The EFP Formation and Penetration Capability of Double-Layer Shaped Charge with Wave Shaper

Detonation waves will bypass a wave shaper and propagate in the form of a horn wave in shaped charge. Horn waves can reduce the incidence angle of a detonation wave on a liner surface and collide with each other at the charge axis to form overdriven detonation. Detection electronic components of small-caliber terminal sensitive projectile that are limited by space are often placed inside a wave shaper, which will cause the wave shaper to no longer be uniform and dense, and weaken the ability to adjust detonation waves. In this article, we design a double-layer shaped charge (DLSC) with a high-detonation-velocity explosive in the outer layer and low-detonation-velocity explosive in the inner layer. Numerical and experimental simulation are combined to compare and analyze the forming process and penetration performance of explosively formed projectile (EFP) in DLSC and ordinary shaped charge (OSC). The results show that, compared with OSC, DLSC can also adjust and optimize the shape of the detonation wave when the wave shaper performance is poor. DLSC can obtain long rod EFPs with a large length-diameter ratio, which greatly improves the penetration performance of EFP.

ON THE MECHANISM FOR MAINTAINING AN OVERDRIVEN DETONATION IN A ROTATING DETONATION ENGINE

At present, virtually all jet engines are based on the Brighton thermodynamic cycle (combustion at constant pressure). The improvement of such engines has already reached its technological limit. A significant increase in the efficiency of jet engines (by 20%-25%) can be provided by a transition to the Fickett-Jacobs[4] thermodynamic cycle which uses detonation combustion. One possible realization is a rotating detonation engine (RDE) in which the combustion chamber is the space between two coaxial cylinders. In an ideal scheme, a fuel mixture is supplied from one end which is ignited by a shock wave rotating in the annular gap with the Chapman-Jouguet velocity, i.e., with a speed equal to the speed of sound relative to the combustion products. It is known that in reality, a much more complex system of gas dynamic discontinuities is formed, consisting of triple configurations of shock waves. Detonation occurs only on the so-called Mach stems and not throughout the entire volume. In this paper, the possibility of creating a traveling overdriven wave by moving an obstacle behind the detonation area is investigated. Particular attention is paid to the initial stage - detonation initiation. A numerical method of the second order of accuracy with a finite rate of chemical reactions is used.

Investigation on the Time Error of Detonation Acoustic in Process of Formation and Propagation

The time error of detonation acoustic in process of detonation formation and propagation in a multi-cycle gas-liquid two-phase pulsed detonation engine is experimentally investigated. Results from the tests show that before the detonation wave escapes through the open-end of PDE tube, the maximum average arrival time error of detonation acoustic is achieved in the process of overdriven detonation. After detonation wave exists of PDE tube, arrival time error at 0 deg is greater than the other directivity angles in all distances and increases dramatically first and then almost stays at a certain value. The filling fraction has a major impact on the time error of detonation acoustic. With filling fraction increasing, there are increases in arrival time error and interval time error. Arrival time error with the highest filling fraction at 30 deg is much greater than other filling fraction. The convergent nozzle exhibits a marked suppression in the time error of detonation acoustic, where the maximum reductions of 62.02 percent and 56.13 percent are obtained in arrival time error and interval time error respectively.