考虑空间机动飞行的直升机尾传动轴建模与临界转速分析

建立了具有普遍性的考虑直升机空间机动飞行的尾传动轴动力学模型.分析了机动飞行对尾传动轴临界转速的影响,发现只有俯仰角速度、偏航角速度、横滚角速度和角加速度4个转动运动分量会影响尾传动轴的临界转速.通过算例着重分析了俯仰、偏航和横滚角速度对尾传动轴前3阶临界转速的影响规律.结果表明:俯仰角速度使尾传动轴的临界转速降低,但只对反进动第1阶临界转速有较大影响;偏航角速度对尾传动轴临界转速的影响效果与俯仰角速度完全相同;正向横滚角速度使尾传动轴的正进动临界转速提高,而使反进动临界转速降低;但对于反向横滚,在以横滚角速度等于某值的分界线之前,横滚角速度对尾传动轴临界转速的影响规律与正向横滚相反,前3阶临界转速变化曲线的分界线对应的横滚角速度分别为1.86,27.41,124.5rad/s.

Modeling and analysis of critical speed for tail drive shaft of helicopter considering space maneuvering flight

The universal dynamical model of tail drive shaft of helicopter considering maneuvering flight was established. The reasons for maneuvering flight affecting the critical speed of tail drive shaft of helicopter were analyzed. It is pointed out that only a portion of the rotational motion components can affect the critical speed of tail drive shaft, including: pitching angular velocity, yawing angular velocity, rolling angular velocity and angular acceleration. The influence law of the pitching angular velocity, yawing angular velocity and rolling angular velocity on the first three order critical speeds of drive shaft was discussed through a numerical example. The results reveal that the pitching angular velocity reduces the critical speeds of tail drive shaft, but only has a greater impact on the first order critical speed of tail drive shaft in a backward whirl, and the yawing angular velocity has the same influence. The positive rolling angular velocity increases the critical speed of tail drive shaft in a forward whirl, and reduces the critical speed of tail drive shaft in a backward whirl; but in the case of negative roll maneuver, there is a reverse case compared with the positive roll maneuver that the backward rolling angular velocity reduces the critical speeds of tail drive shaft in a forward whirl and increases the critical speeds of shaft in a backward whirl, before the boundary of the rolling angular velocity equals to a special value. The rolling angular velocities corresponding to the boundary of variation curve of the first, second and third critical speeds are respectively 1.86, 27.41 and 124.5rad/s.