机动飞行中旋翼尾迹畸变效应实验

为准确计算机动飞行时的旋翼他轴响应,气动模型应计入尾迹畸变效应。体现此效应的关键在于推出时变的尾迹弯曲参数KR。本文通过烟流实验,得出随旋翼前进比、拉力系数和机动角速率变化的KR表达式,并分析指出,国外文献采用固定KR值不足以体现机动效应。为了给理论预测提供参考,本文还测量了机动旋翼的空气动力时间历程,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;本实验中他轴响应为主响应的15%。

Experiments of rotor wake distortion in pitching maneuvers

To compute accurately the off-axis response of maneuvering rotors,rotor aerodynamic model should introduce the wake distortion effect.The key to represent this effect is a time-accurate wake curvature parameter KR.This paper obtained a KR expression with advance ratio,rotor thrust coefficient and maneuvering angular rate as variables.Then this paper concludes that a fixed wake curvature parameter is inadequate to reflect the maneuver-related effects.Besides,the aerodynamic load history of maneuvering model rotor was tested so as to provide theoretical prediction with reference data.Experimental results show that after the rotor shaft receives a quasi-step angular input,both the rotor on-axis and off-axis aerodynamic responses assume an overshoot whose amplitude increases with the pitching rate;and that the off-axis response amplitude is about 15% of the major axis one.