Experimental Characterization of the Dynamic Transfer Matrix of Cavitating Inducers

摘要

The present paper illustrates and discusses the first results of the characterization of the dynamic transfer matrix of cavitating turbopumps by means of a series of forced-vibration tests carried out on a high-head three-bladed inducer in the Cavitating Pump Rotordynamic Test Facility (CPRTF) at Alta, Pisa, Italy. The flow has been excited by vertically vibrating with adjustable frequency and intensity the free-surface tank used to close the loop of the suction and discharge lines of the inducer. The pressure and flow rate fluctuations for the determination of the dynamic transfer matrix have been obtained from unsteady pressure measurements at suitable locations on the inlet/outlet lines of the inducer. Two loop configurations with different inlet/outlet impedances to/from the test inducer have been used in order to obtain at each excitation frequency a set of four linearly independent measurements for the detetermination of the four elements of the dynamic transfer matrix. The preliminary results are in qualitative agreement with the scant data available in the literature for comparable inducers.