耦合多螺旋桨滑流影响的低雷诺数机翼设计

以某型手抛式太阳能无人机(UAV)模型为对象进行考虑多螺旋桨滑流影响的低雷诺数机翼平面形状设计研究。首先,基于升力面理论发展了准定常求解多螺旋桨/机翼相互气动干扰问题的涡格法(VLM)程序,并采用建立参考翼型气动特性数据库的形式发展了相关低雷诺数修正(LRC)方法;然后,通过对翼型、低雷诺数机翼及单螺旋桨/机翼算例的数值模拟及与相关实验结果的对比,验证了本文数值方法具备模拟低雷诺数复杂流动问题的可靠性及准确性;最后,对某型手抛式太阳能无人机简化拉力多螺旋桨/机翼模型进行了直接优化设计及反设计,并通过具有较高精度的CFD准定常求解技术对优化结果进行了验证。结果表明:以CFD方法计算结果为参考,本文涡格法程序及低雷诺数修正方法能够准确高效地计算相关低雷诺数复杂流动问题;传统未考虑多螺旋桨滑流影响的设计机翼在实际螺旋桨工作状态下将偏离设计点,机翼气动特性得不到提高;考虑螺旋桨滑流影响的优化设计方法能够有效改善机翼阻力特性,相对应地,在设计状态下优化机翼总阻力能够降低19.52counts。

Aerodynamic design of low-Reynolds-number wing taking into account the multiple propellers induced effects

Based on a certain hand-throw solar-powered unmanned aerial vehicle (UAV),the optimization design approaches for low-Reynolds-number wing coupled with multiple propellers induced effects are studied.The corresponding quasisteady procedure based on the vortex lattice method (VLM) of lifting line theory and the low Reynolds correction (LRC)method based on the reference airfoil aerodynamic properties database are developed to simulate the multiple propellers/wing aerodynamic interference at low Reynolds numbers.The reliability and accuracy of the simplified numerical method (VLM procedure and LRC method) are testified with several cases studies and their comparison with experimental results.Both the direct optimization design and inverse design of the simplified hand-throw solar-powered UAV model in tractor configuration are conducted,and the optimization results are examined with high-accuracy CFD technique.It shows that (a) the low-Reynolds-number flow can be simulated by the VLM-LRC method efficiently and accurately;(b) the aerodynamic properties of the optimal wing cannot be improved when the propeller slipstream effect is not taken into consideration in the conventional design approach;(c) the wing drag performance can be greatly improved with the optimization approach that takes into account the multiple propeller slipstream effects,and the optimized wing has a drag reduction of 19.52 counts at the design state.