Numerical simulation of local extinction effects in turbulent combustor flows of methane and air

Identification of local extinction topology in axisymmetric bluff-body diffusion flames with a reactedness-mixture fraction presumed probability density function model

“…Opposite to previously employed extinction criteria (e.g. Obounou et al [9] and Gran et al [10]), where the local Damkohler was compared with an arbitrarily chosen critical level (e.g. Da 5 1), the present formulated criterion allows a wider flexibility by relating the local Damkohler to local turbulent scalar mixing and chemical parameters that vary with time, position and local flame structure conditions.…”

“…As modelling requirements are significantly increased with respect to jet flames, multi-scalar approaches can sometimes be avoided and finite-rate chemistry effects can be addressed by parameterizing the local gas state in terms of a Damkohler number and by using appropriate extinction criteria [9,10]. The development of such methods relies crucially on detailed measurements of the local turbulent flame structure close to extinction [11].…”

Prediction of a Turbulent Non-Premixed Natural Gas Flame in a Semi-Industrial Scale Furnace using a Radiative Flamelet Combustion Model

“…For calculations of industryrelevant gaseous flames, simplified equilibrium combustion models based on either the conserved scalar with a presumed probability density function (PDF) or the eddy break-up approach together with the isotropic eddy-viscosity based k − ε turbulence model are frequently employed. Previous numerical studies (e.g., [1][2][3][4][5]) of flames in geometries relevant to practical combustors have demonstrated that such combustion modelling approaches are unable to capture the important effects of finite-rate reactions such as ignition, extinction and flame structure. In order to enhance the quality of predictions, advanced turbulent combustion models such as laminar flamelet approaches [6,7], conditional moment closure (CMC) [8] and transported PDF method [9] are needed.…”

Numerical study of bluff-body non-premixed flame structures using laminar flamelet model

“…The scalar dissipation rate acts as the parameter to include finiterate chemistry effects in the turbulent combustion. In theory, the laminar flamelet model is capable of prediction of local extinction [12,13]. If the scalar dissipation rate exceeds a critical value, the extinction limit, the flame is quenched and the flamelet is represented by a pure mixing flamelet.…”

“…However, Hossain [16] has shown that the strain rate or the modified scalar dissipation rate is not capable of reproducing temperature and mass fraction of major and minor species. Gran et al [13] showed that laminar flamelet model with two flamelet libraries, one for burning flamelet and one for extinguished flamelet, could predict the local extinction. However, the experimental data used for the validation of the model were rather limited.…”