Cavitation Performance of Low Speed Ice-Classed Propeller

Abstract

In the ice breaking condition, on account of the low speed and heavy propeller load, the ship resistance is large, which will aggravate the propeller cavitation and the propeller-induced pressure. In this paper, the cavitation performance of the ice-classed propeller is analyzed by numerical simulation and model experiment. Commercial CFD software was used for the numerical simulations, in which the cavitation flow is solved by Schneer & Sauer cavitaiton model based on a single-fluid multiphase mixture flow approach. Model tests to measure cavitation flow on an ice-classed propeller were carried out in SSSRI K15 Cavitation Tunnel. The size of the test section of SSSRI K15 Cavitation Tunnel is 600mm*600mm. The propeller performances in uniform flow over a range of advance coefficients were carried out in open water test in a towing tank. The diameter (D) of the model propeller was 248mm in this research. Firstly, the open water performance of propeller is numerically studied. Near the design conditions, the numerical results are almost consistent with the test results, with an error of less than 1%. In the case of ice breaking, the blocking effect of ice in front of a propeller is studied. The experiment results show that with the ice block close to the propeller, one or more vortex tube structures are generated between the propeller blade and the ship bottom while the vortex cavitation occurs. Such phenomenon is also found between the propeller and the ice block. When the blocking effect is significant, the stable vortex tube structure will appear and significantly change the cavity shape near the blade. When the distance between the ice and the blade disc exceeds 0.72D, the vortex tube structure will disappear.