Correlation of separation shock motion with pressure fluctuations inthe incoming boundary layer

Experimental study of unsteadiness in supersonic shock-wave/turbulent boundary-layer interactions with separation

“…Later studies suggested that the separated shear layer could result in a low frequency motion of the subsonic bubble which would consequently provoke the oscillation of the separation shock (17) . This hypothesis was also backed in later experimental work that linked the low frequency motion of the reflected shock with the expansion and contraction of the separation bubble (18,19) .…”

Analysis of Material Behavior for Friction in a Nozzle for Turbomachinery and High Speed Vehicles

“…in reality reflects the intermittent, random motion of the shock between xi and x p [3]. As the shock-compression wave system oscillates randomly above (and partially within) the boundary layer, the associated pressure jump across the system is transmitted across the boundary layer on a time scale   tion point essentially tracks the random position of the shock-compression wave system, where the position of the separation point is described by a Gaussian distribution over the length of the interaction zone [3].…”

“…Shock-induced separation of turbulent boundary layers represents a long-studied problem in compressible flow, bearing, for example, on applications in high speed aerodynamics, rocketry, wind tunnel design, and turbo machinery. Experimental investigations have generally sought to expose essential physics using geometrically simple configurations, e.g., supersonic flow over compression ramps [1][2][3][4], curved surfaces [2], backward and forward facing steps [2], simplified wing shapes [5], and various blunt objects [4,6,7]. While a variety of computational and analytical methods have also been developed for treating the problem, the methods are typically applicable to specific compressible flow regimes, i.e., transonic, supersonic or hypersonic flow, and moreover, due to the intrinsic unsteadiness of the separation process, require problem-specific tuning.…”

Experimental results on unsteady shock-wave/boundary-layer interaction induced by an impinging shock

“…Various attempts were made to understand the influence of the incoming boundary layer on the dynamics of the interaction. Erengil and Dolling [6] suggest that high-frequency movements might be caused by turbulent structures convected into the interaction. However Beresh et al [7], who used Particle Image Velocimetry (PIV), suggest that the low-frequency movements of the shock are not driven by the incoming boundary layer.…”

“…With regard to the unsteadiness of the shock-wave/boundary-layer interaction, Dolling concludes that no comprehensive theory exists to explain the phenomena observed in a great number of experiments and suggests that new experiments with non-intrusive highspeed instrumentation such as CCD cameras or laser-based techniques in combination with high-speed pressure transducers accompanied by high-fidelity numerical simulation might lead to a better understanding of the unsteady behaviour of the interaction. Notable experiments in this field were done by Erengil and Dolling [6], Beresh et al [7], Dupont et al [8], Bookey et al [9], Ganapathisubramani et al [10], and Humble et al [11], a comparison of some experiments is provided by Dussauge et al [12]. Numerical results were obtained by Pirozzoli and Grasso [13,Ringuette et al [14], Touber and Sandham [15], Grilli et al [16,17], a comparison of some Large Eddy Simulations (LES) is given by Touber and Sandham [18].…”