Ignition and combustion of boron particles at one to ten standard atmosphere

The ignition and combustion of boron particles are investigated at high pressures in the range of 1-10 atm. Observation results show that the combustion of 2 μm amorphous boron particles occurs in two continuous stages. The combustion times of boron particles are measured. The first stage combustion time decreases slightly with an increase of pressure, whereas the second stage combustion time shows strong dependence on pressure. Measured first stage combustion times are compared with the predictions of two typical numerical models, the King model and the Yeh and Kuo model. Both models overpredict the experimental data at higher pressures. The governing equations of the two models have been analyzed to reveal the reasons for the inaccuracy of the predictions. A new model has been developed on the basis of the Yeh and Kuo model, by introducing B(s) = 3/4O₂(g) → 1/2B₂O₃(l) as the global reaction of B and O₂. The prediction of the new model is in good agreement with experimental results, especially under high-pressure conditions. This study can bridge the gap between atmospheric pressure data and the higher-pressure data of previous work.