A Noble Kinetic Model of H2/O2 System Applicable to Liquid Rocket Engine Combustion

Abstract

A chemical kinetic model for high pressure combustion of H2/O2 mixtures has been developed. Some of the rate constants important in high pressure conditions were updated. Particular attention has been paid to different channels of the H+HO2 reaction, and to the third body efficiency in the H+O2+M and H+OH+M reactions. An analysis of the performance of an updated model is presented by comparing with various experimental data. Although the present model could reproduce most of shock tube data of ignition delay with variety of bath gases, there is still some discrepancy in the pressure dependence of flame speed between model predictions and recent experimental data. These models were validated against a wide range of experimental conditions and, in general, were found to be in good agreement with various experimental data including shock tube ignition delay, flow reactors, and laminar flame speed measurements. Basic characteristics of hydrogen combustion are now well understood because of those excellent modeling works and related experimental studies. Most recent kinetic model of Konnov 3 is probably the most extensively validated. The modeling range covers ignition delay measurements by shock tubes from 950 to 2700 K and from the atmospheric pressure up to 87 atm, and flow tube experiments at around 900 K with pressures from 0.3 to 15.7 atm. The mechanism is also validated against laminar flame burning velocities up to 4 atm. However, as pointed by Konnov, there is still some discrepancy between the model prediction and the measured flame velocities of hydrogen-oxygen-inert gas mixtures at higher pressures. The pressure dependences of mass burning rates for hydrogen mixtures have recently been studied experimentally and numerically by Burke et al. 4 . Flame speeds and mass burning rates were measured for equivalence ratios from 0.85 to 2.5, pressures from 1 to 25 atm. They found that the mass burning rate is increasing with pressure at low pressures, while at grater pressures, the mass burning rate is found to decrease with pressure. At lower pressures, predictions using recently published chemical kinetic models agree well with experimental data. However, the predicted mass burning rates differ significantly from model to model. Burk et al. suggested that