Shock Tube Study of the Induction Lag in Nitrous Oxide‐Hydrogen System

Induction lags behind incident shock waves have been measured in nitrous oxidehydrogen mixtures diluted with 90 or 95% of argon. The physical magnitudes detected in order to characterize the induction lags are either the OH‐emission at 3075 Å or the interferometric density measurements. No significant difference appears between both measurements. According to the observations in a low temperature range, the overall activation energy corresponds to 22 Kcal/mole, while at higher temperatures the apparent activation energy is about 60 Kcal/mole. The results are discussed in terms of a branched mechanism, the chain branching reactions being rate determining below 2500 °K, while the initiation process takes over above this temperature. The low temperature mechanism confirms the interpretation given to flames burning in the same mixtures.