Theoretical Prediction of Cavitation in Radial Inflow Turbines at Design and off-Design Conditions

Abstract

A theoretical method for the prediction of cavitation in hydraulic radial turbines isdeveloped in this work. The method combines a steady, quasi-three dimensionalanalyses which are based on the streamline curvature technique with an approach forthe prediction of cavitation based on the definition of "available" and "required"cavitation coefficients. A radial inflow turbine is selected as a test case to investigatethe capability of the present method as a cavitation prediction tool at design and offdesignconditions. The effects of various operating conditions on the cavitationinception are examined at constant values of total head and turbine suction head. It hasbeen found that cavitation is formed near the outlet when the turbine operated at thedesign speed. While at off-design speeds and flow rates, cavitation covers longerdistances along suction and pressure surfaces.