engleski

Large Eddy Simulation of Turbulent Premixed Combustion of Laboratory-Scaled Flames

This work presents numerical approach for simulation of turbulent premixed flames in large eddy simulation (LES) framework, based on the Coherent Structure Method (CSM). Two flames will be simulated: the highly stretched flame F2 and swirling flame PSF-30. CSM smoothly modifies Smagorinsky coefficient Cs as a function of local coherence in the flow. The aim of this work is to show that CSM SGS model can be used as a general approach for modelling of the turbulent transport in wide variety of laboratory-scale turbulent premixed flames, especially when compared with two standard Smagorinsky approaches, where Cs is kept constant. Both flames were simulated with three SGS approaches, the CSM approach and two constant values of Cs, Cs = 0.1 and Cs = 0.2. The three approaches are also compared on the basis on the domain-integrated resolved-to-total ratio and cell residual values of turbulent kinetic energy and flame surface density (FSD). Simulation results show that all approaches for Cs are showing good agreement with experimental in terms of the mean flame velocity and reaction progress variable (RPV), but CSM approach provides better results of the RMS values. In all cases the resolved-to-total ratio of the turbulent kinetic energy was above 80%, but significantly lower for FSD. The domain-integrated cell residuals were below 1% for the flame F2 and below 3% for flame PSF- 30.

Turbulent premixed combustion; computational fluid dynamics (CFD); large eddy simulation (LES); coherent structure method (CSM); laboratory-scaled flames; cell residual error estimator

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