Non-premixed Combustion, Steady Diffusion Flamelet, ANSYS Fluent CFD Training

Description

Description

The present problem simulates the non-premixed combustion in a combustion chamber by ANSYS Fluent software. In the present case, it is assumed that the fuel and air enter the chamber from distinct boundaries and hence are considered Non-premixed.

The geometry of the present model is two-dimensional and has been designed using Design Modeler software. We do the meshing of the present model with ANSYS Meshing software. The mesh type is Structured, and the element number is 63280.

This CFD project is the 4th episode of the Combustion Training Course.

Non-Premixed Methodology

Non-premixed combustion model is used to model the combustion process. Non-adiabatic energy treatment and a steady diffusion flamelet model are used to model the combustion process.

First, a Chemkin mechanism is read in Fluent and used to create the flamelet (models a turbulent flame brush as an ensemble of discrete, steady laminar flames).

Next, a PDF table is generated to store data related to changes in temperature, density of mixture, and different chemical species mass fractions before simulation to be used during the main calculations.

Also, the Energy equation is On to calculate the changes in temperature due to the combustion process, and the Viscous is set as the Standard k-epsilon model.

Non-Premixed Conclusion

After the simulation process was finished, contours such as temperature, velocity, different species’ mass fractions, and streamlines were obtained. As shown in the temperature contour, the temperature has increased in the chamber, indicating that the combustion has taken place.

Also, the formed secondary flows in the chamber are shown in the streamlines. These secondary flows have the role of increasing the mixing process between fuel and air and hence enhancing the combustion process.