基于混合两步法的船舶砰击载荷预报研究

文章针对船舶结构设计时重点关注的艏部砰击载荷问题,综合考虑计算效率及精度,提出了基于势流理论和计算流体力学方法的混合两步法。第一步,采用三维势流理论预报波浪中有航速船舶的运动响应,分析船波相对运动;第二步,根据预报砰击载荷所在位置的船体横剖面,建立等截面的三维立体模型,采用基于有限体积法与动网格技术的计算流体力学方法,基于第一步得到的相对运动结果模拟落体入水过程,计算砰击压力。使用该两步法预报了某超大型油轮在压载工况顶浪航行时候的艏部砰击压力,并讨论了相对运动和砰击压力的时域历程规律。文中数值预报结果得到了水池模型实验的验证,表明该方法的可行性和预报结果的合理性。

Efficient Simulation of the Slamming Loads Using the Hybrid Two-Step Solution

Slamming will affect ship's structures both locally and globally. Design against slamming load is the concern of ship designers from the view point of strength. For the local slamming problems, it is important to capture both the peak and also the time history of the slamming pressures. One hy-brid two-step solution is proposed with the compromise of the numerical efficiency and the accura-cy.Firstly, the relative motions between the ship and the wave surface are predicted using the poten-tial flow theory for the advancing ship in waves. Then, one 3D segment model is set up using the transverse section with slamming positions.The CFD method using the Finite Volume method(FVM) and dynamic mesh technology is applied to simulate the water entry of this model using the obtained relative motion. The up-rise of the water jet is captured and the local slamming pressures are pre-dicted in time domain. This solution is used to predict the bow slamming loads of one very large crude carrier(VLCC)in ballast condition.The predicted pressure results are compared with those from model tests in irregular waves.Fair well agreements are achieved.