Ice Resistance Tests on Two Models of the WTGB Icebreaker,
COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
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For the particular full-scale conditions modelled in the tests, the dimensionless level ice resistance obtained with the two models of the 140-foot WTGB was essentially independent of the model scale. The fact that no scale effects were identified in the present tests can be interpreted in two ways one is that icebreakers of size and operating conditions in ice similar to those of the WTGB can be confidently model tested at a scale of at least 124. The second interpretation is that model tests of icebreakers may be conducted in model ice 2 cm thick or thicker andor with a bending strength of 30 kPa or more, since these values were the test conditions for the smaller WTGB model these tests conditions would then specify a limiting model scale so that they correspond to the desired operating conditions of an icebreaker under design. By conducting model tests not only in level ice but also through broken ice channels, it was possible to separate the level ice resistance into two main components. According to this analysis, it was shown that the ice-breaking component is primarily a function of the Cauchy number but also the Froude number, especially at speed low enough for the ship to experience significant pitching and heaving motions when riding on the level ice and falling back as the ice sheet fails.