双浮体自由垂向振荡响应特性  

Heaving-motion response of two freely floating vertical cylinders

作　　者：吴必军[1] 胡城[1] 郑永红[1] 游亚戈[1] 

机构地区：[1]中国科学院广州能源研究所,广东广州510640

出　　处：《水动力学研究与进展（A辑）》2006年第4期458-464,共7页Chinese Journal of Hydrodynamics

基　　金：国家十五863计划项目(2001AA516010);中科院知识创新工程重要方向项目(KGCX2-SW-305)

摘　　要：双圆柱体系统在波能装置和防波构件中得到应用,该系统是一个多自由度受迫阻尼振荡系统,阻力和激励力都来自于波浪力。本文采用线性波理论和特征函数展开皮配法,在平面入射波条件下,求解了双圆柱体垂荡运动辐射速度势和圆柱体固定不动时的绕射速度势,推导了附加质量、阻尼系数、波浪激励力表达式,列出了浮体垂荡运动微分方程。最后讨论了下浮体尺度及位置对系统响应特性的影响。数值计算表明无论下浮体尺度及位置如何变化,它只影响到浮体垂荡响应在低频端的值,下浮体的振幅值总是小于入射波的振幅值,而且它在一个较窄的频率范围内从较大的值很快变化接近于零。下浮体半径与上浮体半径之比的变化不仅影响到两个浮体的响应幅值,而且也影响到曲线的变化趋势;两浮体距离的变化对曲线的变化趋势影响不大,但对曲线的幅值有影响;下浮体厚度的变化只少许改变了响应曲线的幅值。The system consisting of two freely floating circular cylinders has been applied to wave energy conversion devices or breakwaters. This is a forced damped oscillating system; which has multi degrees of freedom. The damping and driving forces come from wave forces. By use of the linear potential theory and the method of matched eigenfunction expansion, analytical expressions for the potentials due to diffraction in the presence of an incident wave acting on fixed structure and radiation by heaving motion on calm water are obtained. A set of theoretical added mass, damping coefficient and exciting force expressions have been proposed. The heaving motion equation of the system is given. Finally, Numerical results are presented which illustrate the effects of the various geometrical parameters of the lower cylinder and the various distances between two cylinders on the response. It is found that the size of the lower cylinder and the distance between two cylinders only influences the response at low frequency range. Numerical results show that the amplitude of the lower cylinder is always smaller than that of the incident wave, and in a narrow range of frequencies, the amplitude of the lower cylinder from relatively large values sharply decreases approaching to zero. It is found also that the change of the ratio of the lower cylinder＇s radius to the radius of the upper cylinder not only leads the amplitude of the response to vary, but also changes the varying tendencies of the response. The distance between two cylinders influences the values of the response. The influence on the response is not obvious by the thickness variation of the lower cylinder.

关 键 词：受迫阻尼振荡系统 速度势 响应 

分 类 号：O353.1[理学—流体力学]