Impact of Skew Vane Cut on Alternating Stress in a Low Specific Speed Radial Pump Impeller Vane Using Fluid-Structure Interaction (FSI) Simulations

Numerical studies are presented on the pressure pulsations, hydraulic excitation forces and alternative stresses produced in a radial volute pump with high head application. The effect of excitation forces due to Rotor-Stator Interaction (RSI) are evaluated using One-way fluid structure Interaction in terms of alternative stresses on impeller pressure side and suction side. Initially, the pump performance parameters are predicted using steady state Computational Fluid Dynamics (CFD) simulations and compared with the available test data. Due to the transient behavior of pressure pulsations, a transient CFD simulation has been conducted using RANS models to predict the pressure pulsations and its behavior with time on impeller vane outlet and tongue locations. These unsteady pressure distributions are further coupled with the Finite element (FE) model of the impeller to solve and monitor for the stresses induced due to the transient hydraulic loading. To attenuate the alternating stresses produced due to RSI, the geometry of the vane is modified by providing a skew cut with 30° at vane outlet. The pressure pulsation amplitude and stresses are reduced by 10% and 10% respectively for a skew cut of 30° at vane trailing edge.