Steady-state RANS simulation of a swirling, non-premixed industrial methane-air burner using edcSimpleFoam

At the 6th OpenFOAM workshop in June 2011 new solvers for turbulent non-premixed combustion, edc{Simple,Piso}Foam, including radiation modeling based on the open source CFD-library OpenFOAM were released to the public. This report gives a short evaluation of the steady-state solver edcSimpleFoam. edcPisoFoam is the unsteady counterpart. edcSimpleFoam implements two selectable versions of Magnussen's Eddy Dissipation Concept: EDC/LE and EDC/PSR (Local Extinction and Partially Stirred Reactor respectively).

OpenFOAM is not famous for combustion modeling. Compared to commercial products the selection of solvers and models for reactive flows and combustion is very limited. It was found earlier by the authors that the Chalmers PaSR (Partially Stirred Reactor) model which is the basis of the standard solver reactingFoam can not produce grid-independent results even for simple 2D diffusion flames (this can be tested easily in the included tutorial case in OpenFOAM-1.7.1). Also the solver is unsteady which is a major drawback for industrial applications due to the small time step sizes and the resulting huge CPU-times involved to reach sufficient simulation time for variable averaging (e.g. temperature, species concentration, velocity). Both shortcomings are unacceptable for physically correct and efficient simulations of typical highly turbulent non-premixed burners in the authors' point of view.

Simulation results using edcSimpleFoam and the EDC/LE-submodel of the burner at full load are shown at the bottom. The case was converged after approx. 70000 Iterations.

Velocity magnitude in m/s (left) and y-velocity in m/s (right)

Temperature in K (left) and radiation intensity in W/m² (right)

Oxygen mass fraction (left) and carbon dioxide mass fraction (right)

Methane mass fraction (left) and nitrogen mass fraction (right)