参数化艇身阻力特性的全局敏感度及设计空间

为有效降低飞艇艇身外形设计参数的维度、提高设计效率,并给予飞艇艇身初期设计一定的参考和指导.结合PARSEC(parametric section)参数化方法、计算流体力学(Computational fluid dynamics, CFD)方法和基于方差的Sobol全局敏感度分析方法,形成了一套艇身外形参数关于阻力系数敏感度的评价体系.首先,采用物理意义明确的PARSEC方法描述飞艇艇身外形轮廓线.然后,由拉丁超立方抽样(Latin hypercube sampling, LHS)所产生样本艇身的阻力系数通过二维轴对称模型的CFD数值方法得到,CFD数值方法求解精度通过6个典型流线型旋成体的实验数据得到了验证,在保证雷诺数一致的情况下,计算和实验所得艇身阻力系数的平均相对误差为1.5%.最后,通过Sobol全局敏感度分析方法对艇身外形参数进行了敏感度排序.研究结果表明,与艇身阻力系数最敏感的3个参数分别为头部半径r_h、最大半径r_d和最大半径位置x_d.在此工作基础上形成了飞艇艇身外形的设计空间,所得设计空间对提高飞艇外形设计效率、降低飞艇气动阻力系数具有积极意义.

Global sensitivity and design space of drag characteristics of parametric airship hull

To effectively reduce the dimension of the design parameters of airship hulls, improve the design efficiency, and provide reference and guidance for the design of airship hulls in the initial stage, an evaluation system was constructed for the airship hull shape parameters associated with drag coefficient sensitivity, combined with parametric section (PARSEC) method, computational fluid dynamics (CFD) method, and Sobol global sensitivity analysis method based on variance. First, the outline of airship hull was described by PARSEC method which has clear physical significance. Then, the drag coefficient of airship hull samples produced by Latin hypercube sampling (LHS) was obtained by 2D axisymmetric CFD method. The accuracy of CFD method was verified by the experimental data of six typical streamlined bodies of revolution. Under the condition that the Reynolds number was consistent, the average relative error between the calculated and experimental drag coefficient was 1.5%. Finally, the sensitivity of the hull shape parameters was ranked by the Sobol global sensitivity analysis method. Research results show that the three parameters which were the most sensitive to the hull drag coefficient were the head radius r_h, the maximum radius r_d, and the maximum radius position x_d. On the basis of this study, the design space of the airship hull shape was formed, and the design space has positive significance for improving the efficiency of designing process and reducing the aerodynamic drag of airships.