Compressor surge prevention via distinct blade shapes

Abstract

A compressor includes a vaneless diffuser, a volute in fluid communication with the diffuser, and an impeller operable to compress a fluid stream and direct the fluid stream to the diffuser. The impeller includes a hub having an axis of rotation and a plurality of blades extending therefrom. The blades include a surface defined by an axial direction (Z), a radius (R) defined from the axis of rotation of the hub, and a polar angle (⊖), whereby ⊖ is substantially defined by the equation: ⊖=a*[natural logarithm of (R)]+b.

1 . A compressor comprising: 
 a diffuser;    a volute defining an open space in fluid communication with said diffuser; and    an impeller operable to compress a fluid stream and direct said fluid stream to said volute, said impeller including:    a hub having an axis of rotation; and    a plurality of blades extending from said hub, said blades having a surface defined by an axial direction (Z), a radius (R) defined from said axis of rotation of said hub, and a polar angle (⊖), whereby the polar angle (⊖) is substantially defined by the equation: ⊖=a*[natural logarithm of (R)]+b.    
     
     
         2 . The compressor of  claim 1 , wherein each of said blades includes a leading edge and a trailing edge, said leading edge formed proximate said hub and said trailing edge formed proximate said volute.  
     
     
         3 . The compressor of  claim 2 , wherein a and b are constants determined from a blade angle of said leading edge, said leading edge blade angle generally determined by output requirements of the compressor.  
     
     
         4 . The compressor of  claim 1 , wherein said diffuser is vaneless, said vaneless diffuser including a generally open space in fluid communication with said open space of said volute.  
     
     
         5 . The compressor of  claim 1 , wherein said impeller is a radial impeller, said radial impeller including an inducer formed proximate a leading edge of each blade.  
     
     
         6 . The compressor of  claim 5 , wherein said inducer includes a height component in said axial direction (Z) which is 5-7% of an outer diameter of said impeller.  
     
     
         7 . The compressor of  claim 1 , wherein said impeller is a mixed-flow impeller.  
     
     
         8 . The compressor of  claim 7 , further comprising an area reduction formed along each of said blades between a leading edge and a trailing edge.  
     
     
         9 . The compressor of  claim 8 , wherein said area reduction includes an area being between ⅔ and ¾ an area of said leading edge of each blade.  
     
     
         10 . The compressor of  claim 8 , wherein said area reduction is formed along each of said blades a distance X from said leading edge, said distance X approximately equal to ⅓ of a total blade length as measured along said radius (R).  
     
     
         11 . An impeller comprising: 
 a hub having an axis of rotation; and    a plurality of blades extending from said hub, said blades having a surface defined by an axial direction (Z), a radius (R) defined from said axis of rotation of said hub, and a polar angle (⊖), whereby the polar angle (⊖) is substantially defined by the equation: ⊖=a*[natural logarithm of (R)]+b.    
     
     
         12 . The impeller of  claim 11 , wherein each of said blades includes a leading edge and a trailing edge.  
     
     
         13 . The impeller of  claim 12 , wherein a and b are constants determined from a blade angle of said leading edge, said leading edge blade angle generally determined by output requirements of the compressor.  
     
     
         14 . The impeller of  claim 11 , wherein said impeller is a radial impeller, said radial impeller including an inducer formed proximate a leading edge of each blade.  
     
     
         15 . The compressor of  claim 14 , wherein said inducer includes a height component in said axial direction (Z) which is 5-7% of an outer diameter of said impeller.  
     
     
         16 . The compressor of  claim 11 , wherein said impeller is a mixed-flow impeller.  
     
     
         17 . The compressor of  claim 16 , further comprising an area reduction along each of said blades between a leading edge and a trailing edge.  
     
     
         18 . The compressor of  claim 17 , wherein said area reduction includes an area being between ⅔ and ¾ an area of a leading edge of each blade.  
     
     
         19 . The compressor of  claim 17 , wherein said area reduction is formed along each of said blades a distance X from said leading edge, said distance X approximately equal to ⅓ of a total blade length as measured along said radius (R).  
     
     
         20 . A compressor comprising: 
 a vaneless diffuser;    a volute in fluid communication with said vaneless diffuser; and    a radial impeller operable to compress a fluid stream and direct said fluid stream to said volute, said radial impeller including:    a hub having an axis of rotation; and    a plurality of blades extending from said hub, said blades having a surface defined by an axial direction (Z), a radius (R) defined from said axis of rotation of said hub, and a polar angle (⊖), whereby the polar angle (⊖) is substantially defined by the equation: ⊖=a*[natural logarithm of (R)]+b; and    an inducer formed proximate a leading edge of said blades, said inducer having a height as a function of said axial direction (Z), said height being 5-7% of an outer diameter of said radial impeller.    
     
     
         21 . A compressor comprising: 
 a vaneless diffuser;    a volute in fluid communication with said vaneless diffuser; and    a mixed-flow impeller operable to compress a fluid stream and direct said fluid stream to said volute, said mixed-flow impeller including:    a hub having an axis of rotation; and    a plurality of blades extending from said hub, said blades having a surface defined by an axial direction (Z), a radius (R) defined from said axis of rotation of said hub, and a polar angle (⊖), whereby the polar angle (⊖) is substantially defined by the equation: ⊖=a*[natural logarithm of (R)]+b; and    wherein each of said blades includes a leading edge and a trailing edge, said trailing edge having an area at or between ⅔ to ¾ an area of said leading edge.