An Experimental and Modeling Study of Ingredients for Propellant Burn-Rate Enhancement
ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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Novel propellant formulations are critical for developing Future Force gun and missile systems that are safer, smaller, and more lethal than those used presently. We employ our US Army Research Laboratory combustion model, CYCLOPS, to predict the burning rates of nitrocellulose with and without HN3, a stable pyrolysis product of high-nitrogen compound 5-aminotetrazole 5-AT. Our model employs a detailed chemical kinetic mechanism containing 368 chemical reactions and 59 species. We test its HN3 chemistry by studying both neat and HN3-doped flames experimentally and with the PREMIX flame code. We measure the major and radical species concentrations by either molecular beam mass spectrometry, laser spectroscopy, or both, and compare them to those we model with PREMIX using the detailed chemical mechanism. The model predicts well the concentration of the postflame species, including the OH concentration, which decreases by about 12 with the addition of 1.1 HN3. However, the model does not predict adequately the shapes of the HN3 and NH profiles near the burner surface. Our rate and sensitivity analyses reveal that the rate expressions of reactions HN3OHN3H2O and HN3NHNH2N3 should be lower by a factor of 3 and 4, respectively, than what is reported in the literature. Our CYCLOPS calculations with mechanism updates show that the addition of HN3 to nitrocellulose enhances its burning rate significantly over the 10 to 300-MPa pressure range a factor of approximately five at 10 MPa.
- Physical Chemistry
- Combustion and Ignition
- Rocket Propellants