Design and validation of transonic nozzle guide vane profile of radial-inflow turbine

Taking the transonic nozzle guide vane of a radial-inflow turbine with expansion ratio of 5.0 for an advanced auxiliary power unit as the research object, the vane profile was optimized and cascade tests were conducted by eliminating the local ultrasonic region in front of the throat and weakening the shock wave intensity at the trailing edge. The research showed that by adopting the design idea of large positive incidence angle and small installation angle, and reducing the curvature of suction side before the throat, reducing the flow area of inlet duct, the load in front of the blade profile was improved, the over expansion area before the throat was eliminated, and the airflow acceleration was more uniform. A local concave structure was constructed behind the throat of the suction surface, which can transform one strong shock wave at the trailing edge of the suction surface into two relatively weak shock waves. The peak Mach number decreased, and the adverse pressure gradient at the trailing edge decreased, weakening the strength of the trailing edge shock wave. The test results indicated that the energy loss coefficient of optimized profile dropped as the cascade exit Mach numbers varied from 0.9 to 1.1, and the energy loss coefficient dropped nearly 20% when the exit Mach number was 1.1.