APP下载

误差激励作用下三维矩形液舱晃荡数值仿真

2016-10-29陈世文杨志勋杨钰城阮诗论岳前进

计算机辅助工程 2016年4期

陈世文 杨志勋 杨钰城 阮诗论 岳前进

摘要: 原始激励的随机小幅变化会对晃荡载荷造成不确定影响,往往具有较强的随机性和非线性现象.通过计算流体力学(Computational Fluid Mechanics,CFD)方法构造三维矩形液舱载液率为85%的晃荡数值模型,并基于相同条件开展模型晃荡实验;通过追踪自由表面变化和晃荡冲击压力时程比较分析验证数值模型的有效性.基于原始激励构造一定误差变化范围(2%,5%和10%)内的误差激励,通过数值模拟分别提取拐角监测位置处的晃荡载荷时程曲线.研究结果表明:在不同误差激励下,虽然晃荡波形和频率基本一致,但压力峰值偏差与误差大小不呈现正相关效应,最大偏差约为33.17%;微小激励误差有可能对晃荡载荷结果造成较大的偏差影响.

关键词: 液舱; 液体晃荡; 误差激励; 冲击压力; 数值模拟

中图分类号: TE53; TB115.1文献标志码: B

Abstract: The radom slight change of original excitation would cause uncertain effect on sloshing load, which leads to strong stochastic and nonlinear phenomenon. A numerical model at 85% filling level is built for a 3D rectangle tank by Computational Fluid Mechanics (CFD) method, and the sloshing test is performed for the models under the same conditions; by comparing the free surface change and the time-history of sloshing impact pressure, the validity of the numerical model is verified. The error excitations with certain value (2%,5% and 10%) are given from the original excitation, under which the time-history curves of sloshing load of the detecting zone of the up-corner are obtained. The research results indicate that, there are similar sloshing wave form and frequency under different error excitation, but the deviation of pressure peak would not present positive correlation effect with error magnitude, and the maximum difference value is 33.17%; moreover, a slight excitation error would cause higher change of sloshing impact pressure error.

Key words: liquid tank; liquid sloshing; error excitation; impact pressure; numerical simulation

0引言

液体晃荡是一种非常复杂的流体流动现象,且具有很强的非线性和随机性.晃荡是普遍存在的一种自然现象,在海洋、船舶、航天和能源等工程领域也均有涉及,特别是在液化天然气行业.近年来由于浮式生产储油船和超大油船的装载量越来越大,伴随的晃荡冲击问题越来越严重.液舱在不同海况激励条件下的晃荡载荷成为液舱设计的一大难点和关键考虑要素.

影响晃荡载荷的因素较多,例如外激激励、载液高度及流体的物理特性(可压缩性、黏性和密度)等.不同的外激激励对晃荡载荷影响较大.THIAGARAJAN等……

登录APP查看全文