Diffuser for turbomachines

Abstract

A diffuser is described with an entry section close to the last stage of a turbine having an outer wall including several subsequent straight wall parts at an angle to each other followed by a curved wall part with the curved wall part connecting the straight wall parts to a diffuser lip or exit and having as vertical cross-section a non-circular 2 nd order curve, preferably part of an elliptic curve.

1 . A diffuser following the last stage of a turbine; said diffuser comprising:
 a diffuser lip;   a curved wall; and   an outer wall that extends to the diffusor lip to form a diffusor exit, the outer wall including several subsequently connected straight wall parts at an angle to each other followed by a curved wall part, wherein a curved section is located between the straight wall parts and the diffuser lip and has a vertical cross-section that forms a second order curve.   
     
     
         2 . The diffuser of  claim 1 , wherein the second order curve is not a circle segment. 
     
     
         3 . The diffuser of  claim 1 , wherein the second order curve is a segment of an elliptical curve. 
     
     
         4 . The diffuser of  claim 1 , wherein the number of straight parts is four or more. 
     
     
         5 . The diffuser of  claim 1 , wherein the second order curve is replaced by a larger number of straight parts.