Continued Study of Stick Propellant Combustion Processes.
Memorandum rept. Oct 81-Sep 82,
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
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The interior ballistic performance of propelling charges employing perforated, unslotted stick propellant often cannot be simulated using either lumped-parameter or two-phase-flow models, the experimental maximum pressure being much higher than calculated. A continuation of studies, initiated in FY81, into this anomalous performance has provided experimental evidence that the major contributor to this increase in pressure is splitting of the propellant sticks, a consequence of higher local pressures inside the long perforations of the unslotted sticks. Second-order effects include erosive burning or coning at the ends of the perforations and augmented burning rates on the progressive interior surfaces caused by the locally increased pressure. Other observations slotted stick propellant was not found to split inside the gun, though fracturing occurred as the long grains tried to follow gas streamlines upon exiting a short-barreled test fixture short, unslotted stick propellant, like slotted stick propellant, did not split during the interior ballistic event, yet produced greater muzzle velocities than predicted and, finally, the NOVA two-phase-flow interior ballistic code provided good simulations of flamespread and pressurization inside the perforation of long, unslotted stick propellant.
- Ammunition and Explosives