Numerical Modeling of Sub-Scale Convective Combustion of M1 propellant
Fumiya Togashi
1
, Rainald Lohner
2
, Joseph D. Baum
1
, Cynthia Romo
3
1
Applied Simulations Inc., 10001 Chartwell Manor Ct., Potomac, MD 20854
2
CFD Center, eorge Mason University, 4400 University Dr., Fairfax, VA 22030
3
Naval Air Warfare Center, Weapons Division, 130 Easy Rd., China Lake, CA 93555
Abstract
A numerical methodology capable of modeling HD 1.3 gun propellant combustion has been
developed. The model is based on observations of several tests conducted by NAWCWD which
included ignition of propellant pellets packed into cylindrical polycarbonate tubes. The
systematic sequence of tests clearly indicated the significant role pellet gasification plays in the
accidental ignition of propellants. To enable such modeling new algorithms to evaluate heat
transfer from the igniter combustion products to the gun propellant, pellet gasification, propellant
pyrolysis and combustion of the generated gasses and the propellant were implemented.
Development and validation of these models has been guided by the experimental NAWCWD
data.
Introduction
The Department of Defense Explosive Safety Board (DDESB) recently began revising the siting
methodologies for energetic ordnance other than Hazard Division (HD) 1.1. An investigation
indicated that improvements of the predictive modeling of HD 1.3 gun propellant (M1)
combustion placed in a confined storage configuration is necessary.
Funded by DDESB, the Naval Air Warfare Center Weapons Division (NAWCWD) has been
conducting a series of experiments of bulk HD 1.3 gun propellant combustion within a confined
polycarbonate tube in order to gather insight into the transient combustion behavior of a lightly
confined porous bed of HD 1.3 gun propellant.
To date, NAWCWD has conducted 3 calibration tests and 6 propellant combustion tests. The
calibration tests checked the igniter performance without the propellant bed. Figure 1 shows the
configuration of one of the combustion tests. A 5-3/4-inch inner diameter, 6-inch outer diameter
polycarbonate cylinder of 13 inches in length was used to house the M1 propellant bed. Figure 2
shows the M1 gun propellant, which had a density of 1.569 g/cc, the outer diameter of 1.0765,
the length of 0.5 cm. Each pellet had 7 perforations, each with a nominal diameter of 0.451mm.
Red Dot smokeless powder was used as an igniter, filled in a steel igniter basket hanging on the
top of the steel lid. Figure 3 shows the pressure history of the calibration test and propellant
combustion test, termed here test#1. In both calibration and combustion tests, 20g of Red Dot
was used as the igniter. The amount and height of the M1 propellant in test #1 was 7lb and 8.38
