11th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
The flow in a radial-inflow turbine composed of a vaned stator and a centripetal impeller is studied thanks to steady-state and unsteady numerical simulations in order to identify the aerodynamic structures that are potential acoustic sources and guide the development of an acoustic analytical model. The main flow structures and secondary flows are first identified, and then linked to blade and vane surface-pressure fluctuations. The rotor-stator interaction is identified as the main potential acoustic source. The tip leakage flow is studied in details and appears only of secondary importance at this operating point. The two main rotor-stator interaction mechanisms are : the impact of the stator wakes on the impeller blades, and the brushing of the shock attached to the stator trailing edge on the impeller blades.