基于能量的液体火箭中高频POGO振动研究

液体火箭的飞行过程中，火箭结构的振动和推进系统内推进剂流量和压力的脉动存在动力学耦合（POGO），会出现较大的振动响应，甚至失稳。我国的液体火箭工程实践中出现了所谓“40 Hz现象”的中高频POGO振动问题，如何认识中高频POGO振动的机理成为摆在研究者面前一个亟待解决的问题。.针对此问题，本项目从机械能流动和转化的角度出发，建立既保持传统时域方法在计算和仿真方面的优势，又便于反映系统能量关系的数学模型。在此数学模型基础上，开展液体火箭推进-结构耦合系统的瞬态响应分析和模态分析，对液体火箭飞行过程中的能量流动过程进行定量描述。研究POGO振动发生时的能量流动规律和关键物理特征，提出适合于中高频复杂模型的液体火箭POGO振动预判依据。为液体火箭的振动环境设计提供理论参考。

During the flight process of liquid-rocket launch vehicles, dynamical interaction may occur between vibration of the rocket structure and flux-pressure fluctuation of the propulsion system, which may cause large vibration responses, even instability. A medium-to high frequency POGO problem, naming “40 Hz phenomenon” has been discovered in the engineering practice in China, and the study of its mechanism has become an important problem to be solved..Aiming at this problem, this research tries to establish a mathematical model from the aspect of energy flow and transform, which can reflect the energy relationship of the system, at the same time, keep the advantages of traditional time-domain methods in simulation. Transient response analysis and modal analysis of the propulsion-structure coupled system is to be carried out based on this model. We will describe the energy flow process during the flight of the launched vehicle quantitatively. Energy flow regulations and essential physical characteristics in POGO vibration will be studied, aiming to propose a POGO predication criterion. This research may provide theoretical reference for the design of vibration environment of liquid rockets.