| For an aircraft with aircraft/propulsion integrated design,the lower surface of the forebody is a pre-compression system for the inlet and the lower surface of the afterbody is the expansion system of the engine.This design make the forebody and the afterbody of the aircraft have a great influence on the efficiency of the engine,and the engine outlet flow status will determine the pressure distribution of the afterbody,and then change the comprehensive push-resistance characteristics of the aircraft.As a consequence,the aircraft with an integrated design often exhibit strong coupling,nonlinearity and other characteristics.In this paper,the influence law of the inlet design parameters on the comprehensive push-resistance characteristics of the aircraft is studied by establishing the mathematical model of aircraft aerodynamic force and ramjet engine.On this basis,the design method of integrated waverider forebody and Two-dimensional TBCC inlet is studied.At the same time,a variable geometry structure that can be applied to the Two-dimensional TBCC inlet is designed.The aerodynamic performance of the integrated 2D TBCC inlet at each typical working mode was studied by three-dimensional numerical simulation.The details are as follows.Firstly,the aerodynamic approximation model is used to analyze the flow characteristics and distribution in the longitudinal section of the aircraft.The aerodynamic force and moment generated relative to the reference coordinate system in the aircraft are calculated and the corresponding approximate model is established.According to the integrated design requirements of aircraft/propulsion system,the mathematical model of airbreathing ramjet engine is established and the influence of intake system design parameters(total deflection angle and lip angle)on the performance of propulsion system and the general thrust-resistance characteristics of the aircraft is analyzed.Secondly,based on the shear flow theory,a multi-stage waverider is generated,and then a 2D inlet integrated with a wave rider forebody is designed.The numerical simulation results show that this forebody can effectively improve the lift-drag ratio of the aircraft,reduce the lateral overflow of the outer compression section,and increase the inlet flow coefficient.A variable geometry mechanism of two-dimensional TBCC inlet is designed.The entire mechanism maintains the smooth transition of the compression section during the flight,avoids unnecessary expansion,and realizes the function of changing the inlet geometry surface and enlarging the throat area.Then,the three-dimensional numerical simulation is used to study the flow field and aerodynamic performance of two-dimensional TBCC inlet under the typical working mode.At Mach 4.0,the inlet flow coefficient was 0.92,the average Mach number at the exit of the ramjet channel was 0.27,and the average total pressure recovery factor of it was 0.47.When the inlet is working on the ramjet mode,the flow coefficient is about 0.65 ~ 0.92,the total pressure recovery of the exit of the ramjet channel is not less than 0.47;When the inlet is working on the turbo mode,the flow coefficient is about 0.65 and the average total pressure recovery coefficient at the exit is not less than 0.75.At last,the flow field characteristics and aerodynamic performance of the TBCC inlet under different splitter plate degrees are analyzed by constant numerical simulation.When the TBCC inlet is working on the transitional mode,the working mode is mainly switched by adjusting the splitter plate.The performance of the single channel and the capacity of sustain the back pressure are usually positively correlated with the channel mass flow.When the terminal shock has not crossed the splitter plate,the ramjet channel and the turbo channel do not interfere with each other.After the terminal shock through the splitter plate,the terminal shock will affect the flow distribution of the two channels,thus affecting its aerodynamic performance. |
PDF Full Text Request