低振动旋翼桨叶的动力学优化设计

从工程应用的角度，在桨叶气动外形参数和桨毂型式确定的情况下，探讨在设计阶段如何通过设计参数的选择设计桨叶使桨根切力最小，从而降低直升机相应的振动水平。研究了３种情况的桨叶设计：（１）控制桨叶的固有频率；（２）控制桨叶挥舞一阶振型节点位置；（３）振动水平指数最小。在分析比较的基础上给出了既能降低桨根切力减小直升机相应振动水平又能改善桨叶疲劳状况的桨叶动力学优化设计方法。

ROTOR BLADE DYNAMIC OPTIMIZATION FOR REDUCED HELICOPTER VIBRATION

Based on the theory of blade element,approximate proportional relation of some order of harmonic aerodynamic force to modal parameters is established.An index of vibration level directly pertaining to hub forces is defined in the form of modal parameters.According to this index,the measures for minimizing hub forces are proposed.With the help of the developed program BODRHV,through changing the blade spanwise mass and stiffness distribution,the dynamic design of the rotor blade is investigated in respect to the requirements of (1)natural frequencies of blade,(2)position control of first flap mode nodal point,(3) minimum index of vibration level.From the design results it is found that control of the natural frequencies is effective on aviodance of resonance,but is not effective on the reduction of hub force and corresponding helicopter vibration level.The reduction of the hub force by nearly 20 percent and the effective improvement of the fatigue state could be achieved through the rotor blade dynamic design with minimum index of vibration level under the constraints of frequencies,the position of the first flap nodal point,the total mass,the autorotational inertia and so on.