Analysis of Circular Chamber Armatures With Different Initial Winding Angles

Conventional electromagnetic rail launch projectiles are tail stabilization method for high-precision launching, but for the small caliber electromagnetic rail launching systems, the tail stabilization method is not feasible due to the bore size, so the circular chamber anti-symmetric enhanced electromagnetic launch structure is proposed. It can provide rotational torque and electromagnetic thrust for the circular armature to achieve high initial velocity and spin stability of the circular armature. At present, the circular armature adopts multitail straight slit structure, and the armature suffers from tail breakage and rotational instability after exiting the chamber, mainly because of the alternating positive and negative rotational torque of the armature during the electromagnetic launch process, which seriously affects the flight attitude and stability of the armature. Aiming at the problems in the existing armature firing process, an initial winding angle-type armature structure is proposed based on the 18-mm inner chamber structure, and the structural relationship between the initial winding angle
$\theta $
and the tail length
$L$
and the number of narrow slits
$N$
is studied, the effect of different initial winding angles (
$\theta $
= 48.5°, 29.5°, 20.6°, and 15.8°) on the electromagnetic thrust, torque, and electromagnetic field was compared and analyzed, and it was concluded that: the initial winding angle has a small effect on the magnitude of electromagnetic thrust of the armature; the larger the initial winding angle and the smaller the number of open slits, the less the thrust cycle variation; the initial winding angle has a larger effect on the torque, the smaller the initial winding angle, the more the cycle variation, the larger the armature torque, and when
$\theta \le29.5^{\circ }$
, the armature torque without reverse phenomenon appears; with the decrease of initial winding angle, the maximum current density of armature is concentrated from the edge of armature tail to the root of armature tail. Combined with the analysis results, the armature with initial winding angle
$\theta $
= 29.5° is chosen for the 18-mm bore structure, which can ensure the structural strength of the armature and provide a continuous unidirectional torque. The proposed initial winding angle typed armature provides an effective solution to the armature bore torque reversal, which is conducive to improve the firing stability of the armature.