Doubly Conditional Source-term Estimation (DCSE) for the modelling of turbulent stratified V-shaped flame

A partially premixed formulation of Conditional Source-term Estimation including doubly conditioned averages, namely DCSE, is applied to several turbulent stratified V-shaped flames using a Reynolds Averaged Navier Stokes (RANS) approach. Three different stratification levels are considered with different turbulence conditions. In contrast to the authors' initial work (Dovizio et al., 2016), a more elaborate closure of the scalar dissipation rate is implemented in the progress variable variance equation, where a dependence on the local value of the equivalence ratio is considered. Detailed chemistry is included. Good predictions are obtained for the mean axial and transverse velocity components, and progress variable compared to experimental data for the stoichiometric cases, in particular for the lean and rich cases, where the predictions are significantly improved compared to previous numerical studies. The flame thickness is found to be reduced when the stratification increases, consistent with experimental findings. Future work will examine the closure of cross-dissipation terms in the transport equations and the DCSE implementation in LES. (C) 2016 The Combustion Institute. Published by Elsevier Inc. All rights reserved.