Relation Between Rotational Speeds and Flow Conditions in the Counter-Rotating Type Pumping System

Turbo-pumps have weak points, such as the pumping operation becomes unstable in the rising portion of the head characteristic and / or the cavitation occurs under the low suction head. To overcome simultaneously the both weak points, the authors have proposed the unique pumping system which composed of counter-rotating type impellers and the motor with double rotors. The impeller speeds are self-controlled in response to the pumping discharge. In this paper, the flow conditions around the counter-rotating impellers are discussed experimentally in connection with the rotational speeds.