钝前缘V字形溢流口激波干扰及气动热特性研究

V-shaped cowl lips with blunt leading edges are commonly used in hypersonic inlets, especially in the inward-turning inlets. The manifold and multiple shock interaction phenomenon on the V-shaped cowl lip embody the prominent features of strong three-dimensional interaction, the coupling between upstream and downstream flow, and unsteady characteristics, which cause a severe aerodynamic environment of extremely high pressure, heating, and fluctuating load. These new features challenge the current theories of shock reflection/interaction and the knowledge of aerothermal environment. And thus, the shock interaction phenomenon on the V-shaped cowl lip cannot be accurately depicted or predicted using these current theories or empirical models. This project plans to thoroughly reveal the complex flow mechanism related to shock reflection/interaction and aerothermal characteristics on the V-shaped cowl lip, by making full use of the existing shock tunnel test bed, designing a series of particular tests, conducting numerical simulations, and carrying out theoretical analyses. The effects of incoming flow conditions and geometric parameters on the transition and hysteresis loop of shock reflection/interaction patterns, the peak of heat flux, and the unsteady flow characteristics will be addressed carefully. And the underlying physical mechanism will be revealed. A criterion for the transition of shock reflection/interaction patterns and reliable prediction methods for the aerothermal characteristics and unsteady flow features are expected to be established. Several new design methods and flow control strategies for the V-shaped cowl-lip will be explored and examined carefully to suppress the severe aerodynamic environment including high-pressure, high-heating, and high-fluctuating. The achievements of this project will lay a foundation for the improvement of aerodynamic design of the V-shaped cowl lips of the hypersonic inward-turning inlets.

以高超声速三维内转式进气道为代表的钝前缘V字形溢流口处多种形式的多次激波干扰现象，具有强三维性、上下游流动的强耦合特性以及非定常特性，导致其气动力/热、脉动环境严酷，使得现有的激波反射与激波干扰理论和气动热环境认知面临新的挑战，难以直接沿用现有的理论和经验模型或判据对其特性进行准确描述和预测。本项目拟充分利用课题组已有的激波风洞实验平台，设计一系列的流动机理实验，并借助数值模拟和理论分析手段，对钝前缘V字形溢流口所涉及到的激波反射与激波干扰以及气动热问题进行细致研究，旨在阐明来流和几何参数对其激波反射与激波干扰类型转变以及迟滞、壁面热流峰值、流场非定常特性的影响规律和作用机理，建立其激波反射与干扰类型的转变准则、气动热特性和非定常流动特性的预测方法，力求探索和发展改善其严酷气动力/热、脉动环境的设计方法和流动控制策略，为高超声速内转式进气道溢流口的气动设计提供理论和方法基础。

针对高超声速三维内转式进气道唇口面临的极高气动热载荷问题，为突出重点并分解难点，提出了一种钝前缘V字形溢流口模型，进而高效揭示了激波干扰导致局部气动热载荷剧增的机理，颠覆了通过增大前缘钝化半径降低气动热载荷的传统观点。通过深入研究，发现钝前缘V字形溢流口流场结构主要呈现异侧激波规则反射、马赫反射和同侧激波规则反射三种类型，揭示了来流马赫数、几何参数等关键因素对激波干扰类型转变以及迟滞的影响规律，创建了钝前缘V字形溢流口激波反射与干扰类型的转变准则和理论分析方法，准确预测了激波干扰类型的转变边界，获得了激波干扰类型的图谱；明晰了壁面气动热载荷的主要产生机制：超声速气流冲击壁面、激波或膨胀波与边界层干扰、剪切层贴附壁面、异侧超声速射流对撞；揭示了激波干扰类型对壁面气动热严酷程度的影响规律，构建了壁面热流峰值与压力峰值之间的关联途径；阐明了射流对撞、旋涡运动等主导激波自持振荡的机理，揭示了激波振荡模式的演变规律，提出了合理预测激波振荡频率的方法或关系式；阐明了三维空间中激波干扰类型转变主导溢流口下游流向涡对生成及演化的机理。在此基础上，提出了“圆锥曲线形中心线”、“非一致钝化前缘”、“椭圆截面钝化前缘”优化构型设计方法以及“自循环抽吸”流动控制措施，不仅能够大幅降低壁面气动力/热载荷，而且能够有效抑制激波振荡并提升流场品质。相关研究在国内外重要期刊上发表论文29篇（含在线发表3篇，已录用1篇），会议论文18篇，获得专利授权2项，培养毕业6名博士研究生。本项目的研究成果，为高超声速内转式进气道唇口气动热防护设计，提供了坚实的理论和方法支撑，并得到了航空航天工业单位的高度重视与支持。