Centrifugal turbomachine

Abstract

A plurality of vaned diffusers is disposed on a concentric plate at intervals in a circumferential direction thereof, and each of the diffusers is a curvilinear element three-dimensional diffuser having blades which are extended from a hub side of a impeller to a shroud side thereof. The blades are formed in a form in which a blade serving as a reference is stacked in a direction of the height of the blade, which is a direction of a gap between the hub and the shroud. A dihedral distribution in which moving in a direction perpendicular to a chord direction linking a leading edge of the blade as the reference with a tailing edge thereof, is set as a positive movement is non-uniform from an end portion on the hub side to an intermediate portion of the height of the blade.

1 . A centrifugal turbomachine comprising: at least one or more impellers attached to an identical rotating shaft and composed of a hub, a shroud, and a plurality of circumferentially spaced apart blades between the hub and the shroud; and a vaned diffuser disposed downstream of at least one of the impellers,
 wherein: the vaned diffuser includes a plurality of circumferentially spaced apart blades in a flow passage that is formed downstream of the impeller, each of the blades being formed with basic blade profiles stacked in a blade height direction that corresponds to an axial direction of the rotating shaft; and   dihedral distribution in which movement in a direction perpendicular to a chord direction connecting leading and trailing edges of each of the basic blade profiles and in an opposite direction of rotation of the impeller is set as positive is made uneven from a hub-side end to an intermediate portion in the blade height direction on a hub wall surface side.   
     
     
         2 . The centrifugal turbomachine according to  claim 1 , wherein the dihedral distribution of each of the diffuser blades is increased from the hub-side end to the intermediate portion in the blade height direction. 
     
     
         3 . The centrifugal turbomachine according to  claim 2 , wherein, in each of the diffuser blades, an angle between a plane virtually formed at a leading edge portion on the hub-side end and a suction surface of the diffuser blade is an obtuse angle. 
     
     
         4 . The centrifugal turbomachine according to  claim 3 , wherein the dihedral distribution increases from a shroud-side end to the intermediate portion in the blade height direction and from the hub-side end to the intermediate portion in the blade height direction. 
     
     
         5 . The centrifugal turbomachine according to  claim 4 , wherein, in each of the diffuser blades, angles between a plane virtually formed at the leading edge portion on the shroud-side end and the suction surface of the diffuser blade and between a hub plate and the suction surface of the diffuser blade are each an obtuse angle. 
     
     
         6 . The centrifugal turbomachine according to  claim 1 , wherein the dihedral distribution of each of the diffuser blades decreases from the hub-side end to the intermediate portion in the blade height direction, and sweep distribution in which movement in a direction parallel to the chord direction of the basic blade profiles and in a downstream direction is set as positive is decreased from the hub-side end to the intermediate portion in the blade height direction. 
     
     
         7 . The centrifugal turbomachine according to  claim 1 , wherein at least one of the dihedral distribution and the sweep distribution is applied to at least a first half portion in a flow direction of the diffuser blades. 
     
     
         8 . The centrifugal turbomachine according to  claim 2 , wherein at least one of the dihedral distribution and the sweep distribution is applied to at least a first half portion in a flow direction of the diffuser blades. 
     
     
         9 . The centrifugal turbomachine according to  claim 3 , wherein at least one of the dihedral distribution and the sweep distribution is applied to at least a first half portion in a flow direction of the diffuser blades. 
     
     
         10 . The centrifugal turbomachine according to  claim 4 , wherein at least one of the dihedral distribution and the sweep distribution is applied to at least a first half portion in a flow direction of the diffuser blades. 
     
     
         11 . The centrifugal turbomachine according to  claim 5 , wherein at least one of the dihedral distribution and the sweep distribution is applied to at least a first half portion in a flow direction of the diffuser blades. 
     
     
         12 . The centrifugal turbomachine according to  claim 6 , wherein at least one of the dihedral distribution and the sweep distribution is applied to at least a first half portion in a flow direction of the diffuser blades.