构型参数对共轴刚性旋翼悬停气动干扰的影响机理

Influence mechanism of configuration parameters on the aerodynamic interaction of rigid coaxial rotor in hover

基于非定常雷诺平均Navier-Stokes方程和嵌套网格法建立了共轴刚性旋翼流场模拟方法,通过与单旋翼对比,深入分析了其气动干扰特征和形成机理,并探究了旋翼间距和转速对共轴刚性旋翼悬停气动干扰的影响机制。结果表明:桨叶相遇干扰引起的拉力波动主要取决于桨叶附近诱导流场的梯度,在悬停状态,桨叶上方、桨尖附近的流场梯度较大,因此上旋翼拉力脉冲幅值大于下旋翼,桨尖附近剖面的拉力波动大于桨根处;随着间距从基准间距逐渐增大,桨叶相遇干扰迅速减弱然后消失,周期诱导效应则逐渐减弱,但在大间距时仍然存在;旋翼转速增加会增强诱导流场强度,从而引起更大的拉力波动。

A flow field simulation method for rigid coaxial rotor is established based on the unsteady Reynolds-Averaged Navier-Stokes equations and the overset grid method.By comparing with a single rotor,the aerodynamic interaction characteristics and formation mechanism are analyzed.The influence mechanism of rotor spacing and speed on the aerodynamic interaction of rigid coaxial rotor in hover is investigated.Results show that the thrust fluctuation caused by the blade-meeting interaction mainly depends on the gradient of the induced flow field near the blade.In the hovering state,the flow field gradient near the blade tip and above the blade is large,so the amplitude of the upper rotor thrust pulse is greater than that of the lower rotor.The thrust fluctuations of the sections near the blade tip are greater than those near the blade root.As the spacing gradually increases from the basic spacing,the blade-meeting interaction weakens rapidly and then disappears,while the periodic induced effect gradually weakens but still exists at large spacing.With the increase of rotor speed,the intensity of the induced flow field is enhanced,leading to greater thrust fluctuations.