Centrifugal rotating machine

Abstract

A centrifugal rotating machine includes a rotating shaft, an impeller, the impeller including a disk fixed to the rotating shaft and a cover covering a blade provided on the disk, and a casing which accommodates the impeller. An impeller flow path through which the fluid is pumped is formed by an upstream surface of the disk in the axial direction and an inner peripheral surface of the cover. In addition, an outer flow path is formed by an outer peripheral surface of the cover and an inner peripheral surface of the casing facing the outer peripheral surface of the cover. The outer flow path is connected to the impeller flow path at an outlet of the impeller flow path, and a protrusion portion protruding from the inner peripheral surface of the casing is provided in the outer flow path.

What is claimed is: 
     
         1 . A centrifugal rotating machine comprising:
 a rotating shaft which extends along an axis;   an impeller which is configured to pump a fluid flowing in from one side in an axial direction to an outside in a radial direction, the impeller including a disk fixed to the rotating shaft and a cover covering a blade provided on the disk; and   a casing which accommodates the impeller,   wherein an impeller flow path through which the fluid is pumped is formed by an upstream surface of the disk in the axial direction and an inner peripheral surface of the cover,   wherein an outer flow path is formed by an outer peripheral surface of the cover and an inner peripheral surface of the casing facing the outer peripheral surface of the cover,   wherein the outer flow path is connected to the impeller flow path at an outlet of the impeller flow path, and   wherein a protrusion portion protruding from the inner peripheral surface of the casing is provided in the outer flow path.   
     
     
         2 . The centrifugal rotating machine according to  claim 1 ,
 wherein a plurality of the protrusion portions are formed at intervals in a circumferential direction.   
     
     
         3 . The centrifugal rotating machine according to  claim 1 ,
 wherein the protrusion portion is provided at a predetermined region on the inner peripheral surface of the casing.   
     
     
         4 . The centrifugal rotating machine according to  claim 1 ,
 wherein the protrusion portion is provided at a position overlapping the outlet of the impeller flow path in a radial direction with respect to the axis.   
     
     
         5 . The centrifugal rotating machine according to  claim 1 , further comprising:
 a step which is provided on the outer peripheral surface of the cover and is an annual step centered on the axis in the outer flow path,   wherein the step is provided radially outside the protrusion portion.   
     
     
         6 . The centrifugal rotating machine according to  claim 1 ,
 wherein the protrusion portion is provided over the entire area of the casing inner peripheral surface in the outer flow path.   
     
     
         7 . The centrifugal rotating machine according to  claim 1 ,
 wherein the protrusion portion is curved from one side toward the other side in a circumferential direction with respect to the axis as the protrusion portion goes outward in the radial direction.   
     
     
         8 . The centrifugal rotating machine according to  claim 1 ,
 wherein the protrusion portion is twisted from one side toward the other side in a circumferential direction with respect to the axis with reference to the inner peripheral surface of the casing as the protrusion portion goes inward in the radial direction.   
     
     
         9 . The centrifugal rotating machine according to  claim 1 , further comprising:
 a seal portion which is provided on a radially inner end portion of the outer flow path and seals leakage of the fluid between the inner peripheral surface of the casing and the outer peripheral surface of the cover.   
     
     
         10 . The centrifugal rotating machine according to  claim 8 ,
 wherein the protrusion portion is twisted from a front side toward a rear side in a rotation direction of the impeller with reference to the inner peripheral surface of the casing as the protrusion portion goes inward in the radial direction.   
     
     
         11 . The centrifugal rotating machine according to  claim 1 ,
 wherein a circumferential dimension of the protrusion portion with respect to the axis gradually decreases as the protrusion portion is separated from the inner peripheral surface of the casing.   
     
     
         12 . A centrifugal rotating machine comprising:
 a rotating shaft which extends along an axis;   an impeller which is configured to pump a fluid flowing in from one side in an axial direction to an outside in a radial direction, the impeller including a disk fixed to the rotating shaft and a cover covering a blade provided on the disk; and   a casing which accommodates the impeller,   wherein an impeller flow path through which the fluid is pumped is formed by an upstream surface of the disk in the axial direction and an inner peripheral surface of the cover,   wherein an outer flow path is formed by an outer peripheral surface of the cover and an inner peripheral surface of the casing facing the outer peripheral surface of the cover,   wherein the outer flow path is connected to the impeller flow path at an outlet of the impeller flow path, and   wherein a step which is an annual step centered on the axis is provided on the outer peripheral surface of the cover in the outer flow path.