Numerical Model Solution and Analysis of Effect Factors of Boron Ignition and Combustion Behaviors

The ignition and combustion kinetic model for single boron particles in oxygenated environment containing O₂ and H₂O was developed. The specific numerical solution method was introduced. Prediction of the models was in good agreement with experimental data. The effects of particle size, initial oxide thickness, ambient pressure, partial pressure of oxygen, partial pressure of water vapor, and ambient temperature on boron ignition and combustion were investigated by numerical calculation. The results were compared with experiment as well. The results show both the ignition and combustion time increase with increasing particle size. The combustion time is found to be in direct proportion to particle size, but this dependency changes to quadratic when the particle size exceeds 20μm. The ignition time increases significantly as the initial oxide layer increases with a growth rate of 65ms/μm. Increased ambient pressure reduces both the ignition and combustion time, whereas the sensitivity is very weak at pressure higher than 3MPa. The ignition time is independent of oxygen partial pressure but decreases with increased water vapor partial pressure. On the contrary, the combustion time is independent of water vapor partial pressure but decreases with increased oxygen partial pressure. Similar effects on the ignition and combustion time as function of ambient temperature are obtained.