  The present paper reports on the assessment of different turbulence-chemistry
interaction closures for modeling turbulent combustion in the Moderate and
Intense Low oxygen Dilution combustion regime. 2D RANS simulations have been
carried out to model flames issuing from two burners DJHC burner and Adelaide
JHC burner which imitate the MILD combustion. In order to model these flames,
two different approaches of turbulence-chemistry interaction models are
considered; while in the PDF based modeling, two different variants are invoked
to understand the applicability of the PDF based models in the MILD regime: one
is based on presumed shape PDF approach and the other one is transported PDF
approach. A comprehensive study has been carried out by comparing the results
obtained from these different models. For the DJHC burner, the computations are
carried out for a jet speed corresponding to Reynolds numbers of Re=4100,
whereas the Adelaide JHC burner computations are performed for a jet speed
corresponding to Reynolds number of Re=10000. The effects of molecular
diffusion on the flame characteristics are also studied by using different
micro-mixing models. In the case of DJHC burner, it has been observed that the
mean axial velocity and the turbulent kinetic energy profiles are in good
agreement with the measurements. However, the temperature profiles are
over-predicted in the downstream region by both EDC and the PDF based models.
In the context of Adelaide JHC burner, the profiles of the temperature and the
mass fraction of major species (CH4, H2, O2, H2O, CO2) obtained using LPDF
approach are in better agreement with the measurements compared to those
obtained using EDC model; although, both the solution approaches fail to
capture CO and OH radical profiles.
