Centrifugal impeller and centrifugal compressor

Abstract

The impeller provides that when an angle made by a projection line 33 that is obtained by projecting a camber line 32 of the blade 22 onto a predetermined meridional cross section and the camber line 32 is defined as an inclination angle γθ and an inclination in a direction opposite to a rotating direction of the rotary shaft is defined to be positive, the blade 22 is formed in such a manner that the inclination angle γθ of a leading edge 22 A is zero or positive on the hub 20 side and gradually increasing toward the shroud 21 and the inclination angle is gradually decreasing from the leading edge toward a trailing edge in a flow direction of the fluid.

1 . A centrifugal impeller comprising: a hub; a shroud; and a plurality of blades disposed between the hub and the shroud, the centrifugal impeller blowing out fluid in a radial direction by rotation of a rotary shaft fixed to the hub, wherein
 when an angle made by a projection line that is obtained by projecting a camber line of the blade onto a predetermined meridional cross section and the camber line is defined as an inclination angle and an inclination in a direction opposite to a rotating direction of the rotary shaft is defined to be positive,   the blade is formed in such a manner that the inclination angle of a leading edge is zero or positive on a hub side and gradually increasing toward the shroud and the inclination angle is gradually decreasing from the leading edge toward a trailing edge in a flow direction, and   the inclination angle of the trailing edge in the blade is zero or positive on the hub side and gradually increasing toward the shroud.   
     
     
         2 . (canceled) 
     
     
         3 . The centrifugal impeller according to  claim 1 , wherein the inclination angle of the trailing edge in the blade is zero or positive over a region from the hub side to the shroud side. 
     
     
         4 . The centrifugal impeller according to  claim 1 , wherein the leading edge of the blade, when projected onto the meridional cross section, has a linear shape from the hub side to the shroud side or a shape protruded toward an upstream side of the flow direction between the hub side and the shroud side. 
     
     
         5 . A centrifugal compressor comprising the centrifugal impeller according to  claim 1 . 
     
     
         6 . The centrifugal impeller according to  claim 3 , wherein the leading edge of the blade, when projected onto the meridional cross section, has a linear shape from the hub side to the shroud side or a shape protruded toward an upstream side of the flow direction between the hub side and the shroud side. 
     
     
         7 . A centrifugal compressor comprising the centrifugal impeller according to  claim 3 . 
     
     
         8 . A centrifugal compressor comprising the centrifugal impeller according to  claim 4 .