密度分层液体晃荡非线性相互作用机理研究

Study of nonlinear interaction mechanism of density stratified liquids sloshing

基于振动台试验研究了水平激励下的密度分层液体晃荡,利用Morlet小波变换和小波二阶相关谱分析了密度分层液体晃荡的非线性作用.Morlet小波变换显示界面波最大波高和最大晃荡压力发生在强非线性相互作用的时间段内,当外激励频率远离理论固有频率时,只在密度分层液体晃荡初始时间段内发生较强的非线性相互作用,当外激励频率等于固有频率时,非线性相互作用程度随着时间推移越来越强.小波二阶相关谱呈现的Morlet小波变换中出现的频率变化表明,当外激励频率等于固有频率时密度分层液体晃荡的非线性相互作用程度最强,其程度在小波二阶相关谱中接近1.当外激励频率远离固有频率时,界面波频率成分之间也有相当程度的非线性相互作用(bw>0.5).

The horizontal sloshing of density stratified liquid was tested on a shaking table,and the nonlinear interaction of density stratified liquid sloshing was studied by Morlet wavelet transform and wavelet-based bicoherence spectra.Morlet wavelet transform results show that the maximum wave height and maximum sloshing pressure of the free interface wave occur during the period of strong nonlinear interaction.When the external excitation frequency is far away from the theoretical natural frequency,strong nonlinear interaction occurs only during the initial period of the stratified liquids sloshing.When the external excitation frequency is equal to the natural frequency,the degree of nonlinear interaction becomes stronger with time.The wavelet-based bicoherence spectra provide a basis for the frequency changes in the Morlet wavelet transform,and the results show that the strongest degree of nonlinear interaction is when the external excitation frequency is equal to the natural frequency,and its degree in the wavelet-based bicoherence spectrum is close to 1.When the external excitation frequency is far away from the natural frequency,there is a considerable degree of nonlinear interaction between the frequency components of the free interface wave(bw>0.5).