三维时域非线性波浪载荷计算方法研究

发布时间：2018-06-13 17:15

本文选题：非线性波浪载荷 + 面元法　；参考：《中国舰船研究院》2016年硕士论文

【摘要】：艏艉部有大外飘的船舶高速航行时,其遭受的波浪载荷呈现明显的非线性。线性势流理论无法反映出这些非线性特性,有必要对非线性势流理论展开研究。诸多文献研究表明,物面变化给载荷带来的非线性是相当重要的,基于此本文采用了一种考虑静水恢复力和入射力非线性的计算方法。该方法将静水恢复力和入射力沿船体瞬时湿表面积分,而辐射力和绕射力沿船体平均湿表面积分。该方法相当程度上反映了载荷的非线性特性,不需要每一时刻重新划分网格,格林函数只需计算一次,计算效率较高。本文采用混合源法求解船体表面的速度势,该方法同时使用了Rankine源与自由面格林函数。Rankine源的计算采用了区分近场和远场的方法;自由面格林函数的计算比较复杂,本文采用了级数/渐进展开的方法进行计算,并给出了具体算例。分别采用时域线性方法、时域非线性方法和WASIM软件对一艘集装箱船和一艘散货船进行了波浪中运动和载荷预报。计算结果表明,小波高下非线性方法和线性方法计算结果基本一致。另外,为了考察大波高下垂向弯矩的非线性,对集装箱船和散货船进行了大波高下的非线性载荷计算,比较发现,舷侧非直壁的集装箱船垂向载荷的非线性比较显著,而舷侧是直壁的散货船垂向载荷非线性较小。本文研究表明该方法能对舷侧非直壁、以较高速航行的船舶开展非线性载荷预报。
[Abstract]:The wave load of the ship with large floating in the bow and stern is obviously nonlinear. The linear potential flow theory can not reflect these nonlinear characteristics. It is necessary to study the nonlinear potential flow theory. Many literature studies show that the nonlinearity of the surface change to the load is very important, based on this paper. A method is used to calculate the nonlinearity of the hydrostatic recovery force and the incident force. This method integrates the static water recovery force and the incident force along the instantaneous wet surface of the hull, and the radiation and diffraction forces are integrated along the average wet surface of the hull. This method reflects the nonlinear characteristics of the load to a considerable extent, and does not need to remesh the grid at every moment, Green. The function only needs to be calculated once, and the calculation efficiency is high. This paper uses the mixed source method to solve the velocity potential of the hull surface. This method uses the Rankine source and the free surface Green function.Rankine source calculation to distinguish the near field and the far field. The calculation of the Green function of the free surface is more complex. This paper adopts the series / progressive expansion. The method is calculated and a specific example is given. The time domain linear method, time domain nonlinear method and WASIM software are used to predict the motion and load of a container ship and a bulk carrier. The calculation results show that the results of the nonlinear method and the linear square method are basically the same. The nonlinear load of the container ship and the bulk carrier is calculated by the nonlinear load of the vertical bending moment of the wave height. It is found that the vertical load of the container ship with non straight side wall is more nonlinear than that of the straight wall, while the vertical load of the straight wall is less nonlinear. Nonlinear load forecasting is carried out for ships at high speed.
【学位授予单位】：中国舰船研究院
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U661

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