HYDRAULIC CHARACTERIZATION OF CENTRIFUGAL PUMPS IN HE-I NEAR SATURATED CONDITIONS

The hydraulic characteristics of a variable speed liquid helium centri fugal pump in He near saturated conditions (4.2 K and similar to 100 k Pa) are presented. Three different housings are tested, a simple impel ler housing and two housings with an impeller with an associated screw inducer, to investigate the effect of the inducer and the effect of t he diffuser throat diameter dimension on the performance of the pump. The three housings have been tested in an open loop without discharge line. The pressure difference across the pumps and the mass flow rates have been recorded for different pump speeds. We compare the pump per formances with predicted values. For different inlet tube length, cavi tation effects, that might occur near saturated conditions, were also investigated. (C) 1998 Elsevier Science Ltd. All rights reserved.