EXPERIMENTAL STUDY OF THE ICE BREAKING RESISTANCE ON AN AIR CUSHION PLATFORM

The ice breaking processes of an air cushion platform were investigated and the corresponding resistances were also measured through model tests performed in ice tank. An actual ice-breaking air cushion platform that is in-service was modelled during the tests, and a reasonable similarity law was established. By obeying the similarity law, each part of the actual platform was simulated, including the structural frame, air ducting, air cell and the cushion system and thus, structural shape and cushion mechanism of model platform was kept in similar with the prototype platform. During the tests, the model platform was towed by the main carriage passing through the model ice sheet with different hover-heights and navigation speeds. The ice breaking process was investigated under each test condition. By analyzing on the test phenomena and measured results, the ice breaking process was deeply discussed and, the ice breaking mechanism was revealed for the air cushion platform. It could be found that the non-full-cushioning condition is more beneficial to the ice breaking operations for the model platform through model tests. The key ice breaking mechanism of an air cushion platform was that a stable air space is formed under the ice sheet. Thereby the ice sheet was pressed down by the model platform and risen upward by the air space, and then the bending failure of the ice sheet occurred. The ice breaking wind pressure of an air cushion platform varying with the structural attitudes was tested during the model tests. Afterwards, the ice breaking wind pressure was analyzed in time and frequency domain respectively, and the regularities of ice breaking wind pressure varying with the navigation speed were discussed. The regularities of ice breaking resistance varying with the hover-height and navigation speed were finally established as the necessary basic data for guiding the structural design and operating control of such type of platform in practice.