Prediction of turbulent non-premixed hydrogen flames using second-order conditional moment closure modelling

The advent of increasingly stringent emissions legislation inevitably leads to the requirement for more accurate modelling of pollutant formation in practical combustion applications. Previous limited success in modelling species such as NO, using first-order conditional moment closure (CMC) models indicates the need for more advanced modelling techniques. Here, a method of including higher-order chemistry within a one-dimensional, parabolic CMC framework is investigated, and applied to the prediction of three hydrogen jets of varying degrees of helium dilution. Interaction of the combustion model with both the k-epsilon and Reynolds stress turbulence models is examined. Results are encouraging and found to be in line with expectations. Suggestions are made in light of this to account for anomalous predictions of nitrous radical formation.