Effect of silane addition on acetylene ignition behind reflected shock waves

Ignition delay time and species profile measurements are reported for the combustion of C2H2/O2/Ar mixtures with and without the addition of silane for temperatures between 1040 and 2320 K and pressures near 1 atm. Characteristic times, namely ignition time and time to peak, were determined from the time histories of CH* (A2Δ → X2Π) and OH* (A2Σ+ → X2Π) emission near 430 and 307 nm, respectively. For the cases without silane, there is good agreement between the present data and some recent acetylene oxidation results. Small SiH4 additions (<10% of the fuel) reduced the ignition time in stoichiometric mixtures by as much as 75% for shocks near 1800 K. Similar reductions were seen in the fuel-lean mixture, although the effect was less temperature dependent. Several detailed chemical kinetics mechanisms of hydrocarbon oxidation were compared to the ignition delay-time data and species profiles for C2H2/O2/Ar mixtures without silane. All models under-predicted ignition time for the 98% diluted stoichiometric mixture but matched the fuel-lean ignition data somewhat better. Two of the models displayed the shift in activation energy at lower temperatures seen in the data, although no one model was able to reproduce all ignition times over the entire range of mixtures and conditions.