Technique for the Rapid Generation of OH Radicals Behind Shock Waves and Its Application to the Study of Combustion Kinetics

摘要

A technique for the fast, thermal generation of hydroxyl radicals behind shock waves, useful for the controlled study of elementary reactions involving OH, has been developed. The technique is based on the fact that the room-temperature equilibrium of the reaction NO + NO sub 2 + H sub 2 O reversible 2HNO sub 2 favors the production of HNO sub 2 (nitrous acid). At the high temperatures present behind shock waves, HNO sub 2 dissociates rapidly to OH and NO, providing a fast, controllable source of hydroxyl radicals. By measuring the concentration time-history of the OH thus generated in the presence of known amounts of reactants (such as hydrocarbons), the rate coefficient of the generic reaction OH + Re implies Products (Re = reactant) can be inferred. For illustrative purposes, the method was applied to the determination of the relatively well-known rate coefficients of two reactions of interest in combustion, OH + OH implies O + H sub 2 O and OH + CH sub 4 implies CH sub 3 + H sub 2 O. (ERA citation 09:006350)