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低碳环保的电动飞机在要求较高升阻比的同时,需要尽量降低成本、缩短研制周期。但高精度的数值模拟时间代价很大,因此针对电动飞机翼型设计中初始翼型较难选取、优化速度较慢的问题,提出了一种基于变精度遗传算法的翼型多点快速优化方法。以常用的Hicks-Henne型函数为基础,改进了其对翼型后缘描述不精确的问题。在数值模拟阶段,介绍了一种快速气动参数计算软件XFOIL,并分析了该软件的适用性与局限。之后给出了使用XFOIL与Matlab进行联合求解的方法,在无人干预的情况下完全实现了翼型设计与优化的自动化,提高了设计效率。在翼型优化阶段,为保持较高的精度和寻优效率,设计了翼型参数的实数编码方法。针对传统遗传优化算法了改进,设计了染色体变精度杂交方法以及动态惩罚方法。最后,给出了基于遗传算法的多点优化方案,以及翼型多目标快速优化一体化设计方案。仿真分成两部分进行,首先改进的Hicks-Henne型函数能够有效实现参数化翼型的后缘夹角改变。通过与NSGA-II方法的优化结果对比,本文的方法在一定迭代次数范围内获得的升阻比更高,失速特性更加缓和,特别是在综合提高翼型优化效率方面表现较好。仿真结果表明,该方法能够快速获得多种工况下具有较高升阻比的翼型,也可以作为进一步优化的初始翼型,能提高翼型优化效率。
Low-carbon and environmentally friendly electric aircraft require a higher lift-resistance ratio at the same time, we need to minimize costs and shorten the development cycle. However, high-precision numerical simulation time is very expensive. Therefore, aiming at the problem that the initial airfoil in electric airfoil design is difficult to select and the optimization speed is slow, a multi-point rapid optimization method based on variable precision genetic algorithm . Based on the commonly used Hicks-Henne type function, the problem of imprecise description of the trailing edge of the airfoil is improved. In the numerical simulation stage, XFOIL, a fast aerodynamic parameter calculation software, is introduced and the applicability and limitations of the software are analyzed. After that, the method of joint solution using XFOIL and Matlab is given, and the airfoil design and optimization are fully automated and the design efficiency is improved without any intervention. In the airfoil optimization stage, in order to maintain high accuracy and optimization efficiency, a real coding method of airfoil parameters is designed. Aiming at the improvement of the traditional genetic algorithm, the method of hybridization of chromosomal variable precision and the dynamic punishment are designed. Finally, a multi-point optimization scheme based on genetic algorithm and an airfoil multi-target rapid optimization integrated design scheme are given. Simulation is divided into two parts, the first improved Hicks-Henne type function can effectively achieve the parameterized airfoil trailing edge angle change. Compared with the optimized results of NSGA-II method, the proposed method achieves a higher lift-drag ratio and stalling characteristics in a certain number of iterations, especially in the overall improvement of airfoil optimization efficiency. The simulation results show that this method can quickly obtain airfoils with high lift / drag ratio under various operating conditions, and can also be used as the initial airfoil optimized further to improve the airfoil optimization efficiency.