Partially Premixed Turbulent Combustion Model Based on Joint Statistics of Progress Variable, Mixture Fraction, and Scalar Dissipation Rate

The authors use a probability density function method in which a transport equation for thejoint probability density function of velocity, turbulence frequency, progress variable, mixture fraction, and enthalpy was solved. Based on a new combustion model, this information was used to obtain the joint statistics of the compositions. The extinction and reignition of fluid particles is controlled by a particle progress variable and its scalar dissipation rate. Precomputed flamelets are only employed for particles in the flammable mixture fraction range. Outside of this range, the particle enthalpy is evolved by a mixing model (similar to the mixture fraction). Numerical test cases of lifted turbulent diffusion flames with a considerable amount of local extinction show the ability of the model to account for the major physical effects and comparisons with experimental data show good agreement.