围绕自燃推进剂液体火箭发动机燃烧室高频纵向燃烧不稳定现象的随机性进行了深入探讨，分析了结构振动数据在表征燃烧室压力振荡方面的有效性，对比了理论声模态和实测振型，基于蒸发过程作为速率控制的假设，对该燃烧室的稳定性进行了分析，并提出了造成不同供应系统下稳定性差异的2种假设模型。研究表明：由结构振动传感器测得的是燃烧室结构对燃气压力振荡场的响应结果，后者存在一定的频率选择性和非线性；实测突频幅值分布与该频率下的理论声模态基本吻合，确定该燃烧室发生了高频一阶纵向燃烧不稳定现象；线性模型结果表明，该燃烧室具有一定的稳定性裕度，但不能解释系统2条件下燃烧不稳定现象随机出现这一现象；系统2条件下该燃烧室的稳定性恶化或不同工况间的稳定性波动幅值增加，造成部分工况点落入非线性不稳定性区间，成为潜在的不稳定工况。

A thorough investigation was conducted into the randomness of high-frequency longitudinal combustion instability in the combustion chamber of a hypergolic propellant liquid rocket engine. The effectiveness of structural vibration data in characterizing pressure oscillations in the combustion chamber was analyzed， and the theoretical acoustic mode and measured vibration mode compared. Based on the assumption of evaporation as the rate-control process， the stability of the combustion chamber was analyzed， and two hypothetical models proposed to interpret stability differences under different supply systems. Research has shown that： the response of the combustion chamber structure to the gas pressure oscillation field measured by the structural vibration sensor has certain frequency selectivity and nonlinearity； the measured predominant frequency amplitude distribution is basically consistent with the theoretical acoustic mode at this frequency， indicating that the combustion chamber has experienced high-frequency first-order longitudinal combustion instability； the linear model results indicate that the combustion chamber has a certain stability margin； however， it cannot explain the random occurrence of combustion instability under system 2 conditions； under system 2 conditions， the stability of the combustion chamber deteriorates or the amplitude of stability fluctuations between different operating conditions increases， causing some operating points to fall into the nonlinear instability range and become potential unstable operating conditions.