Sensitivity Analysis for the Inductance Gradient of EMFY-3 Electromagnetic Launcher


Tosun N., Civil A., Oruc A. Y. , Yildirim B., Ozceylan B. M. , Bolat B., ...More

IEEE TRANSACTIONS ON PLASMA SCIENCE, vol.50, no.2, pp.381-386, 2022 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 50 Issue: 2
  • Publication Date: 2022
  • Doi Number: 10.1109/tps.2022.3140224
  • Title of Journal : IEEE TRANSACTIONS ON PLASMA SCIENCE
  • Page Numbers: pp.381-386
  • Keywords: Rails, Drag, Inductance, Mathematical models, Friction, Aerodynamics, Force, Electromagnetic launchers (EMLs), finite-element (FE) analysis, muzzle voltage, pulsed-power supply (PPS), railgun, transition, TRANSITION, MODEL, SIMULATION, TRANSIENT, VELOCITY

Abstract

ASELSAN Inc. has been working on electromagnetic launch technologies since 2014. The first prototype, EMFY-1, has a 25 mm x 25 mm square bore and 3-m-length rails. The second prototype, EMFY-2, has a 50 x 50 mm square bore and 3-m-length. This article presents a recently developed prototype, EMFY-3, with a 50 x 75 mm rectangular bore and 6-m length. The input energy of the pulsed-power supply (PPS) is doubled to 8 MJ, and the 2.91 MJ muzzle energy is obtained. Velocity curves are captured with Doppler radar, enabling us to establish propulsive inductance gradient $L<^>{'}_{{pr}}$ transients empirically. The results confirm that $L<^>{'}_{{pr}}$ is constant throughout the launch, as no significant breaking mechanism occurs with the non-magnetic containment. However, a slight variation (2% at maximum) happens with different rails' current magnitudes from one launch to another. The transition phenomenon is a candidate for the drop in the $L<^>{'}_{{pr}}$ , as it occurs more likely at launches with higher linear current densities. Moreover, a sensitivity analysis is conducted to show the importance of $L<^>{'}_{{pr}}$ calculations. A deviation of 5% from the actual value can cause an error in muzzle velocity up to 6.2%. This fact indicates that simulation models are very susceptible to $L<^>{'}_{{pr}}$ calculations. Although $L<^>{'}_{{pr}}$ is calculated as 0.515 mu H/m with 3-D finite element method (FEM), the Kerrisk formula calculates as if 0.561 mu H/m; the experimental measurement gives 0.575 mu H/m. These methods differ by 8% at maximum, which causes muzzle velocities errors. Regarding empirical findings, the 3-D FEM model calculates $L<^>{'}_{{pr}}$ more precisely than analytical formulas, and the contrast between models have grave importance due to the muzzle velocity errors.