Study on flame evolution and kinetics mechanism of H2-Air mixture with C3H9O3P-H2O fog addition

Abstract

Understanding the hydrogen explosion characteristics with inhibitors addition is indispensable for ensuring the safe application of hydrogen fuels. Influences of C₃H₉O₃P-H₂O fog addition on flame evolution and kinetics mechanism of hydrogen-air explosions is investigated with 3.4 L rectangular chamber and reaction kinetics model. The results demonstrate that the C₃H₉O₃P-H₂O fog promotes thermal-diffusion instability of the flame, resulting in the formation of cellular structures on the flame front. And the fog suppresses the formation of tulip flames and form a corrugated flame. Additionally, as the equivalence ratio increases, the attenuation effect of the C₃H₉O₃P-H₂O fog on explosion overpressure gradually decreases. The order of effectiveness in explosion overpressure reduction with fog addition position is P3 > P2 > P1. The influence of the C₃H₉O₃P-H₂O fog on hydrogen explosion overpressure is a coupled effect, involving both the expansion of flame surface area (Enhancement factor F_e∈ (1, +∞)) and the reduction of laminar burning velocity (Inhibition factor F_i∈ (0, 0.24)). From chemical kinetics perspective, C₃H₉O₃P-H₂O fog reacted and significantly consumed H, O, and OH radicals, with the consumption rate of radicals reaching at least 83 %. The main phosphorus-containing radicals, PO₂, HOPO, and HOPO₂, contributed to radical consumption through chain termination reactions (R12 ∼ R18), continuously consuming H, O, and OH radicals by forming stable compounds such as H₂O and H₂.