Executive Summary : | Shock Wave Boundary Layer Interactions (SWBLI) are inevitable in the case of supersonic and hypersonic flying vehicles. These interaction results in adverse pressure gradients leading to boundary layer flow separation resulting in the generation of a separation bubble, separation shock and reattachment shock making the flowfield complex and highly unsteady. The interaction region is also subjected to severe unsteady pressure and heat loads which not paid proper attention can lead to damage of the vehicle structure, especially in the case of hypersonic Mach numbers. A complete understanding of the SWBLI region is of interest not only from fluid dynamic aspects but also in the design of control mechanism to mitigate its effects. SWBLI are studied on canonical configuration like Impinging Shock on flat plate boundary layer, Forward Facing Step (FFS) and Backward Facing Step (BFS). While a bulk of research has been carried out for supersonic flows studying the unsteady flowfield, for hypersonic flows the flowfield is yet to be fully understood. Especially, for the case of BFS the SWBLI flowfield and the associated unsteadiness is not studied in detail. What role does the incoming Reynold number and step height play on the flow unsteadiness in the separated region, still remains a question. In this regard, the proposed research work aims to study the unsteadiness associated with a BFS in a hypersonic flow. Experiments will be carried out using a Mach 6 hypersonic Ludwieg tunnel test facility at different Reynolds number and varying step height. A 2D flat plate with BFS will be used as test model, instrumented with both pressure and heat flux measurements sensors. The flowfield will be visualized using a high speed Schlieren technique. The effect of Reynolds number and step height on the flow field dynamics; separation bubble size, shear layer oscillation, reattachment shock oscillation etc. are will be studied in the present investigation. |