Variable Geometry Design And Aerodynamic Performance Research Of TBCC Inlet

The TBCC propulsion system based on the two-dimensional inlet is with simple variable geometry and it is easy to implement.Referring to the design experience of its expansion split flowpath,the Internal Wave-Rider(IWR)inlet with strong flow capture capability and high compression efficiency can be applied to the TBCC propulsion system.Firstly,this paper designs a variable geometry TBCC inlet based on an integrated two-dimensional inlet,studies the influence of the split flowpath design parameters on the inlet performance and studies the flow characteristics by numerical simulation.Subsequently,the IWR inlet is applied to the TBCC propulsion system,a variable geometry scheme suitable for its three-dimensional compression surface is designed to ensure that the throat maintains a rectangular shape;referring to the variable geometry and design parameters of the two-dimensional TBCC inlet,the expansion split flowpath of the IWR TBCC inlet is designed,and the flow characteristics in different working modes are performed.1.In order to design the integrated two-dimensional inlet for TBCC propulsion system,the side plate and the forbody configurations are studied.The side plate with folding leading edge can improve the internal quality by increasing the overflow of the boundary layer,and reduce the mainstream overflow at the same time.The inlet integrated with a wave rider forebody with proper width can ensure the internal flow performance and reduce the drag of the aircraft.2.This paper designs a two-dimensional TBCC inlet with smooth transition variable geometry and studies the design parameters of the split flowpath on the flow characteristics.With a large expansion angle,the separation zone in the flowpath is large and the exit performance is poor;with a small expansion angle,the exit performance of each state is good,but the structure of the inlet is heavy.When the length of the splitter is large,the separation zone is near the terminal shock resulting in a large loss in the design state;when the length of the splitter is too small,it is easy to form a separation zone in the turbine passage in Mach 2.5 and then reduce the quality of the airflow.3.The flow characteristics of two-dimensional TBCC inlet are studied.The inlet flow coefficient is between 0.59 and 0.86;the total pressure recovery at the exit in ramjet mode is 0.53~0.81;in transition mode,the total pressure recovery at the exit of turbine/ramjet passage is 0.73~0.85/0.75~0.79.In transition mode,the flow separation in turbine passage is improved by increasing its opening,while the exit parameters of ramjet passage do not decrease too much,which can balance the demands of the downstream engines.4.Applying the IWR inlet to the TBCC propulsion system,a variable geometry scheme is proposed which is suitable for its three-dimensional compression surface and ensure its throat maintaining rectangle.At the side wall of IWR inlet,bypass passages are added.And open the bypass passages to ensure the inlet starts successfully in the low Mach states.Referring to the design experience of two-dimensional TBCC inlet,the expansion split flowpath of the IWR TBCC inlet is designed and the complete IWR TBCC inlet is obtained.5.The flow characteristics of the IWR inlet are studied.The flow coefficient is between 0.8 and 0.997,and full flow capture is almost achieved in the design state.In ramjet state,the total pressure recovery at the exit is 0.45~0.84.In transition state,the total pressure recovery at the exit of the turbine passage is 0.8~0.89 and the value at the exit of ramjet passage is approximately 0.7.