有限潜深状态下圆柱壳固有振动特性分析

Natural vibration characteristics analysis for an immersed cylindrical shell with a limited diving depth

基于波传播法和虚源法,建立有限潜深状态下圆柱壳-声场耦合数学模型,并考虑了自由液面和流体静压的影响。采用数值方法求解耦合系统特征方程,得到了有限潜深状态下圆柱壳的模态频率。数值分析表明:较无限域中圆柱壳模态频率特性而言,自由液面的存在致使结构模态频率相应增大,而流体静压则使得结构模态频率相应减小;当潜深较小时,自由液面的影响相对较显著,而当潜深较大时,流体静压的影响相对较显著;流体静压对有限潜深状态下圆柱壳各阶模态频率特性的影响程度不尽相同,从而导致在一定潜深条件下,圆柱壳模态频率阶次出现变化;当潜深较大时,圆柱壳面临失稳。

Based on the wave propagation approach and the image source method,the dynamic model of a cylindrical shell with a limited diving depth coupled with a sound field was established considering both effects of free surface and hydrostatic pressure. The coupled system's characteristic equation was solved with the numerical method and the modal frequencies of the cylindrical shell with a limited diving depth were obtained. The numerical analysis showed that comparing with modal frequency features of a cylindrical shell in an unlimited field,free surface makes the structure's modal frequencies increase,while hydrostatic pressure makes them decrease; when the diving depth is smaller,the effects of free surface are more significant; when the diving depth is larger,the effects of hydrostatic pressure are more significant; the effects of hydrostatic pressure on the structure's various modal frequencies are different to cause the order of modal frequencies to change under the condition of a certain diving depth; when the diving depth is larger,the shell may be unstable.