The current study focuses on the modelling of turbulent premixed or partially
premixed flames over a wide range of combustion regimes using various fuels. Opposed
flows featuring fractal-generated turbulence are examined using different classes
of models. The reacting case is in the flamelet regime of combustion and two-scalar
joint β -bimodal presumed PDF and transported PDF approaches are applied for
scalar statistics. In the isothermal case the k − ε model works comparatively well,
in contrast to previous studies, while in the reacting case the second moment closures
are outperforming the eddy viscosity based closures. The transported PDF
approach indicates an under-prediction of the turbulent burning velocity in this
flow. The latter approach is therefore applied to compute freely propagating turbulent
premixed flames using comprehensive chemistry. Turbulent burning velocities
are extracted and compared with experimental data. The computed cases are covering
the laminar flamelet to the distributed reaction zone regime. The mixture
reactivity is also varied through different fuel/air mixtures and explored in terms
of the Zeldovich number. The fuel/air composition studied include fuel-lean CH4,
stoichiometric CH4 and C2H6 and fuel-rich H2 mixtures. The impact of molecular
transport is investigated through the inclusion of an explicit analytical formulation.
A multi-scale scalar dissipation rate closure that accounts for the influence of the
Da number is extended in a simple manner to include Le number effects. An industrial
swirl-stabilised partially premixed fuel-rich CH4 flame is simulated at realistic
gas turbine conditions using the node-based Eulerian transported PDF approach
coupled with a second moment closure for the velocity field. The case is in the well
stirred reactor regime and the chemical kinetics is modelled using a global reaction
scheme for hydrocarbon combustion. The flow field is initialised and compared with
the predictions of the two-scalar joint β-bimodal presumed PDF approach.