Analysis of Flow Instabilities on a Three-Bladed Axial Inducer in the Fixed and Rotating Frames

The paper describes the results of an experimental campaign performed on a three bladed axial inducer with tapered hub and variable pitch, named RAPDUD. The tests have been performed at the Cavitating Pump Rotordynamic Test Facility at Sitael. S.p.A. under similarity conditions. The tests aimed at characterizing the flow instabilities arising in the fluid elaborated by the inducer at different flow coefficients through two reference frames: a statoric frame by placing pressure transducers on the casing and a rotoric frame by placing the transducers on the inducer hub. The additional reference frame has allowed a better understanding of the flow phenomena arising inside the inducer