共轴刚性旋翼桨毂阻力特性及流动机理

共轴刚性旋翼直升机在高速飞行时,桨毂流动复杂、分离强、阻力大。为明晰其阻力特性和流动机理,采用CFD方法针对已完成风洞试验的共轴桨毂组合模型进行数值模拟研究,获得了桨毂组合模型各单独部件的阻力、表面流动和空间流场特征,阐明了产生阻力最大的部件和影响阻力的主要因素,揭示了中间轴整流罩和塔座设计参数的减阻机制。分析结果表明:上、下旋翼桨毂是产生阻力的主要部件;中间轴和塔座的分离尾流对桨毂表面流动产生较大的干扰作用,使桨毂整流罩表面受干扰区域产生气流分离;具有较缓和逆压梯度的中间轴整流罩和塔座能有效减小分离尾流对桨毂整流罩的干扰,从而降低整个共轴桨毂系统的阻力。

Drag Characteristics and Flow Mechanism for Coaxial Rigid Rotor

When the coaxial rigid rotor helicopter is flying at high speed, the hub has complicated flow, strong separation and large drag. In order to clarify its drag characteristics and flow mechanism, the CFD method is used to carry out numerical simulation research on the coaxial rotor hub model which has been tested in wind tunnel. The drag distribution, surface flow and spatial flow field characteristics of each component of the rotor hub are obtained. The components with the greatest drag and the main factors influencing the drag are explained. The drag reduction mechanism of the design parameters of the intermediate shaft fairing and pylon is revealed. The analysis results show that the hub of the upper and lower rotor blades is the main component of drag.The separation wake of the intermediate shaft and pylon has a great interference effect on the surface of the hub faring, which causes the flow separation on the surface of the hub fairing.The intermediate shaft fairing and pylon with moderate reverse pressure gradient can effectively reduce the interference of the separated wake flow to the hub faring and reduce the drag of the whole coaxial rotor hub system.