Detonation Wave Front Curvature of a Nonideal Explosive

The detonation characteristics of nonideal explosives are of particular interest due to their atypical sensitivity, corner turning capability, and shock to detonation transition when compared to more comprehensively understood ideal formulations. Ideal explosive formulations typically become steady over short distances (< 1 inch) and exhibit planar denotation fronts with small (< 1mm) reaction zone widths. This lends to their excellent corner turning ability. Conversely, detonations in nonideal explosives require significant distances to become steady while transitioning from highly concave to near-planar wave front shapes and exhibit large reaction zone widths. These combined characteristics lead nonideal explosives to exhibit poor corner turning ability and potential for dead zones. A study of detonation wave front curvature and curvature growth was performed on a nonideal aluminized explosive formulation. Detonation velocity and Chapman-Jouguet (CJ) pressures were also measured using Photon Doppler Velocimetry (PDV). Tests were conducted using oxygen free OFHC copper tubes with outer diameters (OD) of 2.4 and 4.8 inches. Cast pentolite boosters with an OD of 2.0 inches were used for both test article sizes. Pentolite boosters with an OD of 4.0 inches were also used with the 4.8-inch OD test articles. Output wave curvatures were obtained using streak imaging at 4, 7, 10, and 19.5 inches from onset for all previously described geometries and booster sizes. The results of this effort demonstrate the long distances to achieve steady detonation, which are on the order of several to tens of inches, for nonideal explosives. This effect is especially true in cases where boosters are undersized with respect to main fill diameters. The data collected provides insight into the formulation’s potential dead zones resulting from its corner turning ability, distances to steady detonation, and reaction zone characteristics.

Keywords. Nonideal Explosives, Detonation Curvature, Detonation Velocity