垂直气流对直升机空中共振的影响研究

采用入流模型描述了非均匀定常垂直气流在旋翼上的分布．用改进的非线性VKS模型计算粘弹减摆器的复模量；分析了直升机从悬停到小速度前飞时，定常垂直气流的非均匀分布对直升机平衡操纵以及对系统摆振后退型模态阻尼的影响。分析结果表明：非均匀垂直气流对平衡时的周期变距操纵有较大影响；对减摆器具有非线性特性的直升机来说．非均匀垂直气流对其摆振后退型模态阻尼有显著影响，而减摆器具有线性特性时．则影响很小。

Influence of Vertical Inflow on Helicopter Air Resonance

An inflow-type model was applied to reflect steady non-uniform vertical flow on the helicopter rotor. Complex modulus of elastomeric lag dampers was predicted from an improved nonlinear Voigt-Kelvin series model. The influences of non-uniform vertical flow on helicopter trim controls and regressive lag modal damping levels were analyzed in hovering and forward flight. The results demonstrate that the non-uniform vertical flow changes the rotor cyclic pitch controls for trim flight and significantly changes the regressive lag modal damping arising from nonlinear characteristics of blade lag dampers.