Executive Summary : | Over the last couple of decades, the research related to shock-wave or boundary-layer interaction (sWBLI) has attracted more attention due to its applications in air intakes, supersonic nozzles, and launch vehicles. A thin boundary layer (BL) starts to grow from the leading edge of a vehicle when fluid flows over a solid surface. In supersonic or hypersonic vehicles, the shock wave compresses the incoming flow, reduces velocity, and increases the internal energy of the flow. The shock wave also produces an adverse pressure gradient by increasing the local pressure on the flow field, which subsequently thickens the BL. It causes BL separation in the extreme cases, which drastically alters the flow field. This BL separation is not desirable, causes structural damage, and finally downgrades the efficiency of the aircraft. In supersonic air intakes, sWBLI reduces their efficiency due to the formation of a small separation bubble and strong unsteady separation. The separation zone enlarges due to the growth of the separation bubble and partially blocks the flow path, which causes an unstart of an intake. A number of literatures are available that have discussed the flow physics related to the interaction of different types of boundary layers with different intensities of shock waves and related flow separation with its control mechanism both experimentally and numerically. Recently, many researchers have discussed the unsteady effects of shock-induced separation due to its application in supersonic or hypersonic flows. However, the determination of the separation length of the sWBLI over a wide range of supersonic and hypersonic Mach numbers considering the unsteadiness of the sWBLI is never attempted, though a few groups have studied the flow field at selected Mach numbers. In this project, a shock wave with different strengths will be generated by placing a wedge in the supersonic inflow, and it will impinge on a boundary layer to examine the characteristics of bubbles and the associated separation. The nature of the boundary layer will be varied by increasing the length of the flat plate from the location of shock wave impingement. A numerical analysis will be performed at different shock strengths to characterize the unsteady effect of sWBLI. Experiments will be performed in shock tubes, and the shock cell structures will be captured using schlieren imaging to validate the numerical results. A three-dimensional in-house numerical solver will be developed for detailed analysis of sWBLI over a wide range of Mach numbers (1 ≤ M ≤ 5). The dependency of different flow parameters on the separation length will be examined in detail, and correlations will be proposed to determine the separation length at supersonic and hypersonic regimes, which can predict the size of the separation bubble in the sWBLI by considering the unsteadiness. |