When armature passes through the central plane of a driving coil in the process of reluctance coil launching, the magnetic force will reverse and slow down the armature speed. To overcome this problem, the principle of reluctance coil launcher is analyzed. Meanwhile, this paper establishes a finite element analysis model to calculate the electromagnetic force, velocity, displacement and other parameters of the armature while the reluctance coil launcher works. Based on the simulation results, dynamic characteristics of the reluctance coil launcher are summarized and two methods for reverse force suppression are discussed. Furthermore, an experiment system is established and some experiments are carried out. This research concludes that resistor consumption method can effectively restrain the generation of reverse force, with no obvious bad impact on other performance, which provides a practical approach to achieving higher speed and efficiency for reluctance electromagnetic launcher.
Integrated methods are used in the modification of trajectory, including improved perturbation impact point deviation prediction, adaptive proportional guidance and adaptive proportional differential guidance, thus improving the firing accuracy of guided mortar shell. The six degrees of freedom of both the trajectory model and the control model were established, and their guidance laws were designed based on the three guidance schemes. Firstly, the perturbation impact point deviation prediction method is improved by setting up a discrimination factor in the rising phase of trajectory based on the principle of traditional perturbation impact point deviation prediction method and in combination with the trajectory characteristics of guided mortar, which further improves the correction efficiency. The adaptive proportional guidance law is designed in the longitudinal plane, while the adaptive proportional differential guidance law is designed in the transverse plane due to the fact that the constant proportional coefficient in the proportional guidance law does not conform to the requirements of actual trajectory. In this paper, Monte Carlo simulation method and ammunition flight test are used to verify the designed guidance law, and the simulation results illustrate that the integrated guidance method is both reasonable and effective. As for the error of the guidance tool and actuator, the method is available for the reduction of impact point deviation and the improvement of accuracy. The circular error probability (CEP) not under control decreases from 126.317m to 10.1284m when control is applied. Besides, the feasibility of the designed guidance law is verified by the flight tests of guided mortar projectile in large, medium and small range respectively from the perspective of engineering application. It can be seen from the test trajectory impact point data that the guidance law is available for the effective correction of trajectory deviation in the actual hardware operation and site environment with reliable guidance. As the outcome, the CEP reaches 10.86m, and the impact point deviation of some guided missiles is within 2m.
This paper concerns a new method for projectile disposal by emptying the explosives in projectiles with electromagnetic heating. It explains the basic principles of the emptying technology via electromagnetic heating. A multiphysical analysis model coupled with an electromagnetic, thermal, fluid and phase transition model is established, and the explosive melting simulation is conducted based on this model. The dynamic phase transition process of the explosive from solid to liquid is simulated, and the electric field, magnetic field and thermal field distribution characteristics during the process are analyzed. Furthermore, the effect of excitation current characteristics on the phase transition of the explosive is given, which shows that the explosive melting process is controllable by setting the excitation current amplitude or frequency. This paper provides a new method for the disposal of end-of-life projectiles, which is more controllable, safe and environmentally friendly.
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