弹体出水附加质量计算及对阻尼系数的影响分析

Calculation of Added Mass and Its Influence on Damping Coefficient in the Process of Missile Water Exit

给出了水下结构刚体运动、弹性振动引起的附加质量的计算方法;考虑水下结构运动产生的附加质量是随时间变化的量,给出了计及这种变化的结构运动方程,由此得出变化的附加质量所引起的阻尼系数的改变项。在此基础上以弹体出水过程为研究对象,计算了出水过程中结构附加质量随时间的变化情况,同时得出弹体附加质量的变化所引起的阻尼系数的改变量。计算结果表明:附加质量在水深和自由液面附近变化平缓,结构在二者之间运动时变化显著,且由此引起的阻尼系数的改变量不可忽略。

A method to calculate added mass of rigid body motion and elastic vibration of submerged structure was put for- ward. Taking the change of added mass with time into account, the kinetic equations were given, and the damping coefficient in- terrelated with added mass was derived. Taking the missile coming out of water as a research object, the added mass varying with time was calculated, and the change of damping coefficient was gotten resulted from the change of added mass. The calculation results showed that added mass changed smoothly in deep water and around free surface, but it changed remarkably when struc- tures moved from deep water to free surface and as a result, the change of damping coefficient can not be neglected.