定常流和振荡流共同作用下半浸没柱体水动力特性实验研究

Experimental investigation on hydrodynamic forces of semi-submerged cylinders in combined steady and oscillatory flow

顺应式的漂浮柔性圆柱型结构物,如深海养殖结构物的浮圈结构、波浪能发电装置的浮体部分等,大多是半浸没的。目前,学术界和工程界对半浸没圆柱的水动力特性了解较少,也使这些新型结构物在设计和分析时面临着载荷输入不确定性的难题。本文通过定常流和振荡流共同作用下半浸没柱体模型实验,开展半浸没柱体水动力载荷特性研究。实验中,由拖车带动半浸没柱体向前运动模拟等效定常流场,强迫柱体以不同振幅和周期振荡来模拟等效振荡流场。实验结果表明,在来流作用下半浸没柱体不可避免会遭受显著的平均升力作用,远大于其所受阻力载荷。研究揭示了水动力系数与多敏感参数的影响关系,确证了KC数对水动力系数影响较弱,总傅汝德数是水动力系数的主控参数,初步建立了流致半浸没柱体水动力载荷系数模型。本文工作可为相关海洋结构物的设计提供有益的指导。

The floating cylindrical structures,such as the floating frame of the fish farming and the floating bodies of wave energy convertor and so on,are generally semi-submerged.However,the investigation on the hydrodynamics on such floating cylinders are few.This status makes the design and analysis of the relevant new structures face the essential problems of the force input uncertainty.The hydrodynamic forces on a semi submerged cylinder were experimentally investigated under the combined influence of steady and oscillatory flow.To simulate the equivalent combined flow,the cylinder towed by the carriage was forced to oscillate with different amplitudes and periods.A significant mean downward lift force was observed for the semi-sub⁃merged cylinders,which was obviously larger than that of the mean drag force.Moreover,the relationship be⁃tween the hydrodynamic coefficients and multi-sensitive parameters was revealed.It is confirmed that the KC number has a weak influence on the coefficients.The Froude number is seen to be the most important parame⁃ter affecting the hydrodynamic coefficients.The empirical models for predicting hydrodynamic coefficients in combined flow are initially developed.This work can provide useful references for the design of the related marine structures and serve as the valuable guideline for future research.