Study on design of low Reynolds number reflexed airfoil for solar-powered UAV in flying wing configuration

飞翼布局太阳能无人机低雷诺数反弯翼型设计

School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072, China

Received: 3 September 2021

Abstract

Based on the application requirements of a small hand-launched solar-powered unmanned aerial vehicle (UAV) in flying wing configuration, the optimization design of the low Reynolds number (LRN) reflexed airfoil is carried out in this study to meet several requirements such as high lift, mild stall, demanding pitching moment. Firstly, the accuracy and reliability of both quasi-steady and unsteady numerical methods to simulate the LRN transition flow and the stall separated flow at large angles of attack (AOA) are validated by an airfoil case study at specified Reynolds numbers; Secondly, the LRN reflexed air-foil optimization design framework is established by using the CST parameterization method, the multi-island genetic algorithm (MIGA), and the kriging surrogate model; Lastly, the LRN reflexed airfoil optimization study is conducted by using the NACA 8-H-12 reflexed airfoil as the baseline airfoil, it shows that both the lift-to-drag performance and the stall characteristics of the designed airfoil is significantly improved when compared with the baseline airfoil, which are quite beneficial for the small hand-launched solar-powered UAV in flying wing configuration to realize the hand-launched take off and the high-lift long-endurance flight.

摘要

基于某手抛式小型飞翼布局太阳能无人机的应用需求, 开展俯仰力矩约束下高升力、失速和缓的低雷诺数反弯翼型优化设计研究。结合特定低雷诺数下翼型算例, 验证了准定常和非定常数值模拟方法求解低雷诺数转捩流动问题和大迎角失速分离流动问题的准确性和可靠性; 基于CST参数化方法、MIGA优化算法、Kriging代理模型等搭建了低雷诺数反弯翼型优化设计框架; 以NACA 8-H-12反弯翼型作为基准进行优化设计研究, 结果表明: 优化翼型在大迎角状态下的失速特性及升阻特性得到显著改善, 设计结果有利于小型飞翼布局太阳能无人机的手抛式起飞及高升力长航时飞行。