高超声速进气道再起动非定常流动机理及参数影响规律研究

The hypersonic inlet self-starting capability is indispensably demanded to guarantee its running state. The self-starting characteristic is affected by various factors, attributing to complex flow during the inlet restart process, such as the movement and evolution of shock wave interferences and boundary layer separations. The classical Kantrowitz criterion for conventional supersonic inlet self-starting therefore becomes invalid because the assumed normal shock doesn't occur at the beginning of the internal contraction. The starting phenomena are not fully understood for hypersonic inlets as yet. Aiming to the aerodynamic problem, this project plans to deeply investigate the unsteady flow pattern during the hypersonic inlet restart process by experiments and numerical simulation,and then abstract the dominant flow structure and key influence factors related to the hypersonic inlet restart characteristics. The parameter effects and the flow mechanism that dominate the inlet self-starting capability will be then studied respectively. The formation mechanism of a critical restart flow will be further elucided. Additionally, the model will be established to reveal the hypersonic inlet self-starting characteristics. A design principle related to hypersonic inlet self-starting would be developed to support the geometry construction of the hypersonic inlet.

自起动能力是高超声速进气道的基本设计要求，由于高超声速进气道再起动过程包含了激波相干、边界层分离等复杂流动结构的非定常运动及演化，针对常规超声速进气道的经典Kantrowitz起动判据所假定的正激波吞入过程不能成立，至今高超声速进气道再起动特性及其关键机制仍未能深入理解。针对这一基础气动问题，本项目开展高超声速进气道再起动过程非定常流动形态的试验及数值研究，提炼影响再起动特性的关键流动特征及几何、气动影响要素，孤立因素探索再起动流动形态及起动特性的参数影响规律，并揭示决定进气道再起动的关键流动机理及再起动临界流态的形成机制。同时，建立反映高超声速进气道自起动特性的多参量模型，发展满足自起动性能要求的设计原则，为高超声速进气道设计提供理论支持。

高超声速进气道再起动性能是超燃冲压发动机工作特性的重要指标之一。由于高超声速进气道再起动过程包含了激波相干、边界层分离等复杂流动结构的非定常运动及演化，针对常规超声速进气道的经典 Kantrowitz 起动判据所假定的正激波吞入过程不能成立，至今高超声速进气道再起动特性及其关键机制仍未能深入理解。.本项目通过风洞实验及数值模拟，分析了高超声速进气道再起动过程非定常流动过程，并定义了进气道再起动过程的三种流态：起动流态，溢流不起动流态以及临界流态。着眼进气道内收缩段激波边界层干扰相关要素，揭示了进气道内波系结构、唇口截面气动参数、壁面温度以及压缩方式是进气道再起动性能的关键影响要素。解耦获得了不同影响参数对进气道再起动性能的影响规律，并揭示了再起动过程的流动机理，为高超声速进气道的工程设计提供理论依据。.研究发现，唇罩激波强度是进气道再起动的主导因素，二元高超声速进气道再起动极限收缩比随激波强度的增加而减小，且性能曲线存在突降现象。而对于弱唇罩激波工况，唇口截面边界层相对厚度达到一定程度后会导致进气道再起动性能的突降现象。类似的，对于弱唇罩激波工况，壁温总温比的减小会诱导进气道再起动性能发生突变，且随着唇罩角度或边界层厚度的减小，进气道再起动性能突变向高无量纲壁面温度的方向移动。数值研究表明，进气道通过的最大流量由几何喉道约束向气动喉道约束的转变是再起动极限收缩比突降的流动本质，且突变区域往往伴随大范围的临界流态的出现。而唇口截面马赫数的增加除有效提升进气道的再起动性能外，还使激波强度-再起动性能曲线的突降向大角度方向移动。.基于影响规律研究，提出了唇罩分级压缩及内收缩段侧压改善进气道再起动能力的设计原则，并进行了验证实验。