大机动飞行中孤立旋翼的非定常空气动力模型

为提高旋翼他轴响应的预测，气动模型应当计入机动旋翼的尾迹畸变效应，而准确表示尾迹弯曲参数Kn是关键。为表达机动导致的各种效应，增广Peters-He有限状态尾迹模型可以吸收随飞行状态变化的Kn值。根据烟流实验，该参数随旋翼前飞速度、拉力和机动角速率而变化。旋翼的空气动力实验表明，旋翼轴接受准阶跃输入后，同轴及他轴的空气动力响应有过冲，且俯仰速率愈大，过冲幅值愈大。理论和实验结果的对比显示，为了正确计算机动飞行中的旋翼气动力，特别是操纵的他轴响应，应在模型中采用随状态变化的尾迹弯曲参数Kn。此外，在当前模型基础上联合动态尾迹畸变模型，计算出的旋翼力和力矩更接近试验数据。

UNSTEADY AERODYNAMIC MODEL OF ISOLATED ROTOR IN LARGE-AMPLITUDE MANEUVERS

To improve the rotor off-axis response prediction, aerodynamic models must include the wake distortion effects of the maneuvering rotor. And the crux of the matter is to obtain a precise wake curvature parameter KR. A Peters-He finite-state wake model is improved to incorporate the operating-state-dependent KR to embody maneuver-induced effects. The curvature parameter KR varies with rotor forward speed, thrust and maneuvering angular rate according to a smoking experiment. Moreover, aerodynamic force/moment experiment indicates that after a quasi-step angular input, both on-axis and off-axis rotor responses show that an overshoot and its amplitude increases with the pitching rate. The comparison between theoretical and experimental results shows that the operating-state-accurate curvature parameter must be adopted to obtain accurate aerodynamic forces/moments, especially for the off-axis response. Additionally, combined with a dynamic wake distortion model, the obtained correlation agrees well with experimental data.