An updated model and discussion of modeling challenges in high-pressure H₂/O₂ flames

An updated H₂/O₂ chemical-kinetic model based on that of Li et al. [Int. J. Chem. Kinet. 36 (2004) 566-575] is presented to address the difficulties observed in modeling recent high-pressure flame data. Emphasis is placed on assessing the current state of knowledge of relevant elementary processes and the approach needed to achieve a rigorous solution that yields quantitative predictive capability across a wide range of conditions. The primary intent of the updated model is to incorporate a number of rate constant expressions that are more consistent with elementary reaction studies. However, substantial fundamental issues and rate constant uncertainties still remain. The updated model reproduces the homogeneous validation targets used in Mueller et al. [Int. J. Chem. Kinet. 31 (1999) 113-125] and Li et al., flame speed validation targets used in Li et al. within ∼10%, and the recent dilute high-pressure burning rate measurements of Burke et al. [Combust. Flame (2010) doi:10.1016/j.combustflame.2009.08.009] within ∼25% (compared to ∼50% for Li et al.).