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

基于动态前缘下垂的提升旋翼前飞性能的研究

Received: 10 October 2020

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.

摘要

针对直升机前飞时后行侧桨叶的动态失速现象，将目前已有的动态前缘下垂的流动控制方法应用于三维尺度的前飞状态旋翼流动控制中，建立了基于动态前缘下垂的提升旋翼气动性能的数值模拟方法。以跷跷板式旋翼为研究对象，使用运动嵌套网格方法及基于径向基函数的网格变形技术，积分形式的雷诺平均N-S方程为主控方程。探究了桨叶r/R=0.75~1处的前缘动态下垂对前进比为0.3时的旋翼气动特性的影响。研究发现，在后行侧使用动态前缘下垂可以有效抑制桨尖附近分离涡的生成和发展，对提升旋翼的升力系数和剖面法向力系数、降低扭矩系数，从而提升旋翼的等效升阻比有显著作用。在一定的范围内，随着前缘下垂幅值的增加，控制效果更好。