空气升力对被动式半捷联平台稳定性影响分析

安装在高速滚转的常规炮弹上的被动式半捷联平台是基于重力作用下的复摆运动原理工作的装置。由于弹体在飞行时受到空气升力的作用，所以空气升力的变化会导致弹体在竖直方向上的加速度变化，而弹体在竖直方向的加速度变化会导致被动式半捷联平台的等效复摆回复力矩发生变化并影响平台的稳定性。为了研究空气升力对被动式半捷联平台稳定性的影响，对弹体和弹体内的被动式半捷联平台内筒进行了力学分析，建立了空气升力作用下的平台内筒的运动微分方程。通过对运动微分方程进行计算仿真，得到了不同空气升力作用时被动式半捷联平台内筒的滚转角度曲线和角速率曲线，并得到了平台保持稳定时空气升力所需满足的范围。仿真结果表明，弹体受到的空气升力越大，被动式半捷联平台的稳定性越高。当空气升力小于0.005 75 m_pg(m_p为弹体质量，g为重力加速度)时，被动式半捷联平台将失去稳定作用。在三轴高速转台上进行空气升力和重力相等时的被动式半捷联平台内筒运动状态的地面实验，实验结果验证了仿真结果的正确性。

Influence of Air Lift on the Stability of Passive Partial Strapdown Platform

The passive partial strapdown platform which installs in rolling projectile works in the principle of compound pendulum movement under the action of gravity. Projectile flies under the action of air lift, consequently the acceleration in the vertical direction of projectile changes with the change in the lift. Accordingly the restoring torque of the platform cylinder’s equivalent compound pendulum changes, and the stability of the platform would be affected. To research the influence of air lift on the stability of passive partial strapdown platform, the mechanical analyses of the projectile and passive partial strapdown platform cylinder are fulfilled, and the differential equation of motion of the platform’s inner cylinder is established and solved. The stability of passive partial strapdown platform under the action of air lift is simulated. The results show that the larger the air lift is, the more stable the partial strapdown platform is. And when the air lift is less than 0.005 75m_pg (m_p is weight of projectile, and g is acceleration of gravity), the passive partial strapdown platform is unstable. The semi-physical simulation test is done in the three-axis high speed turntable. The dynamic model is proved by the test.