Seal structure and centrifugal compressor

Abstract

Provided is a seal structure ( 50, 60 ) configured to seal a clearance ( 31, 32 ) with respect to a flow path defined by a rotary body ( 20 ) rotated about a central shaft (P) and configured to allow passage of a mainstream, and a stationary body ( 10 ) disposed at the rotary body ( 20 ) to form the clearance ( 31, 32 ), the seal structure including a seal member ( 51 A, 51 B) installed at the clearance ( 31, 32 ) and configured to divide a fluid introduced from the mainstream into the clearance ( 31, 32 ) into a high pressure side and a low pressure side, and a shifting member ( 52 A, 52 B) installed at the high pressure side of the fluid in the clearance ( 31, 32 ), and configured to allow passage of the fluid and reduce a velocity component in a rotational direction of the rotary body ( 20 ) of the velocity component of the fluid.

1 . A seal structure for sealing a clearance between a rotary body rotated around an axis and a stationary body disposed adjacent to the rotary body, in which a mainstream of a fluid passes through a passage formed by the rotary body and the stationary body, the seal structure comprising:
 a seal member installed at the clearance and configured to divide a fluid flowed into the clearance from the mainstream into a high pressure fluid and a low pressure fluid; and   a shifting member installed at an area of the high pressure fluid in the clearance, and configured to allow passage of the fluid and reduce a velocity component in a rotational direction of the rotary body in the velocity component of the fluid.   
     
     
         2 . The seal structure according to  claim 1 , wherein the shifting member applies a velocity component in a reverse direction of the rotational direction to the fluid. 
     
     
         3 . The seal structure according to  claim 1 , wherein the shifting member is installed at a fluid inlet section into which the fluid flows from the mainstream side to the clearance. 
     
     
         4 . The seal structure according to  claim 1 , wherein the shifting member is installed at the stationary body side. 
     
     
         5 . The seal structure according to  claim 4 , wherein the shifting member has a passage block section formed at the rotary body side and configured to block passage of the fluid, and
 a shifting section formed at the stationary body side, and having a through-hole passing through the mainstream side and the seal member side and formed at a position at which an aperture of the mainstream side is slightly deviated in the reverse direction of the rotational direction with respect to an aperture of the seal member side.   
     
     
         6 . The seal structure according to  claim 1 , wherein the shifting member is installed at a position of the clearance in which the rotary body and the stationary body oppose each other in the radial direction of the rotary body. 
     
     
         7 . A centrifugal compressor having a flow path defined by a rotary body and a stationary body,
 wherein the rotary body includes an impeller having a disc-shaped hub, a plurality of blades extending from the hub, and a shroud configured to cover outer circumferential ends of the plurality of blades, and   the stationary body includes a casing configured to accommodate the impeller, and an inner partition wall configured to partition the flow path into a low pressure side and a high pressure side of the mainstream,   the centrifugal compressor including:   a seal structure according to  claim 1 , the seal structure configured to seal a first clearance formed between the shroud of the impeller and the inner partition wall.   
     
     
         8 . A centrifugal compressor having a flow path defined by a rotary body and a stationary body,
 wherein the rotary body includes an impeller having a disc-shaped hub and a plurality of blades extending from the hub, and   the stationary body includes a casing configured to accommodate the impeller, and an end partition wall configured to partition the inside and the outside of the casing,   the centrifugal compressor including:   a seal structure according to  claim 1 , the seal structure configured to seal a second clearance formed between the hub of the impeller and the end partition wall.   
     
     
         9 . A centrifugal compressor having a flow path defined by a rotary body and a stationary body,
 wherein the rotary body includes an impeller having a disc-shaped hub, a plurality of blades extending from the hub, and a shroud configured to cover outer circumferential ends of the plurality of blades, and   the stationary body includes a casing configured to accommodate the impeller, an inner partition wall configured to partition the flow path into a low pressure side and a high pressure side of the mainstream, and an end partition wall configured to partition the inside and the outside of the casing,   the centrifugal compressor including:   a seal structure according to  claim 1 , the seal structure configured to seal a first clearance formed between the shroud of the impeller and the inner partition wall, and a second clearance between the hub of the impeller and the end partition wall.   
     
     
         10 . The seal structure according to  claim 2 , wherein the shifting member is installed at a fluid inlet section into which the fluid flows from the mainstream side to the clearance. 
     
     
         11 . The seal structure according to  claim 2 , wherein the shifting member is installed at the stationary body side. 
     
     
         12 . The seal structure according to  claim 3 , wherein the shifting member is installed at the stationary body side. 
     
     
         13 . The seal structure according to  claim 10 , wherein the shifting member is installed at the stationary body side. 
     
     
         14 . The seal structure according to  claim 11 , wherein the shifting member has a passage block section formed at the rotary body side and configured to block passage of the fluid, and
 a shifting section formed at the stationary body side, and having a through-hole passing through the mainstream side and the seal member side and formed at a position at which an aperture of the mainstream side is slightly deviated in the reverse direction of the rotational direction with respect to an aperture of the seal member side.   
     
     
         15 . The seal structure according to  claim 12 , wherein the shifting member has a passage block section formed at the rotary body side and configured to block passage of the fluid, and
 a shifting section formed at the stationary body side, and having a through-hole passing through the mainstream side and the seal member side and formed at a position at which an aperture of the mainstream side is slightly deviated in the reverse direction of the rotational direction with respect to an aperture of the seal member side.   
     
     
         16 . The seal structure according to  claim 13 , wherein the shifting member has a passage block section formed at the rotary body side and configured to block passage of the fluid, and
 a shifting section formed at the stationary body side, and having a through-hole passing through the mainstream side and the seal member side and formed at a position at which an aperture of the mainstream side is slightly deviated in the reverse direction of the rotational direction with respect to an aperture of the seal member side.   
     
     
         17 . The seal structure according to  claim 2 , wherein the shifting member is installed at a position of the clearance in which the rotary body and the stationary body oppose each other in the radial direction of the rotary body. 
     
     
         18 . The seal structure according to  claim 3 , wherein the shifting member is installed at a position of the clearance in which the rotary body and the stationary body oppose each other in the radial direction of the rotary body. 
     
     
         19 . The seal structure according to  claim 4 , wherein the shifting member is installed at a position of the clearance in which the rotary body and the stationary body oppose each other in the radial direction of the rotary body. 
     
     
         20 . The seal structure according to  claim 5 , wherein the shifting member is installed at a position of the clearance in which the rotary body and the stationary body oppose each other in the radial direction of the rotary body.