旋翼有限地面效应的理论建模和试验

针对有限地面对旋翼产生的地面效应现象,建立了一种新的流场分析模型。根据有限地面效应问题计算量大、对旋翼流场影响不均匀的特点,使用3阶精度、高稳定性的时间步进自由尾迹格式对旋翼尾迹结构进行分析,并提出了"物质线"修正法对穿过有限地面的非物理运动尾迹节点进行了位置修正。同时开展了有限地面效应中悬停和前飞状态下的旋翼气动力测量试验,对该状态下的旋翼力和桨叶挥舞运动特点进行了测量。将新建立模型的计算结果与试验值进行对比,验证了模型的准确性。根据计算模型得到的旋翼尾迹结构,对有限地面效应中多种飞行状态下的旋翼流场进行了分析。

Theoretical model and experiment on rotor in finite ground effect

A new flow-field analysis model for the finite ground effect of the rotor is developed.Considering the complexity of the ground effect caused by finite ground,a "material line" rectification method is proposed to solve the problem that part of wake vortices may non-physically "penetrate" the finite ground in discrete prediction,and a high stability time-stepping free-wake algorithm with 3rd-order accuracy is introduced into the model.Considering the shortage of existing experimental data for finite ground effect,a finite ground effect experiment research is also implemented,and the thrust,torque and flap angle of a hovering and flying rotor are measured.The experimental data validates the analysis model proposed in this paper.According to the wake geometry got from theoretical model,several flying states of rotor in finite ground effect are analyzed,and some reasonable conclusions are gained.