Research On Drag Reduction And Cooling Technology Of Hypersonic Vehicles Based On Surface Micro-structure

With the rapid development of the vehicle, the aerodynamic heating becomes the key research question of hypersonic vehicles’design and development. When the vehicle flies by supersonic or hypersonic, due to the viscous blocking effect of air, the air in the boundary layer has a large velocity gradient which leads to the air layer produce strong friction. The strong aerodynamic friction makes the temperature near the wall rise sharply. The high temperature air keeps transferring heat to low temperature wall of the vehicle, then causes the strong aerodynamic heating. This may lead to the vehicle’s structure shape ablation, structural strength and stiffness changing. This brings serious impact on the normal flight of hypersonic vehicle and security issues.Recently the micro-structure drag reduction technology has made great progress. In this paper, research status and progress of the micro-structure of the drag reduction technology were summarized. By analyzing the mechanism of turbulence and structure of the model of turbulence near the wall, the mechanism of drag reduction from micro-structure was discussed in two aspects,"the Second Vortex" theory and "the Protrusion Height Theory". A lot of testing and practical applications proved the feasibility of drag reduction of micro-structures. This paper attempted to apply micro-structure technology to the surface of hypersonic vehicle, and observed the effect of surface micro-structure on hypersonic vehicle heating reduction.Firstly, we found that when using triangle micro-structure, with two-dimensional simulation, the average velocity of front wall reduced to15.67m/s; the average velocity of rear wall reduced to24.49m/s. So using triangle micro-structure can greatly reduce the wall friction drag.In addition, the paper adopted the soft of Computational Fluid Dynamics, Fluent to simulate overall aerothermal of a certain type vehicle, and compared the vehicle aerothermal situation with different environmental parameters and flight Mach number.Finally, based on these studies, we added the surface micro-structure on the rudder wing and researched the effect of the existence of surface micro-structure to the flow field characteristics, especially the impact of the boundary layer near the wall. And then analyzed of surface micro-structure’s effects on aerodynamic heat flux. Throw the simulation, we found when adding along-flow-through micro-structure of the rudder the average temperature was909K, compared to non-micro-structure(933K), the temperature reduced24K, the cooling rate was2.57%. By comparing different sizes and shapes of the surface micro-structure, finally obtained the best cooling effect of the micro-structure.All analysis on mechanism of surface micro-structure turbulent boundary drag and numerical simulation calculations in the paper, there will be important significance and reference to the further research in this field.