预设堵块法检测进气道自起动能力的数值研究

A Numerical Investigation of Pre-Setting-Blockage Method to Detect Self-Starting Ability of an Inlet

关键词:  高超声速进气道  自起动  数值模拟  动网格  激波风洞

Key words:  Hypersonic inlet  Self-starting  Numerical simulation  Dynamic mesh  Shock tunnel

摘要:

在进气道内预先设置轻质堵块迫使进气道不起动，堵块被气流吹出后流道恢复畅通，为激波风洞提供了一种检测进气道自起动能力的方法。为了深入认识预设堵块方法的检测过程，将堵块简化为一个自由度的刚体运动，采用k-ω SST湍流模型，结合铺层动网格技术，对该检测方法进行了二维非定常数值模拟。在Ma∞ = 5.9条件下，采用改变堵块质量的方式，获得了三种典型的检测过程。通过分析堵块在气动力作用下的运动与进气道非定常波系演化相互耦合的过程，揭示了堵塞作用产生和消除的流动机理。结果表明，堵塞时间没有显著地改变进气道的自起动能力，预设堵块方法成功检测到进气道在Ma∞= 4.9自起动。此外，建立了预估堵块运动的匀加速模型，预估的堵塞时间与数值模拟结果较为符合。在Ma∞ = 5.9条件下，堵块的临界质量约为3.8g。考虑到激波风洞实验时间短暂，应选择合适的堵块。

Abstract:

A testing method to detect an inlet self-starting ability in shock tunnels by pre-setting a blockage in the inlet is presented. The blockage can force the inlet to unstart at the initial testing phase，and then be blown out to open the flow path for the inlet re-starting. To thoroughly study the testing process，the motion of the blockage was simplified as a rigid body with one degree of freedom，and then two-dimensional numerical simulations were performed by applying dynamic mesh technique of layering. The k-ω SST turbulence model was used for the complex flow. Three typical types of flow in the testing process were obtained by varying the mass of the blockage at Ma∞=5.9. The aerodynamics of the blockage combine with the involved unsteady flow features in the inlet was discussed to better understand the physical mechanism of the testing process. The results indicate that the blockage duration does not affect the inlet self-starting ability. The pre-setting-blockage method successfully detect the inlet self-starting process at Ma∞=4.9. Moreover，a uniformly accelerating model was proposed to pre-estimate the motion of the blockage，and the results agree reasonably well with the simulations. The critical mass of the blockage is approximately of 3.8g at Ma∞=5.9. In consideration of the limited test time of shock tunnels，a suitable blockage is recommended to detect the self-starting ability of an inlet.