极地吊舱推进船舶回转性能的离散元分析

吊舱推进装置在极地船舶中被广泛应用，其转舵模块可以带动螺旋桨摆动从而产生任意方向的推进力，使船舶操纵更为灵活。提出了一种吊舱推进船舶冰区操纵的离散元方法，对具有吊舱推进装置的冰区船舶破冰过程进行了数值模拟。以“雪龙2”号破冰船为研究对象，计算分析了船舶定速直航时的冰阻力，并通过与Lindqvist经验公式的对比验证了冰阻力计算的合理性。在此基础上进一步对船舶在不同冰厚、不同吊舱转向角下的回转破冰运动进行了离散元模拟，分析了回转半径与船长比值随冰厚的变化规律。计算结果表明：船舶的回转性能随冰厚的增大而降低，并随吊舱转向角的增大而显著提高。

Turning ability of pod-driven polar ship based on discrete element analysis

The pod-propulsion systems are widely applied in polar ships. The steering module in pod can drive the propeller to swing and generate thrust in any direction, and improve the maneuvering capability in ice covered regions. In this paper, a discrete element method (DEM) for maneuverability of a pod-driven ship in ice covered region is proposed, and used to simulate numerically the ice-breaking process of a pod-driven icebreaker. Taking the Icebreaker Xuelong 2 as an example, the ice resistance of the straight-line navigation at a constant velocity is calculated with DEM. Compared with the ice resistance analyzed with the Lindqvist Formula, the rationality of ice resistance simulated with DEM is validated well. The ice breaking motions under different ice thicknesses and pod''s deflections are also simulated with DEM, and the ratio between the turning circle radius and the ship length is analyzed. The simulated results shows that the turning ability of ship decreases with the increase of ice thickness, and improves with the increase of the pod''s deflection.