Premixed Combustion in a Porous Zone

Premixed Combustion in a Porous Zone, CFD Simulation ANSYS Fluent Training

Description

This project simulates premixed combustion within a porous zone using ANSYS Fluent, examining how the presence of porous media affects combustion behavior. Porous media combustion, often implemented through matrix-stabilized burners, works by allowing the flame to propagate through the solid matrix of a porous material rather than in free space. The solid matrix absorbs and redistributes heat through conduction and radiation, which tends to broaden the reaction zone, lower peak flame temperatures, and improve flame stability compared to conventional open-flame combustion. This approach is widely used in industrial burners and heating applications where more uniform heat distribution, reduced thermal peaks, and extended operational stability are desired — making the comparison between porous and non-porous combustion a valuable way to quantify these effects. The 3D geometry was designed in Design Modeler, consisting of two sections: a lower preheating region and an upper stable-burn region. The domain was meshed in ANSYS Meshing using a structured grid totaling 8,700 cells.

Methodology

This simulation models a simple premixed combustion case within a porous zone, examining how the porous structure influences combustion temperature and helps stabilize the flame — configured as a matrix-stabilized burner. Results were compared against an equivalent premixed combustion case without porosity to isolate the effect of the porous medium. The Species Transport model was used to represent the combustion process, with the incoming mixture flow set at a methane mass fraction of 0.23 and an oxygen mass fraction of 0.77. Combustion was initiated using the ignition spark sub-model. Gravitational effects were included at -9.81 m/s² along the y-axis, and turbulence was resolved using the SST k-omega model.

Conclusion

Results include 3D velocity fields, air and water volume fraction contours, and simulation animation. The findings show that the porous zone reduces static temperature within the combustion region and promotes a more uniform, stable combustion process compared to an equivalent case without porosity — consistent with the general behavior expected of matrix-stabilized porous burners, where the solid matrix's heat redistribution moderates and stabilizes the reaction zone.