共轴式直升机双旋翼系统的多体动力学模型

Multibody Dynamic Model of Dual Rotors System in Coaxial Helicopter

建立了共轴式直升机双旋翼系统结构的多体动力学模型,该细节模型包括旋翼轴内轴与外轴、桨毂、双旋翼、操纵杆、自动倾斜器、驱动器和固定支架等所有关键部件,经过分析计算,得到了关键部件与旋翼系统结构运动耦合的的动力学特性。与台架运转振动测试的结果进行对比发现,误差基本都在5%以内,验证了这种基于多体动力学的分析方法在共轴式直升机复杂系统结构动力学设计中应用的可行性。

At the beginning of 1990 s, the Seagull helicopter was designed and manufactured in Beihang university. Itis a coaxial helicopter with dual rotors installed upside and underside of one rotor shaft. Thetwo rotors are coaxial and contra-rotating for compensating each other' s torque that they apply to the helicopter airframe when they rotate. Without a tail rotor, the coaxial configuration has a more compact structure. Meanwhile, itincreases the complexity of the main rotor system′s structure. Although it gained a huge success in its first flight in 1995, and subsequently passed many flying performance′s tests, the engineers did so little theoretical analysis that they wasted a large number of time and cost in repeated experiments. Furthermore, due to lack of essential theoretical calculation and analysis, subsequent improvement of it had become very difficult. The multibody dynamics analysis is cast within the framework of nonlinear finite element methods, and the element library includes rigid and deformable bodies as well as joint elements. Dual rotor system of coaxial helicopter is modeled by multibody dynamics approach in this paper, and the detailed models include rotor shaft, hub, dual rotor blades, pitch links,swashplate, actuators which are attached to the pylon. Through calculation and analysis of models,dynamics characteristics of key sub-component structures and the kinematic couplings of rotor system are obtained. Subsequently, analytical data is compared with experimental data obtained in platform experiments, and each error of them is less than 5%, which validates the feasibility of the multibody dynamics analysis method′s application in the dynamic design of complicated system structure in coaxial helicopter.