Experimental study of hydrodynamic performances of pre-swirl pumpjet propeller

A pre-swirl pumpjet propeller(PJP) is widely used in the new generation of quiet submarines all over the world, although the experimental study of its hydrodynamic performances is still rare. This paper carries out experimental tests of the pre-swirl PJP with a 9-blade stator and a 7-blade rotor in a cavitation water tunnel. The thrust coefficient and torque coefficient of the pre-swirl PJP in open water are tested with a force measurement device, and the wake flow field of the pre-swirl PJP is tested with a laser particle velocimetry system. The experimental results show that the rotor thrust coefficient, stator-duct thrust coefficient and rotor torque coefficient of the pre-swirl PJP decrease with increasing the advance coefficient J, but the absolute value of the torque coefficient of the stator-duct thrust increases with increasing J. The open water efficiency of the pre-swirl PJP reaches the maximum when J=1.0, being 61.91%. The thrust of the pre-swirl PJP is mainly provided by the rotor. In addition, the wake flow field of the pre-swirl PJP is composed of jet acceleration zone, hub low-speed zone and mixed zone. The transient velocity and average velocity in the wake flow field under different working conditions are obtained.