碎冰航道中航行船舶阻力数值预报

Numerical prediction of resistance for navigation ships in broken ice channel

北极运输船舶常航行于由破冰船开辟的碎冰航道中;尽管这避免了船舶与层冰碰撞引起的巨大冰阻力,但船舶与航道中碎冰的相互作用受到两侧层冰的影响,进而会对船舶的航行性能产生影响。目前,碎冰航道两侧层冰对船舶航行性能的影响尚未得到充分研究,是否考虑这一影响是北极船舶设计的一个重要问题,采用CFD-DEM(computational fluid dynamics-discrete element method)耦合方法模拟船舶在碎冰航道中的航行过程并分析船-碎冰相互作用特点,进而对船舶阻力进行数值预报。首先,开展了网格和时间步长的收敛性分析以评估数值误差和不确定度,验证了数值模型的可靠性;在此基础上的预报结果表明,由于两侧层冰对船舶兴波产生影响,船舶水阻力随航道宽度的减小而小幅增大且主要为压阻力的增加;船舶冰阻力随航道宽度的减小而迅速增大,船体两侧的碎冰堆积现象是导致冰阻力增大的主要原因。

Arctic transport ships often sail in broken ice channel opened by icebreakers.Although this avoids huge ice resistance caused by collisions between ships and layer ice,interaction between ships and broken ice in channel is affected by layer ice on both sides,it in turn can have an impact on navigation performance of ships.At present,effects of layer ice on both sides of broken ice channel on navigation performance of ships has not been fully studied,whether or not to consider these effects is an important issue in arctic ship design.Here,computational fluid dynamics-discrete element method(CFD-DEM)coupled method was used to simulate navigation process of ships in broken ice channel,and analyze characteristics of ship-ice interaction to make numerical prediction of ship resistance.Firstly,convergence analysis of mesh and time step was performed to evaluate numerical errors and uncertainties,and verifythe reliability of numerical model.The prediction results showed that due to effects of layer ice on both sides on ship’s wave-making,ship’s water resistance slightly increases with decrease in channel width,and it mainly is increase in pressure resistance;ice resistance of ships increases rapidly with decrease in channel width,and accumulation phenomena of broken ice on both sides of ship is the main reason for increase in ice resistance.