Aerodynamic Design Of Inlet Layouts Of A Hypersonic Conical Vehicle And Inward Turning Inlets

Condsidering the integration of aircraft/scramjet,the design of hypersonic inlet is essentially accomplished under a series of constraints.The constraints usually include the geometry as well as the aerodynamic performance.In view of this demand,the design method of inward turning inlets was proposed under strong constraints.Meanwhile,the performance of inlet was optimized.The inward turning inlet was designed in integration of conical vehicle.And very different inlet layouts were accomplished.The aerodynamic performance of different inlet layouts were analyzed and compared.The effects of inlet layout on the aerodynamics characteristics of aircrafts were obtained by using computations.Firstly,the work focus on streamline tracing techniques for designing hypersonic inlets,and two deficiencies were discovered.The explanation was given from the flow mechanism and the relationship between the stream-traced inlets and the basic flowfield was clafied.It reveals that constriction ratios of stream-traced inlets are unpredictable and uncontrollable,and stream-traced inlets cannot exactly inherit properties from a basic flowfield through which they are traced.It was made clearly that properties of flow tubes captured by an inlet are what essentially determines constriction ratios as well as performances of inlets.Secondly,the design method of inward turning inlets with controllable constriction ratios was proposed to meet the integration demand and make up for deficiencies of streamline tracing techniques.By combining the parameterization method,the streamline tracing technique,and optimization,it is able to add constraints during the design process and optimize the inlet at the same time.Thirdly,three inlet layouts,including the NIL,OIL and BBIL,were obtained in integration with a conical vehicle.Three inlet layouts have almost the same mass capture performance at the design point.In addition,their self-starting performances were also roughly the same.The performances of different layouts were analyzed under different incoming conditions: the mass capture performance of three inlets all increase with the rise of Mach number and the attack angle.However the OIL inlet has the relative low sensitivity.By analyzing the starting performance,it is able to improve its self-starting performance by utilizing a 2-D leading edge shape.Forthly,four inlet layouts,including the BOIL,BIIL,BOCIL,and BICIL,were obtained with a conical vehicle.The attack angle characteristics of four inlets were mainly analyzed.It reveals that the mass capture of the BOIL and BIIL inlets decrease slowly with the increasing of attack angles.And the mass capture of the BOCIL and BICIL inlets increase fast with the increasing of attack angles.It may be attributed to two factors.One is how the maximum capture area of inlet varies with the attack angle.The other one is the spilliage under off-design conditions.Finally,the aerodynamic characteristics of aircrafts with different inlet layouts were analyzed and compared.The results show that the NIL and BBIL aircraft are statically unstable,and the static instability margin of the NIL aircraft is large,while the static stability of the OIL aircraft is very small.It may be attributed to local normal force generated by different types of inlets.Comparing the aerodynamic characteristics of BOIL,BIIL,BOCIL and BICIL aircrafts,the maximum lift-drag ratios of the BOCIL and BICIL are larger than the non-waveraider layout aircraft(BOIL and BIIL).Moreover,the four aircrafts are static stable,and the inlet fairing is considered to be the main cause of the large static stability margin of the aircraft.