多孔挡板影响液体晃荡冲击压力特征的研究

Effects of Porous Baffle on Characteristics of Liquid Sloshing Impact Pressure

船舶波浪中航行激励液舱内液体晃荡产生的激振力会导致液舱结构局部失效,从而影响船舶运动姿态,而多孔挡板可以有效避免该问题。构建了大振幅水平激励试验平台以探讨冲击压力对频率的响应规律,分析了多孔挡板在不同激励频率下冲击压力的时域和频域特征,并从挡板结构和涡旋强度方面解释冲击压力特征产生差异的原因。结果表明,大振幅激励下的波浪翻卷、破碎等非线性特征会导致共振频率偏离固有频率;多孔挡板能够降低液体晃荡冲击压力的峰值与峰宽,且在一阶固有频率处压力峰值降低率更显著;多孔挡板不改变幅频中的主频成分,时频谱中仅有能量较低的低频成分;多孔挡板的固体结构阻碍行进波中大部分流体运动,剩余小部分流体通过孔隙会产生涡旋运动,从而耗散能量,减缓流体对液舱壁面的冲击。

The liquid sloshing in the tank was excited by ship navigation in waves.The exciting forces would cause local damages to the tank structure and affect the ship’s motion attitude,which might effectively avoid by the porous baffles.A large-amplitude horizontal excitation test platform was constructed to discuss the response laws of impact pressure to frequency.The time domain and frequency domain characteristics of impact pressure were analyzed under the influences of porous baffles at different excitation frequencies.The reasons for the difference of impact pressure characteristics were explained from the aspect of baffle structure and vortex strength.The results show that the nonlinear characteristics such as wave overturning and breaking under large amplitude excitations will lead to the deviation of resonance frequency from natural frequency.The porous baffle may reduce the peak value and peak width of liquid sloshing impact pressure,and the reduction rate of pressure peak value is more significant at the first natural frequency.The porous baffle does not change the primary frequency component in the amplitude-frequency,and there is only a low-frequency component with low energy in the time spectrum.The solid structure of the porous baffle blocks most of the fluid movement in the traveling wave,and a small part of the remaining fluid will produce vortex movement through the pores to dissipate energy and slow down the impact of the fluid on the liquid bulkhead surfaces.