| Compared with the traditional chemical energy emission technology,electromagnetic emission technology has the advantages of higher emission speed,more controlled launch process,using clean energy and so on.Among the existing guides rail type,coil type and reconnection type electromagnetic emission technology,the reconnection type launch technology starts the latest,but in principle it overcomes the problem of pivot rail ablation caused by guide rail type launch.The radial electromagnetic force of the coil launch is greater than the axial electromagnetic force.And the reconnection launch technology combines the advantages of the guide rail type to achieve high-speed linear emission and coil type to launch high-mass emitters,so the reconnection launch technology has higher application value and wider application fields.In order to obtain higher launch speed,the multi-stage launcher,as a research hotspot,occupies a large space and high production cost.Thus it is necessary to improve the launch efficiency in order to ensure a better comprehensive performance of the device.This paper takes the multi-stage reconnection launcher composed of box drive coil and plate armature with high mechanical strength as the research object.Firstly,the dynamic electromagnetic field model of the loading process of the multi-stage reconnection electromagnetic launcher and the dynamic equation considering the inter-stage coupling effect are established,which provides a theoretical basis for the efficiency optimization design.The above model is simulated and solved,and the calculation results show that the dynamic loading characteristic of the multi-stage reconnection launcher depends on the motion state of the armature.The higher the armature loading speed is,the stronger the weakening effect of the coupling magnetic field is.The smaller the peak value of the accelerating electromagnetic force on the armature is,and the forward position of the reverse electromagnetic force is.Thus it leads to the gradual decrease of the velocity increment of all levels and the emission efficiency of the device with the increase of the series.Secondly,through the structure optimization of the device,the emission efficiency of the single-stage launcher is improved,and the structure of double-wound drive coil is proposed.On the basis of the structure optimization of the single-stage launcher,the influence of the device parameters on the emission efficiency under different loading speeds is calculated,and the dynamic optimization strategy of the multi-stage device parameters is obtained by combining the trigger strategy of the multi-stage launcher.After optimization,the emission efficiency of the 100-stage device is increased from 4.3% to 17.65%.In addition,a magnetic field control method based on magnetic core is proposed in this paper.The number of magnetic lines truncated by the armature is increased by increasing the E-type magnetic core,so that the accelerated electromagnetic force on the armature is increased,thus the maximum emission efficiency of the device is improved.Finally,a multi-stage reconnection electromagnetic emission experimental platform is built in this paper.Firstly,the effects of trigger position,charging voltage and coil structure on the launch performance are verified,and the experimental results verify the reliability of the simulation method.Then an experimental study on the two-stage launcher with magnetic core is carried out to verify the effect of magnetic core on the improvement of emission efficiency.Then according to the efficiency optimization results,an eight-stage experimental device is designed and built.The armature and load of the total weight 12 kg are loaded into the 4m/s.The experimental results show that this study can provide a reference for the efficiency optimization of multi-stage reconnection electromagnetic launchers. |
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