STUDY OF SINGLET DELTA OXYGEN O2(1Δg) IMPACT ON H2-O2 MIXTURE IGNITION IN FLOW REACTOR: 2D MODELING

Influence of electron excited singlet delta oxygen (SDO) molecules produced in direct current (DC) glow discharged plasma on the induction length decrease in the H-2-O-2 mixture has been studied via comprehensive two-dimensional (2D) numerical simulations. The sensitivity analysis of the induction length on SDO mole fractions and residual mole fractions of odd oxygen was carried out. The influence of the reaction H-2 + O-2((1)Delta(g)) -> H + HO2 on the ignition length was found to be negligible due to the presence of residual odd oxygen in the oxidizer flow. Two stages specify the ignition time decrease for the studied conditions: (1) chain initiation in reactions with residual odd oxygen and (2) the following chain-branching enhancement due to reaction H + O-2((1)Delta(g)) -> O + OH. The last reaction is the key process for studied conditions when the concentration of SDO exceeds 4%. The estimated rate constant of this reaction was found to be about 2.5 . 10(-13) cm(3)/s at 780 K. The quenching reaction H + O-2((1)Delta(g)) -> H + O-2 does not affect the ignition length.