APPLICATION OF GURNEY AND FLIGHT OF FRAGMENT CALCULATIONS FOR WATER JET VELOCITIES IN EXPLOSIVE APPLICATIONS

This study examines the use of Gurney equations, typically applied to metal fragment velocities, in modeling water jet behavior in percussion actuated non-electric (PAN) disruptors, tools for improvised explosive device neutralization. Experimental tests used three charge strengths (2.59, 5.83, and 7.13 grams) and two configurations: standard (full-barrel water load) and “negative 8” (partial water load). High-speed footage captured water column velocities, which were compared to predictions from infinitely tamped and open-faced Gurney models and flight of fragment calculations. Results showed that higher charge strengths increased velocity and stability, with the model closely predicting velocities, deviating by as little as 1.4% for standard charges and 2.8% for negative 8 charges. Flight-offragment predictions were most reliable at distances of 0.46 m for standard charges and between 0.61 and 0.91 m for Negative 8 charges. These findings improve understanding of Gurney model applications to fluids.