平流层飞艇艇身外形研究

摘要

为了完成特定的任务,平流层飞艇需要克服风场保持长期定点,因此要求其阻力最小.飞艇总阻力中艇身阻力占60-70%,因此对飞艇而言,针对艇身外形进行研究得到阻力小而且实际可用的外形是非常重要.本文采用势流-边界层耦合方法与混合遗传算法对平流层飞艇艇身的外形进行了优化.外部势流采用在艇身表面分布点源的Hess-Smith面元法求解,边界层计算采用积分边界层方法,阻力系数采用Squire-Young方法计算得到.最优外形通过由遗传算法和Nelder-Mead单纯形法组成的混合遗传算法优化得到.通过优化分析得到了一种实际可用的优化外形,具有在湍流和层流两种流态下阻力系数都比较小的优点.%The stratosphere airship must overcome the wind field for the purpose of keeping station for a certain specific mission. Thus, it is necessary for airship to minimize the drag. The drag of the airship hull accounts for about 2/3 0f the total drag. It is very important to obtain the shape of airship hull with minimum drag, and used in the practical condition.Using an inviscid-boundary layer model and a hybrid genetic algorithm, the shape optimization of airship hull is considered in this paper. The inviscid flow is computed by using point sources distributed airship surface. The boundao layer is computed hy using an integral formulation. The drag coefficient is computed by using the Squire-Young formula. OpLimization problems are solved by using a hybrid genetic algorithm composed of Cenetic Algorithm and Nelder-Mead simplex search method. The optimized shape has minimum drag under the condilion of turbulence and laminar flows and can be used in the practical condition.