| Résumé | This paper presents the results of resistance and propulsion tests in level ice of a 1:20 scale model of the Canadian Coast Guard R-class icebreaker at two ice-hull friction coefficients, performed at several ice testing facilities in various countries under the aegis of the Committee on Performance of Ships in Ice-covered Waters of the International Towing Tank Conference (ITTC). There is good agreement overall among the test results obtained at the various facilities. The differences that do remain should be attributed to differences in experimental techniques and types of model ice used at the participating laboratories. An increase in hull roughness led to an increase in ice resistance as expected, but had no effect on the propeller characteristics. While the thrust coefficient in ice was nearly the same as in clear water, the torque coefficient and thrust deduction factor were much greater in level ice than in clear water and nearly constant. Full-scale ship performance predicted from the resistance test results of the rougher model and the propulsion characteristics in clear water was in good agreement overall with available field trial data. Predicted performance using the ice resistance of the rougher model and the model propeller characteristics in ice was usually below that observed at full scale. This would indicate that ice-propeller interaction is excessive during model propulsion tests, or that the effect of ice entrainment on propeller performance is greater at model scale than at full scale. Ice-propeller interaction remains a domain where further research is needed. |
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