Effects of Perforation L/D Ratio and Slotting on Stick Propellant Combustion
Final technical rept. 1981-1983
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
Pagination or Media Count:
Closed bomb combustion studies were performed on single-perforated 1P and slotted 1P NOSOL 363 propellant samples ranging in length from 19 to 338 mm. Samples having equal webs, but differing in their perforation diameters as well as lengths were examined. Samples with larger perforation diameters PD 2.13 showed an increase of observed burning rate with length. For example, at 200 MPa, the burning rate of the 338 mm samples was 17 percent greater than the burning rate of the 19 mm long samples. In the case of the samples with smaller 0.940 mm perforation diameter, however, the fastest burning rates were observed for the medium length 168 mm rather than the longest samples. All slotted and short granular propellant samples, irrespective of perforation diameter, exhibited essentially identical burning rate characteristics. The studies indicate that, at least under closed bomb conditions, slotted 1P stick propellants burn just like granular propellants. In the case of unslotted 1P stick propellants, however, complex burning augmentation effects exist. Some of the mechanisms may involve increases in the burning rate inside the perforations due to enhanced pressure andor erosive burning effects as well as grain splitting. Modeling propellant burning via the grain splitting and pressure build up hypotheses was partially successful in accounting for the observed effects.
- Ammunition and Explosives
- Combustion and Ignition