Experimental Study on Rotational Speed Control of Contra-Rotating Axial Flow Pump

Abstract

An application of contra-rotating rotors, in which a rear rotor is in tandem with a front one and these rotors rotate in the opposite direction to each other, has been proposed for higher specific speed axial flow pump. Then the superiority of efficiency and cavitation performance of contra-rotating type has been clarified from experimental comparison with the conventional type in addition to the difficulty of high performance design of it. In the present study, the possibility of performance improvement of contra-rotating axial flow pump by rotational speed controls of front and rear rotors were experimentally investigated. The substantial improvement of pump efficiency was achieved from the partial to the over flow rate by the rotational speed control of rear rotor and was achieved at the lower flow rates by that of front rotor.