Analysis Of High Speed Flow Structure Controlled By Shock Reflection And Separation

In the inlet and isolator of hypersonic vehicle,nozzle and diffuser of hypersonic wind tunnel,complex flow structure caused by interaction between shock wave and boundary layer often appears,which is called shock train.Because of the complexity of parameters in actual flow,the structure of shock train in supersonic pipe usually presents asymmetry and unsteadiness,which has an important influence on the aerodynamic characteristics and fatigue life of the structural components.Therefore,it is of great practical significance to study the flow field mechanism of shock train in supersonic pipe and to explore the control method of the structure of shock train.In this paper,a theoretical model of asymmetric oblique shock train in supersonic pipe with Mach number of 2.7 is established based on the principle of minimum entropy production,and a new formula of equivalent back pressure and entropy production factor is derived.The theoretical results are compared with the results of numerical simulation,wind tunnel test and other literature,and the agreement is good,which verifies the feasibility of the theoretical model.Then,several pipe models with double cavities or double wedges are designed in this paper,and the control effect on the symmetry of start points and shock angles of the leading shocks on the top and bottom wall is studied.It is found that in the double cavities model,the leading-edge point of the cavities can stabilize the start points of the leading shock and make the shock angle of the top and bottom wall equal.In the double wedges models,with the increase of wedge angle and bottom edge size,the leading shock angles of the oblique shock train increases,and the asymmetry of the start points on the top and bottom wall decreases.