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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。
In order to accomplish a specific mission, the stratospheric airship needs to overcome the wind field to maintain a long-term fixed point, thus requiring its resistance to be minimized. The total resistance of the airship in the boat body resistance accounted for 60-70%, so the airship, the hull shape research to obtain resistance is small and the actual shape is very important. In this paper, the potential flow-boundary layer coupling method and hybrid genetic algorithm are used to optimize the shape of the airship of the airship. The external potential flow is solved by the Hess-Smith face element method which distributes the point sources on the hull surface. The boundary layer method uses the integral boundary layer method and the drag coefficient is calculated by the Squire-Young method. The optimal shape is obtained by a hybrid genetic algorithm consisting of genetic algorithm and Nelder-Mead simplex method. Through the optimization analysis, a practically available optimized shape is obtained, which has the advantages of relatively small drag coefficient in both turbulence and laminar flow regimes.