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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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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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.