Research on the forward flight performance of rotor based on variable-droop leading edge

Congcong Li,Yongjie Shi,Xingliang Liu,Guohua Xu

doi:10.1051/jnwpu/20213930668

Abstract

Aiming at the dynamic stall phenomenon of the retreating side of the rotor in forward flight, the existing flow control method of dynamic leading edge droop was applied to the flow control of forward-flying rotor at three-dimensional scale. A numerical simulation method based on variable droop leading edge is established in this paper. The seesaw rotor is taken as the research object, the moving overset mesh method and RBF grid deformation technology are used, the integral form of Reynolds average N-S equation is the main control equation. The influence of the dynamic leading edge at r/R=0.75~1 on the aerodynamic characteristics of the rotor when the forward ratio is 0.3 is investigated. It is found that variable droop leading edge on the retreating side can effectively inhibit the generation and development of separation vortices near the trailing edge, and has a significant effect on lifting lift coefficient and section normal force coefficient, reducing torque coefficient, and thus improving the equivalent lift-drag ratio of the rotor. In a certain range, the control effect is better with the increase of the droop amplitude under the leading edge.

Highlights

针对三维旋翼的研究,为了综合考虑计算成本, 本文选用 2 片矩形桨叶,翼型采用 OA209,旋翼半径 R = 2.1 m,弦长 c = 0.2 m,线性负扭转为- 4.8° / m。计算状态:桨尖马赫数为 0.647;前进比为 0.3。经过配平得到相应的周期变距 θ = 12.5° - 6.3° sinψ + 1.1° cosψ。本文分别针对前缘下垂幅值 δm 为 5°,8°,10° 进行研究,k∗均取 2,以防止由于较大的前缘下垂启停加速度而给桨叶带来振动等不利影响。当前缘下垂时,该部分的相对迎角减小,为避免迎角较小的前行侧桨叶由于前缘下垂而造成一定的升力损失,本文仅对后行侧桨叶设置前缘下垂的运动。前缘下垂规律随方位角的变化如图 6 所示。图 7 给出了基准状态桨叶与前缘下垂角为 10° 时桨叶前缘的对比图。使用 RBF 网格变形方法使前缘下垂 10° 后,桨
Research on the forward flight performance of rotor based on variable⁃droop leading edge
Aiming at the dynamic stall phenomenon of the retreating side of the rotor in forward flight, the existing flow control method of dynamic leading edge droop was applied to the flow control of forward⁃flying rotor at three⁃di⁃ mensional scale

Summary

Introduction

针对三维旋翼的研究,为了综合考虑计算成本, 本文选用 2 片矩形桨叶,翼型采用 OA209,旋翼半径 R = 2.1 m,弦长 c = 0.2 m,线性负扭转为- 4.8° / m。计算状态:桨尖马赫数为 0.647;前进比为 0.3。经过配平得到相应的周期变距 θ = 12.5° - 6.3° sinψ + 1.1° cosψ。本文分别针对前缘下垂幅值 δm 为 5°,8°,10° 进行研究,k∗均取 2,以防止由于较大的前缘下垂启停加速度而给桨叶带来振动等不利影响。当前缘下垂时,该部分的相对迎角减小,为避免迎角较小的前行侧桨叶由于前缘下垂而造成一定的升力损失,本文仅对后行侧桨叶设置前缘下垂的运动。前缘下垂规律随方位角的变化如图 6 所示。图 7 给出了基准状态桨叶与前缘下垂角为 10° 时桨叶前缘的对比图。使用 RBF 网格变形方法使前缘下垂 10° 后,桨 5%, 但随着 VDLE 的下垂幅值 δm 的增加,等效升阻比并没有持续显著增加,δm 为 8°和 10°时的等效升阻比区别并不明显。 [2] SAHIN M, SANKAR L N, CHANDRASEKHARA M S, et al Dynamic stall alleviation using a deformable leading edge concept⁃

Results

Conclusion