Effect of freestream noise and boundary-layer transition on hypersonic shock-wave/boundary-layer interaction unsteadiness

IF 1.8 4区工程技术 Q3 MECHANICS Shock Waves Pub Date : 2026-09-26 DOI:10.1007/s00193-026-01286-0

E. Nicotra, S. Bane, J. Jewell

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Abstract

The low-frequency shock and separation unsteadiness resulting from a three-dimensional transitional shock-wave/boundary-layer interaction is investigated for different freestream noise levels and incoming boundary-layer states in a quiet Mach-6 wind tunnel. In low-disturbance flow, the cone-slice-ramp geometry is studied with and without upstream boundary-layer trips, resulting in upstream-transitional and interaction-transitional SWBLI, respectively. When applied, the trips excite the second-mode instability, and the unsteady separation motion is studied for a range of second-mode magnitudes in the transitional upstream boundary layer. The effect of freestream noise is studied by operating the wind tunnel in both its low-disturbance and conventional-noise configurations. Unsteady separation motion is tracked by identifying the shear-layer location in schlieren visualization videos; pressure fluctuations are measured in the incoming boundary layer and inside the separation bubble. Exciting the second-mode instability in the boundary layer in quiet flow initially increases the magnitude of the unsteadiness and alters its frequency content by amplifying oscillations at \(\textrm{Sr}_L=\) 0.025–0.05; however, as second-mode amplitude increases and separation length decreases, this trend reverses and the unsteadiness is suppressed. The comparison of upstream-transitional SWBLI in quiet and noisy flows suggests that the pressure fluctuations in the noisy freestream are interacting with the mechanism responsible for SWBLI and significantly amplifying the unsteadiness over all frequencies.

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自由流噪声和边界层转捩对高超声速激波/边界层相互作用非定常的影响

在安静的6马赫风洞中，研究了不同自由流噪声水平和来流边界层状态下，三维过渡激波/边界层相互作用引起的低频激波和分离非定常。在低扰动流动中，研究了有和没有上游边界层跳闸导致的上游过渡和相互作用过渡SWBLI的锥片斜坡几何形状。在此基础上，研究了上游过渡边界层在一定范围内的非定常分离运动。通过对风洞进行低扰动和常规噪声两种配置，研究了自由流噪声对风洞的影响。通过识别纹影可视化视频中的剪切层位置，跟踪非定常分离运动；测量了进入边界层和分离泡内部的压力波动。在安静流动中，通过放大\(\textrm{Sr}_L=\) 0.025-0.05的振荡，在边界层中激发第二模不稳定性，使非稳定性的量级增加，并改变了其频率含量；然而，随着第二模振幅的增大和分离长度的减小，这种趋势发生逆转，非稳定性被抑制。通过对静流和含噪流上游过渡期SWBLI的比较，发现含噪流的压力波动与SWBLI的产生机制相互作用，显著放大了各频率的非定常性。

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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.