Progress Toward a Multidimensional Representation of the 5.56-mm Interior Ballistics

Report No. ARL-TR-4903
Authors: John R. Schmidt; Michael J. Nusca
Date/Pages: August 2009; 34 pages
Abstract: There is significant experimental evidence that burning particles of various chemical compositions and sizes are ejected from gun primers and that these particles interact with the propellant grains during main charge ignition. This explicit ignition phenomenon is thought to be incompatible with the implicit treatment of primer function used in conventional interior ballistics codes and models. Generally, the primer efflux is treated as a hot gas that evolves from a specified region in the model's representation of the gun chamber. Essentially, an igniter table is derived from experimental means and by careful calibration of the interior ballistics simulation using gun firing data. With the advent of multidimensional, multiphase interior ballistics codes that employ coupled Eulerian-Lagrangian schemes to explicitly treat both the gas and solid phase, a primer model that is commensurate with the availability of such an interior ballistics model is developed. A further development in the formulation of a primer model that is compatible with the ARL-NGEN3 code and small-caliber weapons is described herein. The model is based on the One-Dimensional Turbulence modeling approach. Integration of the primer model with the ARL-NGEN3 code is shown. Preliminary simulated results comparing primers with particles and primers without particles provide key insights into the early initiation phase of small-caliber ammunition.
Distribution: Approved for public release
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Last Update / Reviewed: August 1, 2009