Experimental investigation on ice resistance of an arctic LNG carrier under multiple ice breaking conditions

Abstract

In order to investigate the ice loads of an Arctic LNG carrier under different ice conditions, a series of model tests are carried out in an ice tank, the ship model is attached to the towing dynamometer and the resistance force is measured for the specified model speed in level ice, broken ice and brash ice. During the test observations, several phenomena, including the ice-hull interaction modes and the failure modes of ice are captured. Ice loads in level ice and brash ice condition present a characteristic of periodicity, while ice force fluctuated randomly in broken ice because of nonuniform distribution of ice foes. The results also show that ice resistance has a liner fitting relationship with the ship speed. The achievable speed in broken ice condition is almost 3.5 times of that in level ice with the same thickness. With the same thrust power and the same speed, in brash ice condition, the ship can transit the ice 2.7 times thickness of that in level ice condition. Besides, model test results are compared with the results derived from some empirical formulas and the empirical formulas appropriate for resistance estimation in different ice conditions are summarized according to the comparison result. Lindqvist formula is suitable for ice resistance in level ice condition, Zuve & Dobrodeev formula coincides well with the experimental result in broken ice condition, Dobrodeev formula is proper for ice resistance in brash ice condition.