The formation of jets from shaped charges in the presence of asymmetry

Abstract

The jet from a nominally axisymmetric shaped charge is formed by the collapse of the typically conical liner under the high pressures resulting from detonation of the explosive around it. Where asymmetries are present the velocities imparted to the elements of the liner at a given axial distance from the cone tip will vary as a function of the azimuthal angle among other variables. In general these elements will not meet at all. Conversely a pair of liner elements that do meet will in general have started from different axial positions, and will meet away from the nominal axis of symmetry of the charge. This effect renders the formation process asymmetrical. Consequently the jet particles have an off-axis velocity component which can substantially degrade the penetrative capability of the charge. A complete analysis of asymmetrical liner collapse and jet formation is presented for the case where the liner is axisymmetric, but there is an azimuthal variation in liner projection velocity. The classical analysis of symmetric liner collapse and jet formation is extended to include this type of asymmetry. Earlier work on linear shaped charges, particularly a model for asymmetric jet formation, is drawn upon to consider plane sections of the liner individually. A fully three-dimensional analysis is then achieved by the combination of the results for these sections. This analysis is implemented in a computational model and example results are presented and compared in as far as is possible and meaningful with previous theoretical and experimental results. Good agreement with the previous theoretical work is obtained, and the values of the off-axis velocity components predicted are of the orders observed in the limited experimental data as yet available.

Indirect-Drive Inertial Confinement Fusion Using Highly Supersonic, Radiatively Cooled, Plasma Slugs

“…Figure 2 shows a series of mass density contours from a simulation of a conical liner (8 ± angle, 1 mm thick, 80 mg͞cm) imploded by the MAGPIE generator, using 100 mm resolution. In this case, jet formation is analogous to that obtained with conical shaped charges [11]. The conical angle is set so that the traveling wave of the zippered implosion falls just behind the traveling head of the jet.…”

Research on the Formation Characteristics of the Shaped Charge Jet from the Shaped Charge with a Trapezoid Cross-Section

“…Considering the law of the conservation of momentum [ 18 ], the axial and the radial velocities of the SCJ and the slug from the annular liner element can be derived as follows: …”

Study on the effect of off-axis initiation on the jet forming process and armour-breaking performance of shaped charges

“…Most of the relevant research work have used off-axis velocities as an evaluation index to qualitatively describe the influence of off-axis initiation on the jet performance [3]- [5], while the correlation between asymmetric jet and armor-breaking performance has not been established. There are few public reports on a credible manufacturing tolerance of initiation offset to meet the requirement of warhead power.…”