Analysis of Rotation Speed Latching of Electromagnetic Launch Hypervelocity Projectile
Li Xiangping1, Lu Junyong1, Fan Pengfei2, Zhang Xiao1, Liu Yingquan1, Song Jinlong1
1. National Key Laboratory of Electromagnetic Energy Naval University of Engineering Wuhan 430033 China; 2. School of Astronautics Northwestern Polytechnical University Xi'an 710072 China
Abstract：The problem of rotational speed lock often occurs in the flight process of the projectile body with asymmetrical pneumatics. Due to rotational speed lock, a large equilibrium nutation angle will be generated, resulting in increased flight resistance of the projectile body, destruction of the dynamic stability characteristics of the projectile body, and catastrophic yaw will occur in severe cases. However, the electromagnetic (EM) launching projectile is more prone to rotational speed lock due to the impact of its launching principle and launching environment. Aiming at the speed lock phenomenon caused by exit disturbance and aerodynamic asymmetry, this paper studies the speed lock principle, speed lock modeling and speed lock boundary analysis, in order to reveal the principle of speed lock and lay a theoretical foundation for its speed lock design and control. Firstly, based on the principle of speed lock and the six-degree-of-freedom (SDOF) kinematic theory, a SDOF speed lock model considering the asymmetric angle of attack, sideslip angle and zero deflection angle of rolling channel is established. Secondly, based on the data of a live firing test, NSGA-Ⅱ genetic algorithm is used to identify the initial disturbance and non-weighing of the projectile, and the rotational speed locking phenomenon of an EM projectile is simulated and verified the correctness of the rotational speed locking model established in this paper. Finally, based on the identified speed lock influence conditions, the speed lock safety zone of the projectile is analyzed, and the speed lock distribution under different initial disturbance angular velocity and asymmetric angle is given. The simulation and test results show that: (1) The speed locking model established in this paper can reveal the speed locking characteristics of the EM launching ultra-high speed projectile, and the simulation results are in agreement with the test results. (2) The larger the initial disturbance angular velocity of the projectile, the less likely it is to produce speed lock. This is because under certain aerodynamic asymmetry, the larger the initial disturbance, the greater the roll speed induced by the projectile, and the greater the difference between the roll frequency and the pitch and yaw motion frequency, so as to avoid speed lock. (3) There is a value corresponding to the pitch and yaw motion frequency of the projectile, which is ±0.2°. When the asymmetric rolling rudder control angle is closer to this value, the speed lock is more likely to occur; when it is far away from this Angle, the speed lock is not easy to occur. In this paper, a speed lock modeling method combining equivalent asymmetric moment method and multi-variable and multi-objective genetic algorithm is proposed, which can reproduce the speed lock phenomenon well. However, there is little analysis on the influence mechanism of non-symmetrical weighing on speed lock. Meanwhile, only the safety boundary analysis of speed lock is given, and the control strategy of speed lock is not studied. In the following, the influence mechanism of non-opposite weighing on speed lock is further studied from the kinematic and dynamic equations of projectile, and the control strategy and control effect analysis of speed lock are given.
李湘平, 鲁军勇, 樊朋飞, 张晓, 柳应全, 宋金龙. 电磁发射超高速弹丸转速闭锁分析[J]. 电工技术学报, 2024, 39(19): 5929-5936.
Li Xiangping, Lu Junyong, Fan Pengfei, Zhang Xiao, Liu Yingquan, Song Jinlong. Analysis of Rotation Speed Latching of Electromagnetic Launch Hypervelocity Projectile. Transactions of China Electrotechnical Society, 2024, 39(19): 5929-5936.
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2024, Vol. 39 
