Numerical Simulation on Aerodynamics of Multi-Element Airfoil with Drooped Spoiler in Ground Effect

带扰流板下偏的多段翼型地面效应数值模拟

¹ School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072, China
² Department of Floating Platform, No. 38 Research Institute of CETC, Hefei 230088, China
³ Unmanned System Research Institute, Northwestern Polytechnical University, Xi’an 710072, China
⁴ AVIC Aerodynamics Research Institute, Sheng yang 110034, China

Received: 1 February 2018

Abstract

By using the finite volume method and k-ω SST turbulence model to solve the Reynolds Average Navier-Stokes equation and using the slipping wall to simulate the relative movement of the ground, the ground effect on the aerodynamic characteristic of multi-element airfoil with drooped spoiler is investigated numerically, and the reason why the lift coefficient decreased in ground effect is analyzed. The results indicate that, with the reduction in ride height, the lift and the drag decrease and the lift-drag ratio increases for the multi-element airfoil; the amplitude of the reduction in the lift coefficient increases with the reduction in ride height and the increase in the angle of attack, the maximum of lift coefficient can be reduced by about 22%; with the effect of ground, the losses of suction at upper surface make the lift decrease, the increases of pressure at lower surface make the lift increase, the variation of the lift coefficient for the main wing caused by the former is more than three times that of the latter. Analyzing the reason why the lift coefficient decreases showed that:on the one hand, ground effect on the lift coefficient for clean airfoil is changed with the range of angle of attack. For the low-to-moderate angle of attack, the lift coefficient increases; for the high angle of attack, the lift coefficient decreases. But multi-element airfoil works in the takeoff and landing stage for the high angle of attack, which causes the reduction of the lift coefficient in ground effect. On the other hand, the increase of the lift coefficient caused by the deflection of spoiler decreases with the reduction in ride height and the maximum reduction can be about 50%, which illustrates that ground effect makes interaction of the front and back section for the multi-element airfoil weak, resulting in further decreasing the coefficient for the multi-element airfoil.

摘要

采用有限体积法和k-ω SST湍流模型求解雷诺平均N-S方程，使用运动壁面边界条件模拟地面的相对运动，研究了地面效应对带扰流板下偏的多段翼型气动特性的影响，并分析了地效影响下升力系数减小的原因。结果表明：随着离地高度的减小，多段翼型的升力和阻力减小，升阻比有所增大；升力系数的减小幅值随着离地高度的减小和迎角的增大逐渐增大，最大可以减小22%左右；地效影响下，主翼上表面吸力减小导致的升力系数减小幅值是下表面压力增大导致的升力系数增大幅值的3倍以上。升力系数减小原因分析表明：①地面效应对干净翼型升力系数的影响与迎角范围有关，在中小迎角下升力系数增大，在大迎角下升力系数减小，而多段翼型往往工作在大迎角下的起降阶段，故其升力系数在地效作用下减小；②扰流板下偏前后的升力系数增量随着离地高度的减小而减小，最大减小量可以达到50%左右，说明地面效应使得多段翼型前后部件之间的增升作用减弱，从而导致多段翼型的升力系数进一步减小。