迎角变化引起的高超声速进气道起动迟滞现象试验研究

高超声速进气道在起动过程中存在迟滞现象，起动迟滞对发动机的工作范围有重要影响。以一种Bump/前体一体化进气道为研究对象，通过试验和数值仿真结合的方法，研究迎角变化引起的进气道起动迟滞现象。试验在国防科技大学LF-220自由射流风洞中进行，来流条件Ma=5.0，采用蓄热式加热器对上游气流进行加热，稳定段总压1.59MPa，试验段静温91.67K。试验模型由底座、进气道前体前锥、进气道前体后锥和唇罩4部分组成，模型总长度285mm。采用PSI压力传感器对模型壁面压力进行测量，采样频率为100Hz。试验成功捕捉到进气道随迎角变化由不起动转化为起动的动态过程。研究表明，高超声速进气道随迎角变化存在明显的迟滞现象。试验获得进气道自起动迎角为-1.3°，而进气道自不起动迎角大于10°。在进气道自起动/自不起动过程的研究中发现，随着进气道流动状态的不同，迎角和大尺度分离区交替主导流量变化。

Experimental study on hysteresis phenomenon of hypersonic inlet caused by variations of angle of attack

Hysteresis phenomenon occurs in the process of hypersonic inlet start, which has an important influence on the working range of the scramjet. In this paper, a hypersonic inlet is introduced, and the inlet hysteresis caused by variations of angle of attack is studied by experiment and numerical simulation. The experiment is conducted in a free-jet wind tunnel LF-220 of NUDT (National University of Defense Technology) at Ma=5.0. The regenerative electric heater is used to heat the high-pressure airflow. The total pressure in the settling chamber is 1.59MPa, and the static temperature in the test section is 91.67K. The model is constituted of the first part of forebody, the second part of forebody, the cowl and the lampstand. The pressure sensors are used to measure the wall pressure at a frequency of 100Hz. The dynamic process from unstart to start with the change of angle of attack is captured in the experiment, and the self-starting/-unstarting performances are obtained. The results show that a significant hysteresis occurs in hypersonic inlets with the change of angle of attack. In the experiment, the self-starting angle of attack is -1.3°, while the self-unstarting angle of attack is larger than 10°. In the study of the self-starting/-unstarting process, it is found that the angle of attack and the large-scale separation zone alternately dominate the mass flow.