Mortar Interior Ballistics: Sensitivity Studies Using IBHVG2 and Progress Toward a Multidimensional Representation

Report No. ARL-TR-4838
Authors: John R. Schmidt; Michael J. Nusca; Albert W. Horst
Date/Pages: June 2009; 38 pages
Abstract: Traditionally, the interior ballistic (IB) modeling of mortars has been difficult to achieve because a mortar projectile contains certain energetic components internal to the tail boom. After ignition, high pressure generated by the igniter causes the canister to burst and release hot gases and burning particles into the larger chamber called the launch tube. Subsequently, any external charges ignite and produce gases which accelerate the projectile. A recent advancement to the IBHVG2 code allows the modeling of this high-low (HILO) configuration. This HILO feature comes with the introduction of two new parameters into the IBHVG2 model, essentially gas-phase and solid-phase discharge coefficients governing flow between the two chambers. The large-caliber gun community focuses on the impact of seven IB input variables (charge weight, force, propellant diameter, burning rate coefficient and exponent, covolume, and projectile weight) on the peak chamber pressure and projectile exit velocity. A sensitivity study on these input variables was performed on the high and low canister over a small range of the nominal value. The HILO feature was also examined for a 120-mm mortar. Uncertainty associated with the two new free parameters necessitated a wider range of investigation of said parameters.
Distribution: Approved for public release
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Last Update / Reviewed: June 1, 2009