Centrifugal volute pump with discontinuous vane-island diffuser

Abstract

A centrifugal pump includes a casing containing a volute channel having a cutwater at an entrance thereof. An annular vane-island diffuser is fixed in the casing concentrically within the volute. The diffuser is arranged to be separate and discontinuous from the cutwater of the volute. An impeller rotatably mounted on a shaft is disposed concentrically within the diffuser. The diffuser can be formed, e.g., by an investment casting process, integrally with the casing, or alternatively, independently of it. By arranging the diffuser to be independent of the cutwater of the volute, the diffuser can be “clocked” or “overturned” relative to the cutwater to minimize radial loads on the cutwater and dynamic loads on its leading edge. Additional advantages of the novel design include reductions in pump weight, radial loads, friction loss, design and modeling time, and the energy of outgoing acoustic waves at the pump discharge.

1 . A centrifugal pump, comprising: 
 a casing containing a volute having a cutwater at an entrance thereof;    an annular vane-island diffuser fixed in the casing concentrically within the volute, the diffuser being separate and discontinuous from the cutwater of the volute; and,    an impeller rotatably mounted on a shaft and disposed concentrically within the diffuser.    
   
   
       2 . The centrifugal pump of  claim 1 , wherein the diffuser is formed integrally with the casing.  
   
   
       3 . The centrifugal pump of  claim 1 , wherein the diffuser is formed independently of the casing.  
   
   
       4 . The centrifugal pump of  claim 1 , wherein the angular position of the diffuser relative to the cutwater of the volute is selectably adjustable.  
   
   
       5 . The centrifugal pump of  claim 4 , wherein the diffuser is overturned relative to the cutwater of the volute.  
   
   
       6 . The centrifugal pump of  claim 1 , wherein at least one of the casing and the diffuser are made by a casting process.  
   
   
       7 . The centrifugal pump of  claim 6 , wherein the casting process comprises a die-casting process or an investment-casting process.  
   
   
       8 . A centrifugal pump, comprising: 
 a casing containing a volute channel having an inlet end, an outlet end and a tapered cutwater disposed between the inlet and outlet ends and defining a first side of an inlet of the volute;    an annular vane-island diffuser comprising a plurality of identical vane-islands, each having a circumferential surface, fixed in the casing such that the circumferential surface of one of the vane islands is spaced apart from a leading edge of the cutwater and defines a second side of the inlet of the volute; and,    an impeller rotatably mounted on a shaft and disposed concentrically within the diffuser.    
   
   
       9 . The centrifugal pump of  claim 8 , wherein the diffuser is formed integrally with the casing.  
   
   
       10 . The centrifugal pump of  claim 8 , wherein the diffuser is formed independently of the casing.  
   
   
       11 . The centrifugal pump of  claim 10 , wherein the angular position of the diffuser relative to the leading edge of the cutwater is selectably adjustable.  
   
   
       12 . The centrifugal pump of  claim 8 , wherein the casing is split axially or radially.  
   
   
       13 . The centrifugal pump of  claim 9 , wherein the diffuser and the casing are formed by a casting process.  
   
   
       14 . A method of making a centrifugal pump, the method comprising: 
 providing a casing containing a volute having an inlet end, an outlet end and a tapered cutwater disposed between the inlet and outlet ends and defining a first side of an inlet of the volute;    providing an annular vane-island diffuser having a plurality of identical vane-islands; and,    fixing the diffuser concentrically in the casing such that a circumferential surface of one of the vane islands is spaced apart from a leading edge of the cutwater and defines a second side of the inlet channel of the volute.    
   
   
       15 . The method of  claim 14 , further comprising: 
 rotatably mounting an impeller concentrically within the diffuser.    
   
   
       16 . The method of  claim 14 , wherein fixing the diffuser comprises rotating the diffuser to a selected angular position relative to the leading edge of the cutwater.  
   
   
       17 . The method of  claim 14 , wherein providing the casing and the diffuser comprises forming the diffuser integrally with the casing.  
   
   
       18 . The method of  claim 14 , wherein providing the casing and the diffuser comprises casting at least one of the casing and the diffuser.  
   
   
       19 . The method of  claim 17 , wherein forming the diffuser integrally with the casing comprises casting the diffuser and the casing.  
   
   
       20 . The method of  claim 18 , wherein the casting comprises casting at least one of the casing and the diffuser using a die-casting or an investment-casting process.