Modeling of turbulent lifted flames in vitiated co-flow using multi environment Eulerian PDF transport approach

In the present study, two turbulent lifted flames are numerically investigated and reported. To model the turbulence-chemistry interaction, presumed shape multi-environment Eulerian PDF transport method (MEPDF) is invoked in conjunction with IEM (interaction by exchange with mean) model for micro-mixing closure. The MEPDF approach represents the joint composition PDF with a presumed shape as a set of Delta functions. Using the definition of the PDF shape into PDF transport equation, the MEPDF approach represents the PDF transport equation by a set of governing equations for the probability of occurrence in any environment and the probability weighted species mass fractions, which are solved in an Eulerian frame using commercial CFD code, ANSYS Fluent. Initially, the flame properties such as mixture fraction, temperature, species mass fraction are reported and compared with the measurements. Due to presumed shape assumption of the PDF, the final transport equations have an additional source terms called correction source. Therefore, a parametric study has also been carried out by changing the micro mixing constant and the correction sources in order to study the impact on the species and temperature field as well as on the prediction of the lift off height. Moreover, the discrepancies of the current predictions with the experimental data have been quantified and discussed. It is also observed that the current predictions are reasonably accurate with small number of environments (2), thereby making the model computationally very attractive in comparison to the Lagrangian solution of the PDF transport equations.