A new single-step mechanism for hydrogen combustion
Résumé
A single-step chemical-kinetic mechanism is developed that provides good predictions of laminar burning velocities and auto-ignition times. Reasonably accurate adiabatic flame temperatures and (consequently) total amounts of heat release are first obtained through asymptotic expansions of equilibrium expressions for the production of H, O, and OH radicals from the stable products, H 2 O along with H 2 and O 2 . By ignoring the inner flame structure, this yields minimal computational stiffness for a wide range of equivalence ratios and pressures. In the single-step rate expression, a passive scalar carrying the radical pool is then introduced that enables reasonable laminar flame structures and burning velocities to be calculated. An additional passive scalar measuring pre-heat-release radical build-up serves to track auto-ignition properly as well, thereby providing reasonable predictions for time-dependent as well as steady-state conditions. The results from this computationally convenient formulation are useful for describing a number of combustion processes, including counter-flow flames.
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