Shock-Wave Boundary-Layer Interaction Study on a Compression Corner Using Pressure-Sensitive Paint

Control of incident shock-induced boundary-layer separation using steady micro-jet actuators at M∞ = 3.5

“…In order to satisfy the constant U s,max condition with increased entrainment effect brought in by the control device, the separation point location should experience a downstream shift in its location which is in addition to the separation line modification brought about by the momentum exchange induced by the micro-vortices as documented earlier. 18,19–21 The above physical phenomenon was experimentally observed using qualitative and quantitative data for the MJVG1 and MJVG2 cases wherein the thickening of the shear layer is synchronized with the reduction in the intermittent length ( L s ) and increase in central frequency and better cross-correlation values. However, for the other two control cases, the Schlieren images show no major change in thickness of the shear layer when compared with no-control.…”

“…As reported earlier, 23–25 the interaction between the micro-jets and the cross-stream flow creates micro-vortices that are embedded inside the boundary-layer upstream of the interaction, and these micro-vortices give fullness to the boundary-layer profile by taking away the low momentum fluid close to the wall and filling it with the high momentum fluid 18 which modifies the separation line with a corrugated separation line. 19–21 These micro-vortices on crossing the separation point lift off from the surface and are carried along with the shear layer 41 as shown in Figure 21(b). The presence of micro-vortices generated by flow control devices in addition to the vortex component generated by the upstream boundary layer 41 enhances the entrainment effect in the shear layer, which aids in faster mixing, resulting in larger acceleration of the detrimental stream line ( D ) with control.…”

“…The presence of low momentum fluid nearer to the wall and availability of energetic fluid in the free stream across the boundary layer leads to the development of forced mixing devices 14 which helps in redistributing the energy across the boundary layer. The majority of the control techniques [15][16][17][18][19][20][21][22] relies on generation of the vortices closer to the wall, with an aim to balance the energy between the near wall and the free stream of the fluid. In general, there are two approaches available to generate vortices passive or active method, depending on the involvement of external energy.…”

“…In general, there are two approaches available to generate vortices passive or active method, depending on the involvement of external energy. The passive way of flow control generates vortices [15][16][17][18][19][20][21][22] with the help of vanes or ramps placed inside the turbulent boundary layer, and distributed all along the span-wise direction. On the other hand, the active device generates vortices [23][24][25] based on the secondary energy level supplied and its subsequent interaction to the cross-stream flow.…”