scholarly journals Separated shear layer effect on shock-wave/turbulent-boundary-layer interaction unsteadiness

2018 ◽  
Vol 848 ◽  
pp. 154-192 ◽  
Author(s):  
David Estruch-Samper ◽  
Gaurav Chandola
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Turbulent Boundary Layer ◽  
Shear Layer ◽  
Low Frequency ◽  
Separated Flow ◽  
Layer Interaction ◽  
Separation Shock ◽  
Separated Shear Layer ◽  
Boundary Layer Interaction

This paper presents an experimental study on shock-wave/turbulent-boundary-layer interaction unsteadiness and delves specifically into the shear layer’s role. A range of axisymmetric step-induced interactions is investigated and the scale of separation is altered by over an order of magnitude – mass in the recirculation by two orders – while subjected to constant separation-shock strength. The effect of the separated shear layer on interaction unsteadiness is thus isolated and its kinematics are characterised. Results point at a mechanism whereby the depletion of separated flow is dictated by the state of the large eddy structures at their departure from the bubble. Low-frequency pulsations are found to adjust in response and sustain a reconciling view of an entrainment–recharge process, with both an inherent effect of the upstream boundary layer on shear layer inception and an increase in the mass locally acquired by eddies as they develop downstream.

Experimental Study of Shock Wave / Turbulent Boundary Layer Interaction

2010 ◽  
Vol 3 (2) ◽  
Author(s):  
Pavel Polivanov ◽  
Sidorenko Andrey ◽  
Maslov Anatoliy
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Experimental Study ◽  
Turbulent Boundary Layer ◽  
Separated Flow ◽  
Reflected Shock Wave ◽  
Oblique Shock Wave ◽  
Layer Interaction ◽  
Reflected Shock ◽  
Boundary Layer Interaction

Experimental study of separated flow in a zone of oblique shock wave / turbulent boundary layer interaction was carried out for Mach number 2 and Reynolds number Reθ = 2,7÷3,5 × 103. Streamwise pressure distribution on the model surface was obtained, Schlieren and oil-flow visualizations were performed. The paper gives detailed data of hot-wire anemometry measurements in upstream boundary layer, interaction and recovery regions. Unsteady nature of separated zone and reflected shock wave was discovered. The effect of side walls on quasi 2D structure of separated flow is described.

Low-frequency unsteadiness in shock wave–turbulent boundary layer interaction

2012 ◽  
Vol 699 ◽  
pp. 1-49 ◽  
Author(s):  
Stephan Priebe ◽  
M. Pino Martín
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Turbulent Boundary Layer ◽  
Low Frequency ◽  
Separated Flow ◽  
Frequency Mode ◽  
Statistical Relation ◽  
Boundary Layer Interaction ◽  
Shock Motion ◽  
Low Frequency Mode

AbstractThe low-frequency unsteadiness is characterized in the direct numerical simulation of a shock wave–turbulent boundary layer interaction generated by a $2{4}^{\ensuremath{\circ} } $ compression ramp in Mach 2.9 flow. Consistent with experimental observations, the shock wave in the simulation undergoes a broadband streamwise oscillation at frequencies approximately two orders of magnitude lower than the characteristic frequency of the energetic turbulent scales in the incoming boundary layer. The statistical relation between the low-frequency shock motion and the upstream and downstream flow is investigated. The shock motion is found to be related to a breathing of the separation bubble and an associated flapping of the separated shear layer. A much weaker statistical relation is found with the incoming boundary layer. In order to further characterize the low-frequency mode in the downstream separated flow, the temporal evolution of the low-pass filtered flow field is investigated. The nature of the velocity and vorticity profiles in the initial part of the interaction is found to change considerably depending on the phase of the low-frequency motion. It is conjectured that these changes are due to an inherent instability in the downstream separated flow, and that this instability is the physical origin of the low-frequency unsteadiness. The low-frequency mode observed here is, in certain aspects, reminiscent of an unstable global mode obtained by linear stability analysis of the mean flow in a reflected shock interaction (Touber & Sandham, Theor. Comput. Fluid Dyn., vol. 23, 2009, pp. 79–107).

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