对于液体运载火箭纵向振动的稳定性分析，在建立贮箱内液体的振动模型时，不仅需要考虑结构的弹性特性，还需要考虑液体晃动时的阻尼特性。由于模态阻尼比与一个振动周期内阻尼力做功、平均机械能及模态固有频率相关。因此可以先通过结构与液体的耦合振动分析确定其模态，进而分别计算液体与结构接触面、自由面以及液体内部阻尼力做功，同时计算平均机械能，从而得到模态阻尼比。在计算模态阻尼比时，对耦合振动的模态分析、液体内部流场计算均采用等效比拟的方法，为充分利用通用程序计算创造了条件。此方法不仅能够提高效率，同时也便于工程上的应用。%When conducting the stability analysis for longitudinal vibration of a liquid-carried rocket and establishing the vibration model of liquid inside the tank,the elastic characteristics of the structure should be considered, the damping character of liquid shaking should also be considered.Due to the fact that a modal damping ratio is correlated to the work of damping force per vibration period,mean mechanical energy,and the modal natural frequency,the fluid-structure coupled vibration modes were determined via analyzing the coupled vibrations of structure and liquid,and then the works done by the damping force on the contact surface between liquid and structure that on the free surface and the inner damping force were calculated,the mean mechanical energy was also computed,so as to achieve the modal damping ratio.The heat flux analogy method was adopted in the modal analysis of coupled vibration and the calculation of liquid inner fluid-field to take full advantages of a general program.This method not only improved the efficiency,but also facilitated engineering applications.
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