Validation of unsteady flamelet / progress variable methodology for non-premixed turbulent partially premixed flames

This paper highlights the modeling capabilities of UFPV approach for the modeling of turbulent partially premixed lifted flames to capture the extinction and re-ignition phenomena. Large eddy simulation (LES) with the probability density function (PDF) approach provides the turbulence-chemistry interaction. All scalars are represented as a function of mean mixture fraction, mixture fraction variance, mean progress variable and scalar dissipation rate. Mixture fraction is assumed to follow a β-PDF distribution. Progress variable and scalar dissipation rate distributions are assumed to be a δ-PDF. Results are compared with experimental data of a vitiated co-flow burner with fuels like CH4/Air and H2/N2. Results of radial plots for temperature, mixture fraction and scattered data of temperature with mixture fraction at various axial locations are compared. Lift-off height for a CH4/Air flame appears to be over-predicted while the predicted lift-off height for a H2/N2 flame shows an under-prediction.