Research And Simulation Of An Electromagnetic Launcher For Forest Fire-Fighting

The situation of forest fire-fighting allowed of no optimist in China. Every year, the losses caused by combustions in forest are very huge. Electromagnetic launch is a fire method, through which the projectile body is shot by electromagnetic force generated by launcher. Fast primary speed, long range of fire, and easy control are its features. Base on the progress achieved in the field of electromagnetic launch and requirement of forest fire-fighting, a new type of fire fighting equipment, named Electromagnetic Launcher for Forest Fire Control, was studied in this paper.The architecture and launching mechanism of Electromagnetic Launcher for Forest Fire Control were expounded, the structure and control style of linear launching motor were emphasized. A mathematical modeling of air-gap magnetic field was established by means of analytic method, to study the air-gap magnetic field distribution inside the linear launching motor. The two-dimensional scalar magnetic potential of air-gap magnetic field was calculated by solving the Laplace equation, and then the analytical expression of the magnetic induction intensity of the air-gap was obtained. The magnetic induction intensity of the air-gap??the stator surface was calculated by utilizing analytical expression and finite element method, respectively, and found that the results obtained are almost the same, thus, the correctness of the analytical expression was confirmed. The impact caused by the duty cycle, thickness of magnetic pole and the changes of the length of air-gap on magnetic induction intensity of the air-gap was discussed by analytical methods. The results show that the magnetic induction intensity of air-gap increases with the increase of the thickness of permanent magnet until it become saturated gradually and decreases with the increase of the length of air-gap. The analysis of air-gap magnetic field offers the reference for the design of corresponding linear motor. Then, based on the energy equilibrium principle, the energy transfer process in the launcher was analyzed by means of analytic method. Next, based on the analysis of energy transfer process, the cogging force of the linear motor was analyzed, and the cogging force was effectively weakened.Numerical analysis of electromagnetic launcher was carried out by mean of FEM. The armature reaction was analyzed by FEM, The result shows that, with the increasing of poles' height, the effect of armature reaction to the poles are weakening, and so does as demagnetization. Then the dynamics of electromagnetic launcher, such as electromagnetic force, speed, were also analyzed by FEM. The results show that, the electromagnetic force increases with the current in stator coil until it become saturated gradually; The electromagnetic force also increases with the pairs of poles and the depth of poles. With the mutual affinity between the poles'magnets and stators, the stators are suffered very large lateral force, however, the structure of bilateral stators could balance the lateral force well. The results also reflect speed of moving part and time of a linear relation. Last, the fire range of launcher was analyzed. The results confirm the good dynamic property of the launcher.