Numerical Study Of Energy Deposition Technique For Drag Reduction And Aerodynamic Heating At Hypersonic Speeds

The energy deposition technique is an effective method for drag reduction by adding heat source into the upstream in front of vehicle, which induces early separation in the flow and provides low pressure region ahead of vehicle. It may keep the original shape of vehicle and has the advantages of controllable, robust, and high drag reduction effect. As a result of which, it has been considered as a very promising method for reducing drag, and been paid more and more attention. As we all known, all of heat source strength, location and attack angle of vehicle are important factors that influencing drag reduction effect. The research on these factors has great significance for obtaining high drag reduction rate and energy efficiency and thermal protection of vehicle.In this thesis, the numerical simulation of the flow field of hypersonic vehicle is carried out. Standard k-ε turbulence model is used and the Navier-Stokes equations are solved. In this thesis, energy injection is achieved through the simulations of high temperature heat source in front of the lifting vehicle model, thus forming the heating area. Beyond that, the numerical simulations of hemispheric model and lifting body model in flight at Mach 6.5 is carried out and the analysis of the principle of energy deposition for drag reduction and the factors affecting the aerodynamic drag of the lifting vehicle, such as the strength and location of heat source and the angle of attack, is conducted.The results show that energy deposition method can significantly reduce the shock resistance by introducing interaction between shock wave after the source and bow shock in front of vehicle. However, if shock wave drag of vehicle’s head accounts for only a small proportion due to the excessive windward area, the method cannot obtain such high drag reduction rate. With the increase of the heat source strength, the coupling between the shock wave of the heat source and the initial shock of the vehicle is enhanced, the drag reduction rate increases gently. When the heat source strength increases to a certain value, the drag reduction rate basically stays the same. The energy of the heat source is absorbed into the flow field near the vehicle, thus increasing the wall temperature of the vehicle. The distance between the heat source and stagnation point on the head of the vehicle has a significant influence on the drag reduction and the optimal distance exists. The angle of attack affects the windward area and the wave interaction, thus affecting the effect of drag reduction. The reduction rate and energy efficiency decreased while attack angle increases. When the angle of attack increases to a certain level, the energy deposition method completely loses the effect of drag reduction.The results obtained in the thesis provide important theoretical support and reference on energy deposition technique for drag and heat flux reduction of hypersonic vehicles in engineering applications and related experimental studies.