Abstract The interaction of a plane shock wave in air with concave profiles has been used in the past mainly to understand the nature of shock wave focusing. The current study examines the complex two-dimensional flow field resulting from the interaction of a plane shock wave entering a symmetrical cavity with curved walls. Of particular interest are the development of reflection patterns of the incident shock wave at the profile wall and the process of gas dynamic focus. These principal flow features are examined across a wide range of different reflector shapes. This includes a review of previously studied profiles such as cylindrical and parabolic, and also of a number of additional profiles, including compound profiles, where an inlet profile merging with that of the main cavity is shown to have major effects on the focusing mechanism and pressures. The various reflector shapes were specified by varying the shape of the profile and the depth-to-aperture ratio. The strength of the incident plane shock wave was limited between Mach numbers of 1.04 and 1.45. The principal flow features were established and examined experimentally using a variety of qualitative and quantitative flow visualization techniques, supplemented with numerical results. Time-resolved high-speed imaging was used to capture the interaction providing the unique ability to track the various transient flow features over the course of the interaction. The three primary factors that influence the maximum pressure amplification at focus, and the focus mechanism, are the incident shock strength, the depth-to-aperture ratio of the profile and an inlet profile leading into the main cavity, if present. An inlet profile results in higher-pressure amplifications for corresponding shock strengths and depth-to-aperture ratios. Increases in the depth-to-aperture ratio increase the maximum pressure amplification observed at focus. This occurs due to a combination of factors including: the strengthening of the individual shock waves involved in focus; the duration of focus; and the strengthening of a compressive flow field that develops adjacent to the shock system during focus. The compressive flow field adjacent to the shock system at focus is shown to be of great importance to the focus process. Graphic abstract

中文翻译：

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凹腔内的冲击波相互作用

摘要 空气中平面激波与凹面轮廓的相互作用过去主要用于理解激波聚焦的性质。当前的研究检查了由于平面冲击波进入具有弯曲壁的对称腔体的相互作用而产生的复杂二维流场。特别令人感兴趣的是在剖面壁处入射冲击波的反射模式的发展和气体动态聚焦的过程。在各种不同的反射器形状上检查这些主要流动特征。这包括对先前研究的轮廓（例如圆柱和抛物线）以及许多其他轮廓（包括复合轮廓）的回顾，其中入口轮廓与主腔的轮廓合并对聚焦机制和压力有重大影响。通过改变轮廓形状和深度孔径比来指定各种反射器形状。入射平面激波的强度被限制在 1.04 和 1.45 马赫数之间。使用各种定性和定量流动可视化技术，辅以数值结果，建立并通过实验检查了主要流动特征。时间分辨高速成像用于捕捉相互作用，提供在相互作用过程中跟踪各种瞬态流动特征的独特能力。影响聚焦处最大压力放大和聚焦机制的三个主要因素是入射冲击强度、轮廓的深度孔径比和通向主腔的入口轮廓（如果存在）。入口剖面导致相应冲击强度和深度孔径比的更高压力放大。深度孔径比的增加会增加在焦点处观察到的最大压力放大。这是由于多种因素的综合作用而发生的，包括：聚焦中涉及的单个冲击波的加强；专注的持续时间；以及在聚焦期间在激波系统附近形成的压缩流场的加强。与聚焦激波系统相邻的压缩流场对聚焦过程非常重要。图形摘要 入口剖面导致相应冲击强度和深度孔径比的更高压力放大。深度孔径比的增加会增加在焦点处观察到的最大压力放大。这是由于多种因素的综合作用而发生的，包括：聚焦中涉及的单个冲击波的加强；专注的持续时间；以及在聚焦期间在激波系统附近形成的压缩流场的加强。与聚焦激波系统相邻的压缩流场对聚焦过程非常重要。图形摘要 入口剖面导致相应冲击强度和深度孔径比的更高压力放大。深度孔径比的增加会增加在焦点处观察到的最大压力放大。这是由于多种因素的综合作用而发生的，包括：聚焦中涉及的单个冲击波的加强；专注的持续时间；以及在聚焦期间在激波系统附近形成的压缩流场的加强。与聚焦激波系统相邻的压缩流场对聚焦过程非常重要。图形摘要 这是由于多种因素的综合作用而发生的，包括：聚焦中涉及的单个冲击波的加强；专注的持续时间；以及在聚焦期间在激波系统附近形成的压缩流场的加强。与聚焦激波系统相邻的压缩流场对聚焦过程非常重要。图形摘要 这是由于多种因素的综合作用而发生的，包括：聚焦中涉及的单个冲击波的加强；专注的持续时间；以及在聚焦期间在激波系统附近形成的压缩流场的加强。与聚焦激波系统相邻的压缩流场对聚焦过程非常重要。图形摘要