The validity of the commonly used flame marker for heat release rate (HRR) visualization, namely the rate of the reaction OH + CH2O ⇔ HCO + H2O is re-examined. This is done both for methane–air and multi-component fuel–air mixtures for lean and stoichiometric conditions. Two different methods are used to identify HRR correlations, and it is found that HRR correlations vary strongly with stoichiometry. For the methane mixture there exist alternative HRR markers, while for the multi-component fuel flame the above correlation is found to be inadequate. Alternative markers for the HRR visualization are thus proposed and their performance under turbulent conditions is evaluated using DNS data.ZMN and NS acknowledges the funding through the Low Carbon
Energy University Alliance Programme supported by Tsinghua
University, China. ZMN also likes to acknowledge the educational
grant through the A.G. Leventis Foundation. This work made use
of the facilities of HECToR, the UK’s national high-performance
computing service, which is provided by UoE HPCx Ltd at the
University of Edinburgh, Cray Inc. and NAG Ltd., and funded by
the Office of Science and Technology through EPSRC’s High End
Computing Programme.This is the final published version. It first appeared at: http://www.sciencedirect.com/science/article/pii/S0010218014001606#