The Investigation On Separation And Control Of Shock Wave/turbulent Boundary Layer Interaction

Flow separation induced by shock wave in the internal flow channel of supersonic and hypersonic aircrafts is one of the key factors affecting engine performance.In the flight process or ground experiment,when the wall temperature or incoming flow parameters are different from the preset,new problems are brought to the shock wave/turbulent boundary layer interaction(SWTBLI),adding great uncertainty to flow field control and design.Based on the background,this thesis takes the supersonic plate SWTBLI problem as the research object.SWTBLI flow field with wall heating/cooling or inflow disturbances are analyzed with large-scale numerical simulation calculations.Furthermore,the separation and control of SWTBLI flow field by transverse jet are investigated.The SWTBLI flow field is simulated and calculated using direct numerical simulation(DNS)method,revealing time-averaged flow field characteristics and coherent structures.Combining the display of the vorticity structure and statistical analysis,the relationship between the near-wall streaks and the development of turbulent kinetic energy in the flow direction is revealed.The analysis of the energy budget terms of the Reynolds stress and turbulent kinetic energy equation further reveals the energy evolution of the SWTBLI flow field and the evolvement of coherent structures.The DNS calculation is adopted to obtain the characteristics of SWTBLI flow field at different wall temperature,revealing the wall temperature effects of SWTBLI flow field.The characteristics of the turbulent boundary layer at different wall temperatures are analyzed comparatively,and the changing laws and mechanisms of its timeaveraged profile,boundary layer thickness,and friction coefficient are compared detailly.The difference in the separation scale of the SWTBLI flow field under different wall temperatures is studied.Furthermore,the flow-direction position of the separation point and the reattachment point are discussed and analyzed.Detailed analysis of the turbulence intensities before and after separation of the boundary layer at different wall temperatures is carried out,displaying the new equilibrium state of turbulent kinetic energy after the wall temperature changes.SWTBLI flow field with artificial inlet periodic disturbances in different frequencies is investigated via large eddy simulation(LES).The time-averaged characteristics and instantaneous structures under effect of different disturbances are studied.The results indicate that the inner and outer layer of turbulent boundary layer show different reactions to the disturbances.The "breathing" effect of the separation bubble is confirmed in the comparative analysis of the separation scale under different disturbances,and the mechanical reason why the reattachment point remains unchanged while the separation point moves upstream is explained.Based on the spectrum analysis,the different rules of the near-wall streaks and the outer large-scale coherent structures of the SWTBLI flow field under effect of the disturbance signal are found,testifying the different responses of the inner and outer layer to the disturbances.Jet wake in the supersonic turbulent boundary layer is studied.The results show the development of counter-rotating vortex pair(CVP).As the size of CVP structure increases,its influence on both sides of the flow field becomes wider.But with the weakening of the turbulence intensity of the central slice of the jet,it means that the momentum exchange enhancement effect of the large-scale vortex structure on the central section is gradually weakened.The turbulence decay phenomenon on both sides of the jet separation area is confirmed.The analysis of the turbulence intensity at different spanwise slices reveals the turbulence intensity change process of the inner and outer layers during the development of the wake.It is found that the structures and turbulent intensity in the inner and outer layers have a visible difference on the recovery speed after the influence of the jet wake.The recovery speed of the inner layer is significantly faster than the outer layer.The transverse jet is introduced to SWTBLI flow field for separation control,and the characteristics of the interference zone under the influence of jet wakes at different distances are compared.Combining the turbulence statistics of different spanwise slices and the difference in the size and shape of the separation bubble,the qualitative mechanism of the movement of the separation point and reattachment point is proposed.The streamwise position of the reattachment point is dominated by the intensity of the incident shock wave and the characteristics of the bottom layer and has little relationship with the intensity of the upper layer turbulence.The position of the separation point is significantly determined by the intensity of the upper layer turbulence.On this basis,the three-dimensional structure characteristics of the separation bubble and its change mechanism under the influence of jet wakes at different distances are further clarified.