基于弹性体变形方法的多鼓包技术在飞翼无人机耦合进排气上减阻

Drag Reduction on Multi-Bump Technology Based on Free-Form Deformation Method for Flying Wing Unmanned Aerial Vehicle Coupled with Intake and Exhaust System

关键词:  飞翼无人机  进排气系统  多鼓包  转捩模型  减阻  优化

Key words:  Flying wing unmanned aerial vehicle  Intake and exhaust system  Multi-bump  Transition model  Drag reduction  Optimization

摘要:

为进一步提升飞翼布局无人机耦合进排气系统的气动性能，针对进排气附近翼面上多鼓包开展了减阻特性与优化设计研究。基于弹性体变形思想的FFD(Free-Form Deformation，自由变形)方法，对飞翼无人机多鼓包进行有效的参数化，并构建了网格自动生成方法；结合[γ-Reθt]转捩模型进行CFD数值模拟，利用RBF代理模型及多岛遗传算法进行多鼓包优化设计。结果表明:基于FFD方法的多鼓包技术设计变量较少，优化效率高；优化后推荐鼓包构型第一个为凹鼓包，后两个为凸鼓包；多鼓包优化模型具有显著的减阻效果，迎角6°下减阻量可达6.2%，随着迎角增大，减阻效果由摩擦阻力减小为主转为压差阻力减小占据主导。

Abstract:

In order to further improve the aerodynamic performance of flying wing UAV coupled with intake and exhaust system，research on drag reduction characteristics and optimization design of the multi-bump near the wing surface of intake and exhaust system was taken. Firstly，the FFD(Free-Form Deformation) method based on the elastomeric theory was introduced. It was effective for geometry parameterization of multi-bump，and it also provided an efficient way to generate the three-dimensional flow field grid automatically. Then combined with the [γ-Reθt] transition model，numerical simulation was implemented. Finally，the RBF surrogate model and Multi-Island genetic algorithm were adopted to take an optimization on the multi-bump parameters. Results indicated that the multi-bump technology based on FFD adopts less design variable but has higher optimization efficiency. The optimized model suggests that the first bump is hollow，and the latter two bumps are convex. And it has remarkable drag reduction effect and the total drag reduction can reach about 6.2% at attack angle of 6°. With the attack angle increasing，the drag reduction influenced mainly by the friction drag leads to pressure dominated drag reduction.