Numerical investigation on high-fidelity flow field of an ice-class propeller in ice blockage and cavitation flow

Abstract

Ice-class propellers are prone to generating severe cavitation in ice blockage environments, deteriorating hydrodynamic performance. In this paper, the IDDES method based on hybrid RANS/LES is first applied to research the hydrodynamics, excitation forces, and cavitation of an ice-class propeller in ice blockage and cavitation flow. And the internal influence mechanisms of ice-propeller distance and advance coefficient on the hydrodynamics, excitation forces, and cavitation are analyzed though high-fidelity flow field. The results indicate that the IDDES method performs well, the numerical and experimental errors are less than 3.0%, and the details of induced vortex cavitation are presented. An increase in the advance coefficient leads to a decrease in the mean thrust and torque, which is due to a reduction in the angle of attack. The ice blockage increases the excitation force of the blade behind the ice owing to an increase in pressure on the pressure surface. Meanwhile, ice blockage enhances flow separation, forming a large number of separation vortexes, which become conjoined vortexes under the influence of the propeller. The conjoined vortexes are sucked towards the propeller, forming induced vortex cavitation on the suction surface, and the pressure surface occurs pressure fluctuation. It is also found that the decrease in ice-propeller distance causes a delay in the excitation force. This paper provides a theoretical basis for the hydrodynamic and structural design of ice-class propellers, and offers a reference for the evolution of the flow fields.