5th International Offshore and Polar Engineering Conference, June 11-16, 1995, The Hague, The Netherlands
cavitation; blockage; ice; hydrodynamics
Operation of a propeller in ice covered waters results in severe loading on the propulsion system. Model tests have shown that non-contact hydrodynamic loads on the propeller are of nearly the same magnitude as contact loads between the propeller and ice pieces in the form of impacts and milling of ice. Recent experiments in the cavitation tunnel of the University of Tokyo were conducted with an open propeller operating in a milled recess of a simulated ice block mounted on an instrumented load cell. Measurements of thrust and torque from the propeller, obtained using an electronic dynamometer, showed cavitation resulted in a reduction in the mean value of both thrust and torque over a greater range of advance ratios than has been found in previous published experiments. The results suggest that cavitation reduces the non-contact hydrodynamic loads. The paper discusses the implication of these results for full scale propellers operating in ice flows.