Abstract: For the first longitudinal pressure oscillation spontaneously occurred in the preburner and feed system during engine hot test, the linear transfer matrix models for every component satisfying acoustics analysis were established, including liquid pipe model, open swirl injector dynamic model, flow regulator model, smooth burnout curve combustion model and one dimensional distributed parameter gas flow model, et al. The amplitude frequency characteristics of preburner under fluctuation of propellant flow rate were calculated, as well as the injection admittances of liquid oxygen and kerosene feed system. The coupled stabilities of preburner-feed system under different conditions were researched by Nyquist stability criterion. The computation results agree with the engine test phenomena. During the medium frequency range, preburner pressure has high response amplitude both for kerosene and liquid oxygen flow rate disturbance, and kerosene flow rate disturbance creates evident entropy wave amplitude. Due to large volume of liquid oxygen main manifold, oxygen injection admittance has high amplitude in wide frequency rarge, and is much larger than the kerosene injection admittance during the range of 600~800Hz. The mechanism of medium frequency coupled instability for preburner and feed system is coupling between the liquid oxygen feed system outlet flow rate oscillation with the first longitudinal acoustic oscillation in preburner. Decreasing of the oxygen injection pressure drop and the engine thrust throttling both have disadvantaged influence on the coupled stability. Increasing the oxygen injection pressure drop will reduce the liquid oxygen flow rate feedback and improve the coupled stability of the system. 

Key words: Oxidizer-rich preburner; Feed system; Amplitude frequency response; Coupled stability; Acoustic oscillation

摘要： 针对试车中燃气发生器及供应系统自发地产生一阶纵向压力振荡,对系统中各环节建立了满足声学分析的线性化传递矩阵模型,包括液体管路模型、敞口型离心喷嘴动力学模型、流量调节器模型、光滑燃尽曲线的燃烧模型、一维分布参数的燃气流动模型等。求解了发生器相对推进剂流量扰动的幅频响应、液氧和煤油供应系统的喷注导纳。采用Nyquist稳定性判据讨论了发生器和供应系统在不同条件下的耦合稳定性。计算结果与试车现象吻合。在中频范围内,发生器室压对两路推进剂流量脉动都能产生较大的响应,煤油流量扰动引起较大的熵波幅值。由于液氧头腔的容积较大,液氧喷注导纳在宽频范围内都有较高的幅值,且在600～800Hz之间明显大于煤油喷注导纳幅值。发生器-供应系统存在中频不稳定的机理是液氧供应系统出口流量振荡与发生器内声学振荡相耦合。液氧喷注压降和发动机工况的降低对耦合稳定性均产生不利的影响。增加液氧喷注压降可以减小液氧流量振荡的反馈,提高系统的中频耦合稳定性。 

关键词: 富氧燃气发生器;供应系统;幅频响应;耦合稳定性;声学振荡 