A probability density function (PDF)-based combustion modeling approach for RANS simulation of a jet issuing into a hot and diluted coflow is performed. A tabulated chemistry-based model, i.e., flamelet-generated manifold (FGM), is adopted in the PDF method. The manifolds are constructed using igniting counterflow diffusion flamelets with different coflow compositions. To handle the inhomogeneity of the coflow and the entrainment of the ambient air, a second mixture fraction is defined to quantify the mixing of a representative coflow composition with the ambient air. The chemistry is then parameterized as a function of two mixture fractions and a reaction progress variable. To assess the modeling approach, Adelaide JHC flames, namely HM1, HM2, and HM3, having different oxygen concentrations in the hot coflow, 3%, 6%, and 9% O₂, respectively, have been simulated for Reynolds number (Re) = 10,000. Profiles of mean mixture fraction and major species are accurately captured by the model along with the mean temperature. The mean temperature profiles are also captured nicely, while the sensitivity of progress variable (PV) on the predictions is highlighted. ... Read more

A probability density function (PDF) based combustion modeling approach for RANS is used in the simulation of a jet issuing into a hot and diluted coflow. A tabulated chemistry based model, i.e. Flamelet Generated Manifold (FGM), is adopted in the PDF method. The manifolds are constructed using igniting counter-flow diffusion flamelets with different coflow composition. To handle the inhomogeneity of the coflow and the entrainment of the ambient air, a second mixture fraction is defined to quantify the mixing of a representative coflow composition with the ambient air. The chemistry is then parameterized as a function of two mixture fractions and a reaction progress variable. Two flames, namely HM1 and HM3, having different oxygen mass concentration in the hot coflow, 3% and 9% O2 respectively, have been simulated for Reynolds number (Re) =10000. The mean oxygen concentration and temperature profiles are well predicted showing the capability of the tabulated chemistry. Profiles of mean mixture fraction and major species are also accurately captured by the model. ... Read more