Numerical modeling for multiple combustion modes in turbulent partially premixed jet flames

In this study, the multi-environment probability density function (MEPDF) model has been used to numerically investigate the flame structure under the multiple combustion modes with nearly homogeneous and inhomogeneous inlets. For nearly homogeneous and inhomogeneous cases, the MEPDF approach shows a good conformity with experimental data both conditioned statistics, and unconditioned mean and variance scalars. However, there exist the distinct discrepancies in the edge of reaction zone mainly due to the shortcomings of the RANS-based turbulence model. Predicted results indicate that the used model shows the limitation to describe the combustion processes with the local extinction in the downstream regions. With regard to the predicted conditioned environment scatters, the multienvironment PDF model has shown the capability to precisely simulate the nearly perpendicular shift from the fuel-rich side to the stoichiometric side. Based on the numerical results, detailed discussion was made for the characteristics of turbulent partially premixed jet flames with multiple combustion modes and the shortcomings of present model.