舰载直升机旋翼/机体耦合动力学稳定性

Stability analysis of coupled rotor/fuselage system of shipboard helicopter

建立了舰载直升机和舰船运动耦合动力学模型,考虑了舰载直升机起落架非线性和非对称的特点,并将舰船振动自由度与旋翼/机体系统相结合分析了直升机系统耦合动力学稳定性.舰载直升机采用无轴承旋翼,用中等变形梁理论建立桨叶、柔性梁和扭矩套的有限元模型,考虑桨叶多路传力特点和桨叶根部的摆振销与变距拉杆的约束.起落架包括液压作动器和橡胶轮胎,起落架系统具有非线性特点,在不同载荷下其刚度和阻尼都不同.采用所建立的动力学模型分析了舰载直升机的"舰面共振"动力学特性,首先通过算例中的无轴承旋翼直升机"地面共振"频率与阻尼曲线验证了旋翼机体耦合模型的正确性.其次发现舰船在横摇振动情况下,旋翼/机体耦合系统的旋翼不稳定转速区域会提前出现,如果鱼叉系留则会推迟不稳定转速,并且增加系统的阻尼.

A stability analysis of a shipboard helicopter which considers the asymmetric and nonlinear landing gears, is investigated to explore the coupled dynamic behavior between the rotor and helicopter. The shipboard helicopter uses bearingless rotor, and the model of the rotor considers the large deformation of the blade, the multiple-load-path of the root of blade and the constraint of lag pin and pitch link. The undercar- riage system of helicopter which is a nonlinear system comprises the oleo and tyre. Firstly, the frequency and damp of helicopter under ＂ground resonance＂ has been calculated, and the result shows that the model is a- vailable. Then the frequency and damp of helicopter under ＂ship resonance＂ has been calculated, and the re- sult demonstrates that the rolling of ship makes the rotor/fuselage system more instability, and if harpoon is deck-lock the damping of system can be increase. That is to say the harpoon can make the rotor/fuselage sys- tem more stable on-deck.