Integrated Aerodynamic Design And Experimental Study On Forebody And Inlet Of A Hypersonic Vehicle

The hypersonic vehicles,which have a wide range of application prospect and potential economic value,is one of the important technologies of future aircraft.The current thesis mainly focuses on the integrated design of hypersonic vehicle forebody and inlet as well as the wind tunnel test research.Firstly,a combined flow named IBB flow,which consists of ICFA flow(Internal Conical Flow A),external compression truncated Busemann flow,and internal compression truncated Busemann flow,is proposed in this thesis,based on which,an integrated configuration of RBCC vehicle forebody and parallel modular inlet of strut engine has been designed.The designed model is studied computationally and experimentally,and the results show that the IBB inlet at the design point of Ma 6 could be started in the Mach number range of 3 to 6.5 with high performance in total pressure recovery and flow coefficient.Secondly,a research of inlet unstart of single module and a research of flow interaction between adjacent inlets of parallel modules are carried out based on the designed test model.The high speed Schlieren and the fast response pressure transducers are employed to study the relation between separation shock oscillation and wall pressure fluctuation around the cowl area when the inlet is in the state of unstart.The double peaks in the pressure fluctuation cycles is studied in details,and it is confirmed that the motion of separation shock plays an important role in this phenomenon.The evolution of flow interaction between parallel modules is studied,and the accompanying process of disturbance propagation includes four typical stages,known as “double start”,“single start”,“transitional stage” and “double unstart”.Furthermore,the downstream flow disturbance is usually characterized by massive separation region,while the upstream flow disturbance works in the mode of local separaion with downstream rettachment.However,both of the two modes could lead to inlet unstart by reducing flow coefficient.Therefore,the unstart inlet of one module could lead to the unstart of adjacent modules,which should be avoided before transitional stage.Lastly,the relation between separation induced shock configuration and downstream pressure disturbance around cowl area of inlet is researched,and a theoretical analysis model is established.In this theoretical method,equivalent pressure and entropy factor are proposed,and the minimum entropy production principle is employed to connect the shock configuration with upstream as well as downstream flow condition.It is found that,there will be several different configurations with the increasing downstream pressure disturbance,including symmetrical regular reflection,asymmetrical regular reflection,and symmetrical Mach reflection.On the other hand,there is a solution path residing in the overall RR domain and the strong incident shock polar line,along which the reflected shock solutions fulfill the minimum entropy production.Furthermore,the shock configuration is relatively steady before the path reaches strong incident shock polar line,while it is unsteady after that.Therefore,the solution path is very helpful to determine incident shock angles that may induce the steadiest shock configurations in separation-induced flows.