【作者】 黄玉辉；

【导师】 王振国；

【作者基本信息】 国防科学技术大学 ， 航空宇航推进理论与工程， 2001， 博士

【摘要】 本文结合非平衡热力学、小波分析、非线性动力学等非线性学科,建立燃烧稳定性理论模型,发展两相喷雾燃烧非定常数值模拟程序,利用激光测粒系统,发动机高频热试系统等测试手段,重点围绕液体推进剂的化学动力学过程,对燃烧不稳定进行了较为系统的理论、仿真和实验研究。 ●建立非线性场振子模型,比较燃烧速度对压力导数前三项系数的作用。 ●提出均匀反应器声振模型。发现燃烧区的传热是燃烧过程的Hopf分岔参数:化学动力学过程也具有频率选择、频率牵引和非线性激发的特点。 ●建立时空作用模型。提出不同声振模式之间的竞争与合作概念。发现若非线性互饱和系数较小,各振型共同分享振动能量;否则,只能有一个主振型振荡。 ●用非平衡热力学分析燃烧不稳定。结果表明由扩散控制的蒸发过程不可能包含振荡激励机理。得到燃烧稳定性一般热力学判据。 ●数值研究燃烧室的一维非线性声学。发现压力和速度主要体现声特征,熵和组分主要体现流特征,而密度和温度既体现声特征又体现流特征。 ●用EBU模型三维数值研究气相湍流火焰。EBU模型不包含燃烧振荡机理。结果表明用包含着火和灭火过程的EBU模型可以产生燃烧振荡,但不会持续太久。 ●用简化多步化学反应动力学数值研究气相火焰。发现高活化能的预混火焰比扩散火焰容易产生振荡,但振荡难以持久。 ●用简化多步化学反应动力学数值研究液氧/煤油,气氧/煤油/气氢,和液氧/气氢喷雾火焰。自激燃烧振荡形成极限环。增加气氢占燃料的质量比,增加气氧的喷射速度都有助于提高燃烧稳定性。提出判定燃烧不稳定敏感区的方法。喷嘴附近温度适中的预混区为燃烧振荡提供了能量。 ●实验发现并研究YF-75发动机同轴离心式喷嘴的自激振荡。这是中心气涡与气体通道中的气流共振的结果。对喷雾的滴径分布和喷嘴下游的流强分布产生重要影响。 ●用充填,气动噪声,脉冲枪和扩音器实验研究燃烧室的各种声学响应。实验研究液氧/气氢/煤油三组元两工况发动机在不同结构和工作条件下的燃烧稳定性。发现氢气的加入对烃/氧燃烧稳定性的提高不是绝对的。 ●提出判定燃烧不稳定激励机理的实验方法,并提出第三种燃烧不稳定控制方法。更多还原

【Abstract】 Combustion instability in liquid rocket engine is investigated with theoretical analyses, numerical simulations and experiments. Nonlinear science, such as Nonlinear Dynamics, Non- equilibrium Thermodynamics, and Wavelets, is introduced in the studies.Nonlinear oscillation equation of chamber pressure is established. The first three coefficients of combustion Vs pressure play different roles in combustion instability.Continuous Stirred Tank Reactor Acoustic Model is put forward. The heat transfer is the important Hopf bifurcation parameter. The self-catalyze mechanism may drive the combustion oscillate at an inherent frequency, and can provide frequency-draught and nonlinear inspiration behaviors.Temporal-spatial interaction model is established. The concept of competition and cooperation of the acoustic modes is introduced. Different acoustic modes can shares oscillation energy if the nonlinear interaction coefficient is little. Otherwise, only one mode gets instability.Non-equilibrium Thermodynamics is used to analyze the combustion instability. The vaporization models controlled by diffusion process can not include driving mechanism. General thermodynamics stability criterion of combustion is got.The nonlinear acoustic process is numerically simulated. It is found that the pressure and velocity disturbances run at sound speed, the entropy and components at flow speed, the temperature and density partly at sound speed, partly at flow speed.Gas combustion instability is numerically simulated with EBU model. The standard EBU model can not drive combustion to oscillate. The amendatory EBU model including ignition and extinguish mechanism can drive the combustion to oscillate. However, the oscillation can not last for a long time.Combustion instability of gas and spray flame in a lab-scale O₂/Kersene/H₂ tripropellant rocket engine is numerically studied. The diffusion and premixed gas flame are always stable in our simulations, though the premixed gas flame will oscillate for a period of time when the activation energy is artificially enlarged.The spray flames can self-oscillate from startup sequence with large amplitudes, and eventually reach limited cycles. The LO₂/Kerosene biproprellant spray flame is the most unstable case, and its stability is improved when gas hydrogen is injected and the velocity of gas oxygen is increased. Correlation of the numerical results on the basis of flow visualization and theoretical analyses indicate chemical kinetic play an important role in the combustion instability.During the experiments on the coaxial swirl injector of YF-75 engine, the injector can self-oscillate. This behavior is the result of the coupling between the gas vortex and the gas channel. It can affect the droplet distribution.Different inspiring methods are used to experimentally study the acoustic characteristics of the small chamber.Combustion instability of tripropellant rocket engine under different condition is experimentally studied. It is not absolute to improve the hydrogen/oxygen combustion stability by adding hydrogen.The experiment method to determinant the driving mechanism is put forward. The third control method of combustion instability besides the passive control and the active control is also brought forward.The research of the author shows that the chemistry dynamics can explain well almost all the combustion instability phenomenon, and the chemistry dynamics may be the driving mechanism of combustion instability in liquid rocket engine.更多还原