Blade Rows Interaction of Contra-Rotating Axial Flow Pump in Pressure Field on Casing Wall

An application of contra-rotating rotors has been proposed against a demand for developing higher specific speed axial flow pump with more compact structure, higher efficiency and higher cavitation performance. The blade rows interaction between front and rear rotors should be taken into account in pump design for stable operation and reduction of unsteady losses. The measurements of static pressure distributions on casing wall with the phase locked sampling method are carried out for two types of the rear rotors. In the present paper the difference of the rear blade interaction and the unsteady pressure fluctuation are clarified. The pressure fluctuations are more remarkable in the front rotor than in the rear rotor and they are caused by rear rotor pressure field. The effects of pressure fluctuations will be discussed in more details toward understanding the blade rows interaction in the contra-rotating axial flow pump.