Approximate Field Scaling of Railgun Launcher Under the Condition of Matching Projectile Dynamic Parameters

The results and experiences gained from the subscale railgun launcher's test can be extremely valuable to succeed with the full-scale railgun. This paper proposes an approximate field scaling method of the electromagnetic railgun launcher under the conditions of matching projectile dynamic parameters. A detailed derivation and numerical validation are presented in this paper. According to the results of the analytical derivation, the magnetic and temperature fields between two scales of railgun launchers can be matched if the time scaling factor is equal to the square of the geometric scaling factor in the rail thickness direction and if the linear current density remains equal between two scales. However, the stress field cannot be matched as long as the scaling method is desirous of using the same material in two scales and to match the magnetic and temperature fields as well. Numerical simulations are then conducted to assess the scaling performance. Simulation results show that profiles of projectile velocity are identical in two scales under the specific conditions. The magnetic and temperature fields can be matched well, but they are not exact images, which means that the field scaling method is an approximate scaling method. The stress field in the simulation cannot be matched between subscale and full scales, which validates the analytical derivation results. The results can be used to provide guidance for the suitable subscale tests of electromagnetic railgun.