Rational Corrections to R.W. Gurney’s Long-Bomb Analysis

English solid-state physicist Ronald Gurney did a somewhat unintentional wartime stint at Aberdeen Ballistic Proving Ground in Maryland, where he studied bomb-case stretching and fragmentation. There he derived a simple yet elegant case-expansion model, which is useful for simply estimating heat of detonation via the Cylinder Expansion (CylEx) test. Gurney made several simplifying assumptions, to which multiple explosives workers have applied (mostly empirical) corrections in order to improve accuracy. The most obvious and tractable neglected physical effects are 1) lateral flow and 2) tube strength. I previously presented physically-based corrections for both effects [1], but space limitations prevented me from providing derivations. Instead, I promised to provide them here, which I do. I find that, based on more accurate numerical simulations, Gurney-estimated heats of detonation are a few percent too small without the corrections, and are substantially correct with them.

1. Hill LG (2024) The TGH Method for CylEx Test Analysis, 17^th Symp. (Int.) on Detonation, Kansas City, KS