Abstract: In order to investigate the medium frequency coupled oscillation encountered during the storable liquid propellant rocket engine development, the linear frequency-domain models for every component satisfying acoustics analysis were established. By comparing the response of feed system and chamber, and analyzing the natural oscillation complex frequency of the coupled system, the engine system coupled stability at different conditions was estimated. The calculated results accord with the engine test phenomena, by which the characteristics of this kind instability can be described effectively. Moreover, the influence of combustion time lag, injection pressure drop, feed pipe length and throttle orifice on the system coupled instability was discussed. Thus the mechanism of the instability was identified.

Key words: Liquid rocket engine; Medium frequency coupled oscillation; Mechanism analysis; Throttle orifice

摘要： 为了研究常规液体火箭发动机研制中出现的中频流量型耦合振荡问题,对发动机耦合系统中各环节建立了满足声学分析的线性化频域模型。通过比较供应系统和燃烧室的幅频响应,并分析耦合系统的自由振荡复频率,以判断发动机的耦合稳定性。计算结果符合发动机试车规律,能够有效地反映该类型不稳定的特征。进一步讨论了燃烧时滞、喷注压降、管路长度和安装节流圈对系统耦合不稳定的影响规律,并揭示了该类型不稳定的机理。

关键词: 液体火箭发动机;中频耦合振荡;机理分析;节流圈