Liquid jets produced by an immersed electrical explosion in round tubes

Abstract

Liquid jets produced by an electrical explosion in water in round, centimeter-wide tubes are investigated experimentally and theoretically. Several jet flow patterns including sharp conical forms and annular forms are observed through high-speed photography. The general features of these patterns are presented and examined herein. It is found that the jet pattern is influenced mainly by the tube diameter, with narrow tubes producing conical jets and wide tubes producing annular jets. The jet maintains a nearly constant velocity, which increases with the explosion energy and decreases with the tube diameter and the standoff distance. A quasi-one-dimensional theoretical model that includes the bubble dynamics is proposed. With the model proposed herein, the effective explosion energy is calibrated first by matching the maximum bubble size. The results show that the confinement imposed by the tube tends to reduce the effective energy and that tubes with smaller diameters collect less effective energy. A theoretical analysis of the jet velocity indicates that the jet has to overcome a threshold energy level to obtain a constant velocity and that in narrower tubes, the jet velocity is amplified. The amplification factor, which is defined as the ratio of the actual jet velocity to the theoretical maximum bulk velocity, generally decreases with the tube diameter. It approaches unity when the jet is annular or blunt, indicating that the kinematic focusing effect with this type of jet is negligible. A parametric analysis of the calibrated explosion energy and the amplification factor provides a relation that comprehensively represents the experimental data. The relation is found to be different from those obtained in previous investigations, and the reasons for this difference are discussed.