The Improvement Research On The Aerodynamic Design Of Hypersonic Vehicle/Propulsion Integration

Hypersonic technology has become a key research direction in aerospace.Compared with traditional aircraft,hypersonic flight is more in line with the military and civilian pursuit of speed and economy,which will revolutionize the future development of aerospace industry.Airframe/propulsion integration is the core technology of hypersonic vehicle.The hypersonic vehicle and external parallel TBCC engine propulsion system are designed for the hypothetical requirement of achieving global arrival within 1.5h.CFD numerical analysis was conducted to study the performance of individual components of the inlet and nozzle of the TBCC propulsion system,and finally the influence of installation on the performance of the TBCC engine was studied.First,according to the overall mission requirements,the flight envelope of the whole mission process was developed.Task analysis and constraint analysis were carried out based on the mission requirements of range,time and speed,etc.,to obtain the take-off thrust-to-weight ratio and wing load of the aircraft,and the thrust-to-weight ratio and wing load of each mission stage on the flight envelope,so as to provide data for the customization of the aircraft and engine.In order to design an external parallel TBCC engine that works stably throughout the flight envelope,the overall performance of the TBCC engine was simulated and analyzed.The design point parameters of the turbojet and the ramjet are analyzed respectively.By analyzing the off-design points of the ramjet mode,the turbine mode and the transition mode,the complete regulation rules of the three modes are obtained.Secondly,based on the osculating cones method,a simplified model of the aircraft for the study of the integration of flight and launch is developed.The lateral control design of the exhaust jet is explored to realize the lateral expansion of the exhaust flow under the fuselage.According to the selected design point parameters of TBCC engine,the design and 3D modeling of TBCC engine propulsion system were carried out by combining the wave distribution principle,flow formula and energy loss.The flow fields of single vortex jet,single punch and transition mode are calculated for the designed propulsion system,and their performance parameters are obtained.Especially for the intake system,its ability to withstand back pressure and its aerodynamic performance under the influence of back pressure are investigated.The results show that the total pressure recovery coefficient of the designed inlet can reach 0.28 and outlet Mach number 0.24 when the reverse pressure is 250 times atmospheric pressure.When the backpressure increases,the total pressure recovery coefficient of the inlet increases,but when the backpressure increases to 300 times of the atmospheric pressure,the inlet will not start.With the increase of NPR,the total pressure recovery coefficient of ramjet nozzle is basically unchanged,and the thrust vector Angle decreases,with the amplitude within 1.This is because the ramjet design point pressure ratio is high and the outlet has been overinflated.The actual thrust of the turbojet nozzle at the design point is less than the required thrust,which is caused by the decrease of the flow through the engine due to the overflow of the inlet.Finally,the numerical method was used to study the influence of installation on the aerodynamic performance of the propulsion system of the TBCC engine under typical working conditions under single turbojet and single stamping modes respectively.After installation,the performance of the inlet system in the mode of pure vortex jet and pure stamping has been improved,mainly due to the widening of the precursor after installation,the compression of the air flow in the precursor is closer to two-dimensional compression,and the reduction of the inlet overflow.In the vortex flow state,the total pressure recovery coefficient of the nozzle decreases slightly due to the disturbance of the outflow.However,in the stamping state,the outlet airflow velocity is high,and the effect of the outflow on the exhaust flow is weakened.At the same time,it verifies the feasibility of the horizontal exhaust control scheme proposed in this paper,which can generate a certain pressure gradient pointing to the central axis and restrain the lateral expansion of the nozzle.