旋翼转速优化直升机的纵向操纵性与稳定性分析

针对不同旋翼转速、桨叶弹簧刚度、平尾面积对旋翼转速优化(OSR)直升机操纵性、稳定性的影响,建立了飞行动力学模型,该模型以自由尾迹计算旋翼入流,考虑了旋翼尾迹对其他气动部件的干扰,最后利用差分法计算直升机的气动导数及操纵导数矩阵.结果表明:旋翼转速的减小,降低了直升机的操纵性,增加了旋翼的迎角稳定性,但增加桨叶根部弹簧刚度则会提高直升机操纵性,同时也会使得稳定性下降;而旋翼转速优化直升机的无平尾设计虽然降低了直升机的纵向稳定性,使得样例直升机处于飞行品质规范ADS-33E中的第3级水平,由此带来的不稳定模态的振荡发散周期较长,并且取消平尾后提高了直升机的操纵性,通过飞行控制系统完全可以抑制,因此无平尾设计方案对旋翼转速优化直升机而言仍然是可接受的.

Analyze on longitudinal controllability and stability of OSR helicopter

In order to research the effect of rotor speed, blade spring stiffness and horizontal tail area on the controllability and stability of optimum speed rotor (OSR) helicopter, the flight dynamics model was established, and the induced velocity of rotor and aerodynamic interference of helicopter was calculated by free wake model. Finally the differential method was used to calculate the aerodynamic derivatives of the helicopter and control the derivatives matrix. The result shows that the controllability of the helicopter decreases with the decreasing of the rotor speed, but the change of stability about angle of attack was opposite. However the increase of blade spring stiffness in root can not only improve helicopter controllability, but also reduce the stability. The longitudinal stability of the OSR helicopter was decreasing without horizontal tail, and the handling qualities of sample helicopter are put at the third level in ADS-33E, but the period of instability oscillation cycle was longer, and the controllability of the helicopter was enhanced after cancelling horizontal tail. Thus, the scheme without horizontal tail for OSR helicopter is still controlled completely through the flight control system.