Influence of the clearance between initiating unit and main high explosive charge on jet perforator efficiency

Abstract

Influence of the clearance between initiating unit and main high explosive charge on penetration depth of a jet perforator at low ambient temperatures is investigated. Experiments were conducted on jet perforators, which consisted of an initiating unit (including detonator and an intermediate high explosive charge enclosed in a thin metal cylindrical shell) and a main high explosive charge with metal-lined cavity. External diameter of the perforator was 42 mm. We observed significant decrease (up to 50%) of penetration depth at low ambient temperatures. It has been observed during the experiments that the effect of the decrease of penetration depth at low negative temperature was absent, when a small clearance existed between the initiating unit and the main high explosive charge. Thus, it has been determined that a clearance between the initiating unit and the main high explosive charge can be used to improve the perfection of detonation front. The problem of parameter optimization for the transition zone between the initiating unit and the main charge was studied using the methods of numerical modeling provided by ODVAX software. Numerical and theoretical analysis of the detonation initiation process for various values of the initiating unit wall thickness (0.5, 1.0, 2.0 mm), and for different materials for its shell has revealed that maximum reduction of the acceleration stage, after which the detonation reaches stationary mode, is achieved when: – Thickness of the initiating unit wall facing the high explosive charge equals to the permissible minimum for required mechanical properties. – Clearance width equals to 2–3 times the wall thickness. – Shapes of the main charge and the initiating unit wall are congruent at the moment of collision.