Direct numerical simulation of a supersonic lifted hydrogen jet flame: A priori study on combustion models

In this study, a systematic assessment of turbulent combustion submodels of conditional moment closure (CMC) has been conducted using DNS data of a three-dimensional spatially-developing supersonic lifted hydrogen flame with a Mach number of 1.2 at the jet injection. It has been found that Beta pdf of mixture fraction can well capture the mixing space of the high speed reacting flow. The linear model exhibits a good performance for the axial velocity predictions. Girimaji's model for scalar dissipation rate performs well at upstream, while the AMC model presents better further downstream. The first order closure for the conditional reaction rate deviates a lot from the DNS extracted results. Second-order corrections made to temperature only or to the two rate-limiting reaction steps induce improvement, still with much discrepancy. Second order closure considering fluctuations of all the reacting species and temperature can accurately reproduce the DNS results. (C) 2014 IAA. Published by Elsevier Ltd. All rights reserved.