气浮箱型结构纵荡运动水动力系数解析研究

Analytical Solutions of Hydrodynamic Coefficient for Surge Motion by an Air-floating Rectangular Box

基于二维微幅波理论,采用特征函数展开和匹配渐进法建立了气浮箱型结构纵荡运动的解析解,将Matlab程序计算结果与MOSES数值模拟结果进行了对比分析,验证了程序的合理性;进而对不同吃水、不同水深下结构纵荡运动的附加质量系数和阻尼系数的幅频变化规律进行了研究。结果表明：由于未考虑结构内部气体的可压缩性,数值模拟结果大于程序计算结果,MOSES计算结果偏安全;在一定频率区段上,吃水的增加对结构附加质量系数和阻尼系数有显著影响;随着水深吃水比的增加,结构的附加质量系数和阻尼系数呈增大趋势,只有在圆频率为0.65~0.9 rad/s时呈减小趋势,而阻尼系数则呈增大趋势。

The analytic solutions for surge motion of an air-floating rectangular box is obtained by eigenfunction expansionand progressive matching method, based on two- dimensional small amplitude wave theory. Comparative analysis is carried outthrough Matlab program and MOSES to verify the feasibility of the method applied in this paper. And then, the amplitude frequencyof added mass coefficient and damping coefficient are investigated with different water depth-width ratios and different drafts. It isshown that the calculation result of MOSES is safe without considering the compressibility of gas inside the structure; the hydrody-namic coefficients vary significantly in a certain range of frequency with the increase of draft; the added mass coefficient and damp-ing coefficient increase with water depth increasing, only in the frequency range of 0.65-0.9 rad/s, the added mass coefficient de-creased with the increase of water depth.