Characterizing the transition between regular and Mach reflections induced by a shock wave–boundary layer interaction

IF 1.7 4区工程技术 Q3 MECHANICS

Shock Waves Pub Date : 2025-01-11 DOI:10.1007/s00193-024-01210-4

S. Scharnowski, R. Baidya, C. J. Kähler

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引用次数: 0

Abstract

Velocity field measurements by means of PIV are used in this work to characterize the flow in a shock wave–boundary layer interaction. For a free-stream Mach number of \(M_\infty =2.56\), the flow over a flat plate model is deflected by a \(16^\circ \) wedge. For these flow conditions, an unsteady dual-state solution is observed where the shock switches between a regular reflection and a Mach reflection. This non-periodic mode switching is atypical for a shock wave–boundary layer interaction and causes significant changes in the flow field. The PIV measurements enable the Mach number and the flow direction to be determined from the measured velocity. In this way, both the position of the shocks and the flow deflection across the shocks can be reliably identified. Our analysis shows that regular reflection rarely occurs and that Mach reflection with varying Mach stem height is present for about \(85\%\) of the measurement time. We provide evidence here that the transition to regular reflection is related to a temporarily thickening of the boundary layer ahead of the shock interaction, which is caused by the breathing of the separation bubble below the shock interaction. This phenomenon results in compression waves that alter the Mach number and flow direction in the region upstream of the shock system, enabling a momentary transition to a regular reflection.

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激波-边界层相互作用诱导的规则反射和马赫反射之间的转换特性

在这项工作中，利用PIV的速度场测量来表征激波-边界层相互作用中的流动。对于自由流马赫数\(M_\infty =2.56\)，平面模型上的流动被\(16^\circ \)楔形物偏转。对于这些流动条件，观察到一个非定常双态解，其中激波在规则反射和马赫反射之间切换。这种非周期模式切换对于激波-边界层相互作用来说是非典型的，并且会引起流场的显著变化。PIV测量可以根据测量的速度确定马赫数和流动方向。通过这种方式，可以可靠地识别激波的位置和流经激波的气流偏转。我们的分析表明，规则反射很少发生，并且在大约\(85\%\)的测量时间内存在随马赫杆高度变化的马赫反射。我们在这里提供的证据表明，向规则反射的转变与激波相互作用之前边界层的暂时增厚有关，这是由激波相互作用下方分离泡的呼吸引起的。这种现象导致压缩波改变了激波系统上游区域的马赫数和流动方向，从而实现了向规则反射的瞬间过渡。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Shock Waves 物理-力学

CiteScore

4.10

自引率

9.10%

发文量

审稿时长

17.4 months

期刊介绍： Shock Waves provides a forum for presenting and discussing new results in all fields where shock and detonation phenomena play a role. The journal addresses physicists, engineers and applied mathematicians working on theoretical, experimental or numerical issues, including diagnostics and flow visualization. The research fields considered include, but are not limited to, aero- and gas dynamics, acoustics, physical chemistry, condensed matter and plasmas, with applications encompassing materials sciences, space sciences, geosciences, life sciences and medicine. Of particular interest are contributions which provide insights into fundamental aspects of the techniques that are relevant to more than one specific research community. The journal publishes scholarly research papers, invited review articles and short notes, as well as comments on papers already published in this journal. Occasionally concise meeting reports of interest to the Shock Waves community are published.