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热声发动机的起振过程是发生在非均匀声介质中的自激振荡过程,揭示各影响因素之间的耦合关系是热声学基础研究的重要课题.将热声发动机视为由主动网络与被动网络组成的热声振荡器.相应地,推导了组件对应的二端口Y参数,采用负阻模型和反馈模型分别描述了驻波和行波热声发动机,并给出了对应的二端口网络拓扑,应用Nyquist失稳判据获得了热声振荡器的起振条件.模型预测的起振参数,特别是起振频率及模态特征与文献实验报道相符;此外,通过拓扑图论证了驻波热声发动机起振于负阻状态、热声——斯特林发动机存在高频模态.该方法通过考察热声系统的频域响应,实现了以解析方式反映发动机运行参数和系统结构对起振模态、起振温度的影响;能避免使用经验频率设计热声系统,在系统设计阶段提供热稳定性校核的途径。
The thermoacoustic engine start-up process is a spontaneous oscillation process that occurs in non-uniform acoustic media, revealing the coupling between the various influencing factors is an important issue in the basic research of thermoacoustics.As the thermoacoustic engine, Network.Accordingly, the two-port Y parameters corresponding to the components are deduced, and the negative-resistance model and the feedback model are respectively used to describe the standing-wave and traveling-wave thermoacoustic engine and the corresponding two-port network topology , The Nyquist instability criterion is used to obtain the starting conditions of the thermoacoustic oscillator.The onset parameters of the model prediction, especially the starting frequency and mode characteristics, are consistent with those reported in the literature.Furthermore, The acoustic engine starts to vibrate in the negative resistance state, and the thermoacoustic-Stirling engine exists in the high-frequency mode. By investigating the frequency domain response of the thermoacoustic system, the method can reflect the engine operating parameters analytically and the influence of the system structure on the starting mode , Start-up temperature; can avoid the use of empirical frequency thermoacoustic system design, thermal stability in the system design phase to check the way.