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 paper discusses the implication of these results for full scale propellers operating in iced flows.
The operation of ice class propellers in the extreme wake of nearby ice pieces results in severe cavitation (Walker et aI., 1994; Lindroos and Bjorkestam, 1986). To predict the full scale performance of ice class propellers and the hydrodynamic loading regime to which propellers are exposed during icebreaking operations, loading models must estimate the effects of such cavitation. In an attempt to provide an experimental foundation on which to base such estimates, a project was initiated at the Faculty of Engineering and Applied Science at the Memorial University of Newfoundland (MUN) to examine the hydrodynamic loads associated with non-contact propeller ice interaction. This project was initiated as a result of preliminary work conducted by Memorial University as part of a Joint Research Project Arrangement (JRPA-6) between Canada and Finland, which suggested cavitation resulted in reduced mean hydrodynamic loads but increased vibration and a high risk of cavitation erosion (Walker and Bose, 1994).