Effect of Tip Clearance of the Perfomance of a Three-Bladed Axial Inducer

This paper illustrates the results of an experimental campaign conducted in the Cavitating Pump Rotordynamic Test Facility. Tests have been carried out at two values of the blade tip clearance on the three-bladed DAPAMIT03 inducer, designed by means of a reduced-order model, with geometry and noncavitating performance representative of typical space rocket inducers. Different cavitating behaviors have been observed at different values of the blade tip clearance, particularly near breakdown conditions. The intensity of pressure oscillations tends to decrease as the tip blade clearance increases, and cavitation-induced azimuthal flow instabilities appear to be more sensitive to changes of the blade tip clearance than axial flow instabilities