Numerical Simulation and PIV Experimental Investigation on Underwater Autorotating Rotor

In this work, the flow field of an autorotating rotor in a water tunnel with various pitches and shaft backward angles was investigated via particle image velocimetry (PIV). The experiments were carried out on a free-rotating two-bladed single rotor. Computational Fluid Dynamics (CFD) based on moving overset grids were developed to study the hydrodynamic characteristics of an underwater autorotating rotor. The simulation results are in good agreement with the test results. The thrust and thrust coefficient of the underwater autorotating rotor were calculated by CFD simulation under different situations. The research demonstrates that rotational speed and thrust have a significant positive correlation with water velocity, pitch, and shaft back angle. In particular, the thrust coefficient scarcely varies with the shaft backward angle. An underwater autorotation rotor with a thin airfoil, negative torque, and a suitable number of blades can increase the thrust and thrust coefficient. The investigation is of significance in enriching the autorotation theory of rotors and helping to develop underwater autorotating rotors.