41aand the negative pressure surface41bis generated.

Further, since the curvature radius of each of the curved surface portions51A to51D is gradually decreased with distance away from the enlarged diameter portion56, it is possible to allow the working fluid on the exit side of the variable stator vane35to smoothly flow along the curved surface portions51A to51D while preventing an increase in amount of the leakage flow occurred in the vicinity of the rotation shaft44.

Thus, since the variable stator vane35is provided with the curved surface portions51A to51D, an occurrence of pressure loss in the vicinity of the radial end surface41dof the stator vane body41can be suppressed while preventing an increase in amount of the leakage flow.

Additionally, inFIG. 1, a case in which four variable stator vane mechanisms15are provided in the direction of the axis O1has been described as an example, but the number of the variable stator vane mechanisms15arranged in the direction of the axis O1may be one or more and is not limited to one.

The plurality of stator vane rows17are arranged at predetermined intervals close to the discharge side of the arrangement area of the plurality of variable stator vane mechanisms15. Each stator vane row17includes a plurality of stator vanes58fixed in the circumferential direction of the inner surface of the outer casing26. Each of the plurality of stator vanes58includes a stator vane body59. The stator vane58is disposed in the flow path27and is disposed between the rotor blades23in the direction of the axis O1.

The stator vanes58constituting the plurality of stator vane rows17are formed so that the angles of the plurality of stator vane bodies59with respect to the flow direction of the main stream of the working fluid cannot be changed.

According to the variable stator vane35of the first embodiment, since the curved surface portions50A to50D are provided close to the radial end surface41cof the stator vane body41, the disturbance of the flow of the working fluid in the vicinity of the radial end surface41cof the stator vane body41can be suppressed by the curved surface portions50A to50D disposed close to the enlarged diameter portion53in which a large pressure difference between the positive pressure surface41aand the negative pressure surface41bis generated.

Further, since the curvature radius of each of the curved surface portions50A to50D is gradually decreased with distance away from the enlarged diameter portion53, an occurrence of pressure loss in the vicinity of the radial end surface41cof the stator vane body41can be suppressed while preventing an increase in amount of the leakage flow.

Further, since the curved surface portions51A to51D are provided close to the radial end surface41dof the stator vane body41, the disturbance of the flow of the working fluid in the vicinity of the radial end surface41dof the stator vane body41can be suppressed by the curved surface portions51A to51D disposed close to the enlarged diameter portion56in which a large pressure difference between the positive pressure surface41aand the negative pressure surface41bis generated.

Further, since the curvature radius of each of the curved surface portions51A to51D is gradually decreased with distance away from the enlarged diameter portion56, an occurrence of pressure loss in the vicinity of the radial end surface41dof the stator vane body41can be suppressed while preventing an increase in amount of the leakage flow.

Additionally, in the first embodiment, a case in which four curved surface portions (the curved surface portions50A to50D) are provided close to the radial end surface41cof the stator vane body41has been described as an example. However, at least one curved surface portion of the curved surface portions50A to50D is provided close to the radial end surface41cof the stator vane body41, an occurrence of pressure loss in the vicinity of the radial end surface41ccan be suppressed while preventing an increase in amount of the leakage flow.

Further, in the first embodiment, a case in which four curved surface portions (the curved surface portions51A to51D) are provided close to the radial end surface41dof the stator vane body41has been described as an example. However, at least one curved surface portion of the curved surface portions51A to51D is provided close to the radial end surface41dof the stator vane body41, an occurrence of pressure loss in the vicinity of the radial end surface41dcan be suppressed while preventing an increase in amount of the leakage flow.

Further, in the first embodiment, a case in which the curved surface portions (the curved surface portions50A to510D and51A to51D) are provided close to both of the positive pressure surface41aand the negative pressure surface41bhas been described as an example. However, for example, only the positive pressure surface41amay be provided with the curved surface portions (specifically, the curved surface portions50A and50B or the curved surface portions50A,50B,51A, and51B) or only the negative pressure surface41bmay be provided with the curved surface portions (specifically, the curved surface portions50C and50D or the curved surface portions50C,50D,51C, and51D).

Second Embodiment

A compressor60of a second embodiment will be described with reference toFIG. 10andFIG. 11. InFIG. 10, the same components as those of the structure shown inFIG. 1toFIG. 3are denoted by the same reference numerals. InFIG. 11, the same components as those of the structure shown inFIG. 10are denoted by the same reference numerals.

Additionally, although not shown inFIG. 10andFIG. 11, the compressor60of the second embodiment includes curved surface portions50A to50D and51A to51D constituting the compressor10of the first embodiment.

The compressor60of the second embodiment has the same configuration as that of the compressor10except that the shaft housing25A and the enlarged diameter portion53constituting the compressor10of the first embodiment have a different shape.

The shaft housing25A includes a first portion61which is exposed from the outer peripheral surface25aof the inner casing25, and a second portion62which is integrally formed with the first portion61. The second portion62is disposed at a position away from the outer peripheral surface25a.

The enlarged diameter portion53includes a recessed curved surface53bfacing the first portion61.

The first portion61is shaped such that a diameter of the first portion61is increased from the second portion62toward the outer peripheral surface25a. The first portion61includes an inclined surface61a, a first chamfered portion61b, and a second chamfered portion61c.

The inclined surface61ais inclined at a certain angle. The first chamfered portion61bis formed between the inclined surface61aand the inner peripheral surface62aof the second portion62. The first chamfered portion61bprotrudes in a direction toward the curved surface53b.

The second chamfered portion61cis formed between the outer peripheral surface25aof the inner casing25and the inclined surface61a. The second chamfered portion61cis protruded in a direction toward the curved surface53b.

According to the compressor60of the second embodiment, since the curved surface53b, the inclined surface61a, the first chamfered portion61b, and the second chamfered portion61cdescribed above are provided, a gap formed between the end of the curved surface53band the first and second chamfered portions61band61ccan be reduced. Accordingly, a leakage flow from being occurred between the inner casing25and the curved surface53bcan be suppressed.

Additionally, in the second embodiment, a case in which the enlarged diameter portion53is provided with the curved surface53band the inner casing25is provided with the inclined surface61a, the first chamfered portion61b, and the second chamfered portion61chas been described as an example. However, for example, the enlarged diameter portion56may be provided with the curved surface53band the outer casing26may be provided with the inclined surface61a, the first chamfered portion61b, and the second chamfered portion61c.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments and can be modified and changed into various forms within the scope of the spirit of the present invention described in claims.

INDUSTRIAL APPLICABILITY

The present invention can be applied to the variable stator vane and the compressor.

REFERENCE SIGNS LIST