Abstract

An experimental method for determining the critical pressure perturbations leading to acoustic instability in combustion chambers of liquid-propellant rocket engines has been developed and used to estimate the stability of the working process. The method involves statistical processing of recorded noise pressure pulsations near the natural resonant frequency range for all normal modes of acoustic oscillations in cylindrical combustion chambers and gas generators. The oscillation damping coefficient (decrement), characterizing the difference between the generated and dissipated energy, is used as a diagnostic criterion for predicting the stable or unstable states of a dynamic system. The method is based on the theory of self-oscillating dynamic systems and one-dimensional Markov random processes using the Fokker–Planck–Kolmogorov equation. Analysis of a nonlinear differential equation with a symmetrized stochastic right-hand side describing white noise for experimentally determined amplitudes of pressure pulsations and their statistical processing using Mera software allows the state of self-oscillating systems to be identified as stable or unstable. The method is “passive;" it is applicable without using standard external impulse disturbing devices.

中文翻译：

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基于燃烧噪声的液体火箭发动机燃烧室声振动稳定性极限预测方法

摘要

已经开发出一种确定临界压力扰动的实验方法，该临界压力扰动会导致液体推进火箭发动机燃烧室中的声音不稳定，并被用来估算工作过程的稳定性。该方法包括对圆柱形燃烧室和气体发生器中所有正常声振荡模式的自然共振频率范围附近的记录的噪声压力脉动进行统计处理。表征所产生和消耗的能量之差的振动阻尼系数（减量）被用作诊断标准，用于预测动态系统的稳定或不稳定状态。该方法基于自激动力学系统和使用Fokker-Planck-Kolmogorov方程的一维Markov随机过程的理论。对非线性微分方程进行对称分析，随机对称的右手边描述了白噪声，用于实验确定压力脉动的幅度，并使用Mera软件对其进行统计处理，从而可以将自激系统的状态识别为稳定或不稳定。该方法是“被动的”；它可以在不使用标准外部脉冲干扰设备的情况下适用。