Modeling Ignition and Flamespread Phenomena in Bagged Artillery Charges
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
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One-dimensional, two-phase flow, interior ballistics codes, successfully applied on numerous occasions to cased-ammunition problems, have proven to be less satisfactory in simulating flamespread and pressurization profiles in bagged propelling charges. Configural complexities associated with the chargechamber interface, as well as ill-characterized impedances to gas and solid-phase flows offered by the bag and other parasitic components, rendered treatment of most artillery charges outside the scope of existing models. Simulations of the US 155-mm, M198 Howitzer firing the Zone 8S, M203 Propelling Charge, obtained using the one-dimensional NOVA code, clarify this problem. Solutions are then presented which are based on a quasi-two-dimensional code in which the charge and the unoccupied portion of the gun chamber are represented as disjoint but coupled regions of one-dimensional flow. Early-time gas flow external to the bag is shown to alter the flame path and equilibrate pressures throughout the chamber however, this process reflects both the extent and persistence of the ullage, which are seen to be direct consequences of bag dimensions and material characteristics. The impact of these processes on a current effort to develop a fully two-dimensional NOVA code is discussed, and the status of this 2-D code with respect to the bagged-charge problem is outlined.
- Computer Programming and Software
- Ammunition and Explosives
- Combustion and Ignition