跨介质运动物体的附加质量

跨介质运动物体具备能够适应多种流体介质环境的突出优势,但由于受自由面及流体影响,力学环境复杂,其运动特性难以预测。附加质量法是工程上解决物体与流体耦合问题的常用方法,但现有的附加质量结论无法直接推广到带自由面问题的跨介质过程。针对跨介质过程的时变附加质量问题,提出了一种新的求解方法,研究了不同浸深时某柱体外形跨介质过程中出水阶段和入水阶段的附加质量变化规律。结论表明:出水阶段和入水阶段的附加质量随浸深的变化趋势一致,曲线相似;相同浸深状态时出水阶段和入水阶段的法向附加质量相近,线性特征明显;相同浸深状态时出水阶段和入水阶段的轴向附加质量、附加转动惯量和附加静距差距明显,2个过程不可逆。本文所提出的方法可为各类跨介质结构体设计提供技术支持,也可推广至其他带自由面问题的附加质量求解中。

Added mass of trans-media moving object

Trans-media moving object was equipped with outstanding advantages in multiple fluid media environment. However, its moving characteristics were hard to predict because of the free surface problem and complex stress. Added mass method was common to solve fluid-structure coupling problems in engineering, but the existing conclusions could not be extended to trans-media process with free surface. A new method was proposed aiming to solve the time-varying added mass problems in trans-media process. Changing laws of added mass of some cylinder were studied, which lied in different depths in both separation step and entry step of the trans-media process. It is shown that the two steps have same changing trend and similar depth-varying curve with the depth varying; in the same depth, normal added mass of separation step is near to that of the entry step and both depth-varying curves have linear characteristics; as for axial added mass, added inertia moment, and added static moment, the results of two steps in the same depth are different obviously, so the two steps are irreversible. The proposed method is helpful for design of trans-media structure, and can be extended to other situations of added mass computing with free surface.