Abstract
An application of contra-rotating rotors, consisting of front and rear rotors rotating in the opposite direction each other, has been proposed against a demand for developing higher specific speed axial flow pump with more compact structure, higher efficiency and better cavitation performance. Air/water two-phase flow performance of contra-rotating pump has to be, also, investigated as axial flow pumps are used for standby operations of air-lock and air/water mixing discharge to prevent floods. In the present paper, experimental results on air/water two-phase flow performance of test pump of contra-rotating rotors (RR1 Type) are shown and compared with those of conventional axial flow pump, consisting of a front rotor and a rear stator. Effects of changes of rear rotor rotational speed, which is an advantage of contra-rotating axial flow pump, on two-phase flow performance of RR1 type are discussed. It is shown that air/water two-phase flow performance of contra-rotating axial flow pump is capable to be improved by this control procedure for rear rotor rotational speed.
