Research On Design Technology Of Three-Dimensional Inward Turning TBCC Inlet

To satisfy the working demand of the future hypersonic aircraft with wide speed range,the turbine based combined cycle(TBCC)engine with advantages of high specific impulse,horizontal take-off and landing,reusable and so on,is getting more and more attention from international scientists.In view of the unique advantages of the three-dimensional inward turing inlet in the aspects of air compression efficiency and incoming flow capture ability,a design method of one kind of three-dimensional inward turing over/under TBCC inlet based on the splitter flap control mechanism was proposed in this paper.Numerical simulation and wind tunnel experiments were carried out to investigate the internal flow characteristics and trend of inlet aerodynamic performance variation under different working conditions.Firstly,a three-dimensional inward turning inlet was generated by using reversed streamline tracing in an axisymmetric internal compressible basic flow field.On this basis,a design scheme of over/under type dual-ducts inlet with working speed range of Ma=0?4.0 was proposed,and the effects of the contraction ratio and the axial ratio of the elliptical exit on the inlet performance were analyzed.The results show that the performance of the inward turing inlet can be improved by increasing the contraction ratio in a certain range.And the axial ratio of the elliptical exit will affect the performance of the inlet by changing the boundary layer thickness of the ducts.Secondly,three-dimensional numerical simulation was carried out for the inlet at design operating point and typical off-design point.The effect of different conditions such as inflow Mach number,angle of attack,sideslip angle,and back pressure produced by working engines on the performance of the inlet were analyzed.A design scheme of cowl lip spillage was proposed for the starting ability of the inlet in the whole operating range.The numerical results indicate that the inlet can capture almost all the incoming flow at design state.While at off-design state,the mass ratio can be changed by retraction of the lip movable plate,and the location of the cowl lip shock wave reflection point can be adjusted at the same time.In addition,the unsteady numerical simulation for the motion of variable geometry mechanism in the two-dimensional over/under combined inlet during the mode transition process was carried out by using the dynamic mesh technology.The results show that the performance parameters of the turbojet duct including mass ratio,total pressure recovery coefficient and Mach number decrease during the splitter flap closing process,while the corresponding performance parameters of the ramjet duct are increasing.Finally,according to the wind tunnel experiment conditions,a three-dimensional combined inlet scaling model has been designed for experiments.The results indicate that the static pressure distribution along the wall and the inlet performance variation at ramjet mode and combined mode are in good agreement with the numerical results.