Experimental study on friction coefficient correction method for model scale testing in brash ice channel

Abstract

Maritime traffic in the polar regions has been surged in recent years due to a decrease in ice-covered areas. Climate change plays a pivotal role in contracting the ice thickness, which escalates the trade through the northern sea route. Navigation of icebreaker across uniform ice creates a broken channel in level ice. The recurrence of ships maneuvering through this broken channel causes the ice pieces to break and refrozen repeatedly, forming the brash ice channel. This channel is used by other ships as it offers less resistance than level ice. The resistance offered by brash ice channel is studied at model scale in this research.

Model scale tests can be used to verify the performance of vessel before building a prototype. Model scale tests are economical and easily manageable compared to full-scale tests. In model scale testing, often, test parameters deviate from the target values. To recoup this situation, test results are corrected according to specific techniques. In the ice model test, deviation in friction coefficient between ship hull and ice is corrected using Finnish-Swedish Ice Class Rules (FSICR). This thesis aims to improve the friction coefficient correction method in brash ice channels using model scale tests.

In this study, a simplified ship model is designed and manufactured. Paints of three different friction coefficients are used for brash ice tests. Brash ice channels are prepared according to the International Towing Tank Conference (ITTC) guidelines. Before brash ice channel tests, Ice-hull friction coefficients of each paint are measured. Two bow shapes (Round and Wedge) are tested in a brash ice channel. Total resistance, as well as its components, are measured during the test.

Results from the tests are verified using ice resistance models developed in earlier research. These ice resistance models are developed using theoretical and experimental knowledge. Then, a new friction coefficient correction formula is proposed based on tests results.