Modelling and calculation of a partially premixed turbulent flame

A partially premixed turbulent flame has been modelled using the laminar flamelet concept, i.e. the assumption that laminar flames are embedded in the turbulent flow field. A combination of a premixed flamelet model and a diffusion flamelet model has been used for modelling this partially premixed flame. The premixed flamelet model uses a level set function G(x, t) and the diffusion flamelet model is based on the equation for the mixture fraction Z(x, t). To treat the turbulence closure problem use has been made of the standard k-Ε model. Favre-averaged scalar quantities have been calculated from so-called flamelet libraries by making use of a presumed Probability Density Function (PDF) method. To evaluate the model, calculations for a partially premixed Hydrogen flame have been compared to measurement data of Wu et al. (1990). A good agreement has been found for the location of the premixed flame as well as for the turbulent flame brush thickness.