Heat Generation and Thermal Management of a Rapid-Fire Electromagnetic Rail Launcher

Abstract

The pulse current can raise the bulk temperature of rails in the electromagnetic rail launcher (EMRL) during each shot. Quantifying the energy deposited in the rails and implementing an effective thermal management system are the key to tactical applications of the EMRL. This paper acquired the spatial distribution characteristics of total heat in the rails by using an analytical model and a multiphysics coupled model based on the hybrid finite-element/boundary-element method. The rail segment that produces the most heat is located where the armature arrives near the end time of the rising edge of pulse current. Since the rails suffer the severest stress when the armature passes, the key to the thermal management is to control their residual temperature rise when the armature passes. Therefore, the horseshoe cooling grooves dug on the back of the rails, which have low-stress concentration effect and good engineering feasibility avoiding internal drilling problem, are enough to effectively cool the rails. The experimental data measured by the fiber Bragg grating sensors in the tests of a single shot and a rapid firing of two agree well with the simulation results, which verifies the validity of the thermal management strategy. Furthermore, through prediction, the maximum residual temperature rise is only 2.57 K in the stage of heat balance at a sustained firing rate of 12 shots per minute for the 30 mm $\times30$ mm rectangular caliber launcher presented in this paper. These conclusions are also adaptive to large-scale launchers and have guiding significance to the engineering application of the EMRL.