Updated Kinetic Mechanism for High-Pressure Hydrogen Combustion

A chemical kinetic model for high-pressure combustion ofH2=O2 mixtures has been developed by updating some of the rate constants important under high-pressure conditions without any diluent. The revised mechanism is validated against experimental shock-tube ignition delay times and laminar flame speeds. Predictions of the present modelarealsocomparedwiththosebyseveralotherkineticmodelsproposedrecently.Althoughpredictionsofthose models (including the present model) agree quite well with each other and with the experimental data of ignition delay times and flame speeds at pressures lower than 10 atm, substantial differences are observed between recent experimental data of high-pressure mass burning rates and model predictions, as well as among the model predictions themselves. Different pressure dependencies of mass burning rates above 10 atm in different kinetic models result from using different rate constants in these models for HO2 reactions, especially for H HO2 and OH HO2 reactions.TherateconstantsforthereactionH HO2 involvingdifferentproductchannelswerefound to be very important for the prediction of high-pressure combustion characteristics. An updated choice of rate constants for those reactions is presented on the basis of recent experimental and theoretical studies. The role of O 1 D, which can be produced by the H HO2 reaction, in the high-pressure combustion of H2 is discussed.