Shock-wave boundary layer interactions(SBLI) occur when the shock wave created by the ramp geometry interacts with the boundary layer. Shock will propagate through a multi-layer viscous and inviscid flow structure. If the boundary layer flow is not laminar, the production of turbulence is enhanced. The adverse pressure gradient across the shock is the major factor in the separation of the boundary layer. Shock induced separation causes the unsteadiness in the flow field and is a key field of research due to the rich flow physics exhibited.
The present work involves two-dimensional experimental and numerical investigation of the SBLI phenomena on a smooth-cornered compression ramp. Enclosed figure shows the geometry of the smooth-cornered compression ramp. The main focus of the present work is to study the size of the separation bubble and the location of flow separation and reattachment downstream of the shock. The study is carried out for three different Mach numbers of 2.25, 3 and 3.5. The analysis is also done for ramp angles of 16° and 20°. The flow visualization is done using the Schileren technique. Pressure measurement is done by pressure transducer, whereas flow velocity is measured by the Laser Doppler Velocimetry (LDV). The numerical analysis is carried out using the OpenFOAM software.
The present study discusses the location and size of the separation bubble obtained from experimental and computational analysis of the different cases. It is observed that, for a given ramp angle, the size of the separation bubble decreases with the increasing Mach number. The bubble size grows as the ramp angle increases for a specific Mach number. The separation and reattachment shock interact to form a lambda shock structure, which is captured in the Schileren images. The effect of Mach number and ramp angle variation on the lambda shock is also discussed.
References:
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5. Holder Babinsky, John K. Harvey, "Shock Wave-Boundary-Layer Interactions," Cambridge University Press, 2011.
