Hydrofoil with features to generate cavitation

Abstract

A hydrofoil includes a hydrofoil body that extends between a base and a tip, a leading end and a trailing end, and a suction side and a pressure side that define a thickness there between. The hydrofoil body includes a discontinuous slope on at least one of the suction side or the pressure side. The discontinuous slope extends in a span-wise direction between the base and the tip such that the discontinuous slope decreases the thickness of the hydrofoil body from the leading end to the trailing end.

1 . A hydrofoil comprising:
 a hydrofoil body extending between a base and a tip, a leading end and a trailing end, and a suction side and a pressure side that define a thickness there between, the hydrofoil body including a discontinuous slope on at least one of the suction side or the pressure side, the discontinuous slope extending in a span-wise direction between the base and the tip such that the discontinuous slope decreases the thickness of the blade body from the leading end to the trailing end.   
     
     
         2 . The rotor blade as recited in  claim 1 , wherein an apex of the discontinuous slope is closer to the trailing end than to the leading end. 
     
     
         3 . The rotor blade as recited in  claim 1 , where the discontinuous slope has an included angle of approximately 90 degrees. 
     
     
         4 . The rotor blade as recited in  claim 1 , wherein the discontinuous slope extends from the base to the tip. 
     
     
         5 . The rotor blade as recited in  claim 1 , wherein the discontinuous slope includes a face surface that lies in a plane that is transverse to the one of the suction side or the pressure side on which the discontinuous slope is. 
     
     
         6 . The rotor blade as recited in  claim 5 , wherein a normal direction of the face surface extends toward the trailing end. 
     
     
         7 . The rotor blade as recited in  claim 1 , wherein the discontinuous slope includes an apex at which a slope of the suction side changes. 
     
     
         8 . A turbopump machine comprising:
 a rotatable shaft;   a pump coupled to rotate with the rotatable shaft;   a turbine coupled to drive the rotatable shaft, the turbine including a plurality of hydrofoils that each have a hydrofoil body extending between a base and a tip, a leading end and a trailing end, and a suction side and a pressure side that define a thickness there between, the hydrofoil body including a discontinuous slope on at least one of the suction side or the pressure side, the discontinuous slope extending in a span-wise direction between the base and the tip such that the discontinuous slope decreases the thickness of the blade body from the leading end to the trailing end.   
     
     
         9 . The turbopump machine as recited in  claim 8 , wherein the pump includes an impeller. 
     
     
         10 . The turbopump machine as recited in  claim 8 , including an annular outlet extending from the turbine between an outer wall and an inner wall. 
     
     
         11 . The turbopump machine as recited in  claim 10 , wherein the annular outlet increases in size as a function of distance from the turbine. 
     
     
         12 . The turbopump machine as recited in  claim 8 , including an outlet extending from the turbine, the outlet being bounded only by an outer wall. 
     
     
         13 . The turbopump machine as recited in  claim 12 , wherein the outlet increases in size as a function of distance from the turbine. 
     
     
         14 . The turbopump machine as recited in  claim 8 , wherein the discontinuous slope has an included angle of approximately 90 degrees. 
     
     
         15 . The turbopump machine as recited in  claim 8 , wherein the discontinuous slope includes a face surface that lies in a plane that is transverse to the one of the suction side or the pressure side on which the discontinuous slope is. 
     
     
         16 . The turbopump machine as recited in  claim 8 , wherein the discontinuous slope includes an apex at which a slope changes. 
     
     
         17 . The turbopump machine as recited in  claim 8 , wherein the discontinuous slope is adapted to generate supercavitation downstream from the plurality of hydrofoils while the turbopump machine is in steady state operation. 
     
     
         18 . A method of controlling cavitation for a hydrofoil having a hydrofoil body extending between a base and a tip, a leading end and a trailing end, and a suction side and a pressure side that define a thickness there between, the method comprising:
 anchoring a starting location of a cavitation region using a discontinuous slope on at least one of the suction side or the pressure side of the hydrofoil body, the discontinuous slope extending in a span-wise direction between the base and the tip such that the discontinuous slope decreases the thickness of the hydrofoil body from the leading end to the trailing end, the cavitation region extending downstream from the hydrofoil beyond the trailing end.   
     
     
         19 . The method as recited in  claim 17 , including generating the cavitation region over less than the full span of the hydrofoil body. 
     
     
         20 . The method as recited in  claim 17 , including generating a backflow of fluid downstream from the hydrofoil body and radially inwards of the hydrofoil body to provide an inner boundary of the cavitation region. 
     
     
         21 . The method as recited in  claim 17 , including diffusing flow downstream from the hydrofoil.