Design Method,Numerical Simulation And Experimental Research Of Variable Geometry Inlet With Wide Speed Range

The fixed geometry inlet has better performance only in the design point accessories,which is difficult to meet the requirements of hypersonic propulsion system in wide speed range.Variable geometry inlet has good performance in a wide Mach number range,so its design and research are of great significance.In this paper,a variable geometry inlet with rotating cowl and ramp is studied by means of design,numerical simulation and experiment.Firstly,the wind tunnel test system and numerical simulation method are introduced,and the design essentials and methods of hypersonic inlet are introduced.The startup performance of inlet and the performance of three-dimensional inlet with or without side compression are studied.The results show that the side compression plate can effectively improve the inlet diffusing capacity and the inlet capturing capacity.However,there is a certain total pressure loss to side compression.Equivalent entropy type surface has carried on the design and simulation study.Secondly,a variable geometry inlet with rotating cowl and ramp is designed.The two-dimensional configuration is simulated by rotating ramp,rotating ramp and cowl together.The three-dimensional simulation of rotating ramp is also carried out.The numerical simulation of variable geometry inlet with rotating ramp and cowl is carried out using dynamic meshes.The simulation results show that the design of rotating ramp variable geometry scheme can effectively widen the inlet starter Mach number.The starting Mach number of the reference inlet is reduced from Ma4 to Ma2,and can realize self-starting at Ma2.By rotating the cowl and the ramp,the inlet can be turned from the unstarting state to the starting state.The variable geometry scheme has good flow capture ability and this is beneficial to the acceleration of the aircraft.Thirdly,The effects of the rotating cowl and the ramp on the startability of the inlet are studied through experiments.The results of experiment and simulation are compared and analyzed.Through analysis of the experiment results,it is concluded that:When the inlet does not start,the separation of boundary layer can be gradually reduced by rotating the ramp,and the throat blockage can be reduced too.The ramp rotates to a certain extent to make the inlet self-start again.By rotating the cowl,the contraction ratio in the inlet can be changed.On the one hand,the separation zone of boundary layer can be reduced,the separation position can be moved backward,and the startability of the inlet can be improved.On the other hand,when the inlet is in starting state,the rotating cowl can maximize the inlet flow capture capacity and compress pressure capacity,which is conducive to the acceleration of the aircraft;the interaction between the rotating cowl and the ramp can make the inlet work reliably and adjust to the optimal state at any time.Finally,a new type of inlet design with a partition at the cowl of the inlet is studied.The results of theoretical analysis and simulation show that adding a partition can effectively eliminate the boundary layer separation,reduce the starting Mach number and improve the anti-pressure capability of the inlet.