Investigation On The Three-dimensional Swept Impinging Oblique Shock/Turbulent Boundary Layer Interactions

Shock wave/boundary layer interactions are the inevitable phenomenon in the flowfields of hypersonic inlets.The separated boundary layer induced by the shock waves will reduce the quality of the flows in the inlets,and will cause the unstart of the inlets when the inflow Mach number is low or the backpressure is high.Compared with the two-dimensional shock/wave boundary layer interactions,the three-dimensional interactions have more complicated flow mechanisms,and have significant effects on the performance of hypersonic inlets.In this thesis,the swept impinging oblique shock wave/turbulent boundary layer interactions(SIOS/TBLI)were studied theoretically,numerically and experimently.Three-dimensional reflection of the swept impinging oblique shock(SIOS)in the inviscid flow is theoretically studied.A simplified flow model is proposed for the three-dimensional reflection flowfield of SIOS;a general theoretical method is proposed for the reflection of the three-dimensional planar shock waves,and this method is applied to solve the three-dimensional reflection flowfield of SIOS;The influence of the parameters of SIOS on the reflection flowfield is investigated,as a result,the transition process of SIOS into its specific form(Swept Shock,SS)is uncovered.The mechanism of the mean structure of SIOS/TBLI is investigated and the simplified flow model is established.Based on the proposed theoretical method,typical parameters of SIOS are chosed and SIOS/TBLI are experimentally studied.The mean flowfield structure of separated flowfield is studied,and the results show that: the separated boundary layer is quasi-conical and the wave configuration of shock structures is regular reflection type or Mach reflection type.The interaction of the inviscid reflection flowfield and the viscous interaction flowfield are analyzed.The results show that,the increase of the flow deflection angle and the swept angle will both lead the shock reflection type converts from regular reflection into Mach reflection.On the basis of these study,the simplified flow model of the mean structure of SIOS/TBLI is established and the flow mechanism is summarized.The influence of the Reynolds number and the inviscid reflection flowfield on the separated flow of SIOS/TBLI is investigated.The strength and sweep effects of the inviscid reflection flowfield are divided.The character of the plateau pressure on the wall are investigated and the prediction method is proposed.Furthermore,this prediction method can be also applied to the swept shock wave/turbulent boundary layer interaction(SS/TBLI).The effects of the Reynolds number,the shock strength and sweep on the mean characteristics of the separation flowfield are also studied.The results show that,as the increase of the Reynolds number,the scale of the separation region become larger,however,the location of the separation region and the mass flow rate of the boundary layer remain unchanged;as the strength of SIOS increase,the scale of the separation region and its boundary layer mass flow rate beome larger,and the location of the separation region moves upstream;as the sweep angle of SIOS increase,the scale and mass flow reate of the separation region become larger,however,the location of the separation region remain unchanged.The special form of SIOS/TBLI,viz.SS/TBLI is studied.The mean structure of SS/TBLI is visualized and the simplified model of the “?” shock is established.Furthermore,two quantitative relationships are found: the pressure downstream of the separation shock is equal to the plateau pressure on the wall;the interaction line of the separation shock and the wall is parallel to the upstream influence line.Based on these two relationships,a theoretical method is proposed to analyze the “?” shock.In order to uncover the mechanism of pressure balance in SS/TBLI,the separated boundary layer and the “?” shock are regared as a system which is in pressure balance,and then,under the effect of another swept shock,the process in which this system converts from the current state into another state is analyzed.Moreover,the influence of the compression angle on the mean characteristics of SS/TBLI is studied.The results show that,as the increase of the compression angle,the scale and the mass flow rate of the separation region become larger,and the separation region moves upstream.