Applied Research Of LES And Aerodynamic Performances Analysis Of The Lightcraft

The applied research of Large Eddy Simulation (LES), the shape optimization and the aerodynamic performances analysis of the lightcraft propelled by laser are main content in this paper.The LES developed history and the present domestic and foreign researching situation were analyzed. The LES developing tendency, the implicated characteristics and the insufficiency were primarily summarized. Based on the incompressible LES theoretical analysis, the compressible LES governing equations that can be applied universally in astronautics domain were derived. Combined NND and WENO schemes, the program was constructed using Smagorinsky model with the near wall modified equations. The program has been applied to the problem of nozzle. This preliminary can examined the procedure's rationality. The flowfield with separation area and no separation area were studied to decide the necessary of using LES. The supersonic blunt and back-facing step flowfield was simulated. The results compared with the Reynolds average results using commercial software. For the supersonic blunt flow which doesn't have separated areas, the difference of LES result and Reynolds average result was not distinct. But for the supersonic back-facing step flow which has separated areas, the LES excelled the Reynolds average result, explained the supersonic blunt flow that having no separation areas high accuracy could also to be obtained without LES, but the supersonic back-facing step flow that have separation areas using the LES can obtain the high accuracy.The basic principle and characteristics of laser propulsion were analyzed. The flowfield analysis and the shape optimization of the lightcraft were carried on. The optimized shape in the parameter range was obtained. In order to studied the lightcraft's flight performance, the 3-D lightcraft aerodynamic performance research at different altitudes, velocity and angle of attack were simulated. In subsonic situation, the drag coefficient was reducing with the angle of attack increasing, but in supersonic situation, the drag coefficient was increasing with the angle of attack increasing. Fixed the angle of attack, in subsonic situation, the drag coefficient was reducing with the velocity increasing; in supersonic situation, the drag coefficient was increasing with the velocity increasing.