随机激励下液舱晃荡数值模拟分析

Numerical simulation analysis of liquid sloshing in tank under random excitation

[目的]研究随机激励条件下矩形液舱内的瞬态效应、不同谱峰频率与有义激励振幅对液舱晃荡的影响。[方法]采用计算流体力学(CFD)方法建立数值模型,通过与线性势流解析解和实验数据进行对比,验证所提数值模型的可靠性。[结果]结果显示,随机激励瞬态效应对液舱晃荡自由水面变化有显著影响,通过施加缓冲函数可以较快地获取稳定结果;当激励谱谱峰频率接近液舱晃荡固有频率时,液舱晃荡波高响应谱的能量主要集中在液舱的固有频率处,而当激励谱谱峰频率远离液舱晃荡固有频率时,液舱晃荡波高响应谱的能量主要集中在谱峰频率附近;随着激励谱有义振幅的增大,液舱晃荡响应相对于线性波(偏离度为0)其振幅偏离度增大,液舱的非线性显著增强。[结论]对于随机激励的模拟,尤其是激励频率远离固有频率时,对激励历时线进行缓冲函数处理非常有必要;当谱峰频率远离一阶固有频率向更高频移动,在接近第i阶固有频率时,该频率处的峰值将占主导。

[Objectives]This paper studies the transient effects,different frequencies of spectral peaks and meaningful excitation amplitudes on liquid sloshing.[Methods]A numerical model is established using the computational fluid dynamics(CFD)method,and the reliability of the numerical model is validated through comparison with the analytical solution of linear potential flow and experimental data.[Results]The transient effects of random excitation have a significant influence on the fluctuation of the free water surface of liquid sloshing in the tank.By applying the buffer function,stable results can be obtained quickly.When the peak frequency of the excitation spectrum is close to the natural frequency of the tank,the energy of the waveheight response spectrum of the liquid sloshing in the tank is mainly concentrated at the natural frequency of the tank.When the peak frequency of the excitation spectrum is far from the natural frequency of the tank,the energy of the wave-height response spectrum is concentrated near the peak frequency.With the increase of the meaningful amplitude of the excitation spectrum,the amplitude deviation of the liquid sloshing response relative to the linear wave(the deviation degree is zero)increases,and the nonlinearity of the tank increases significantly.[Conclusions]For the random excitation simulation,especially when the excitation frequency is far from the natural frequency,it is necessary to buffer the excitation duration.It is found that when the peak frequency of the excitation spectrum moves away from the first natural frequency to higher frequencies,the energy is dominant at the i-th order of the natural frequency when the peak frequency is close to it.