Non-Premixed Combustion: Non-Adiabatic Chemical Equilibrium

Non-Premixed Combustion, Non-Adiabatic, Chemical Equilibrium, ANSYS Fluent CFD Training

Description

This project simulates non-premixed combustion under non-adiabatic conditions inside a two-dimensional combustion chamber using ANSYS Fluent, focusing on the chemical equilibrium approach to reaction modeling. This provides insight into real-world combustion behavior where fuel and air enter the chamber through separate inlets, mixing and reacting only within the chamber itself.

The geometry was designed in Design Modeler and meshed in ANSYS Meshing using a structured grid totaling 63,280 elements.

Methodology

The Non-Premixed Combustion model was used to represent the combustion process, applying a non-adiabatic energy treatment to realistically capture heat transfer effects, alongside a chemical equilibrium approach for predicting species concentrations throughout the domain. Since fuel and air enter through separate inlets, this setup closely mirrors the mixing and reaction dynamics found in real combustion chambers.

A key component of this approach is a pre-generated Probability Density Function (PDF) table, which stores data on temperature variation, mixture density, and species mass fractions ahead of the main solution — substantially improving computational efficiency while providing a robust framework for chemical equilibrium calculations. The energy equation was enabled to accurately track temperature changes, with turbulence modeled using the standard k-epsilon model.

Conclusion

Results include temperature distribution contours, velocity profiles throughout the chamber, mass fractions for the various chemical species, and streamlines revealing the resulting flow and mixing patterns. These results offer insight into how combustion progresses within a non-premixed environment, how non-adiabatic conditions shape temperature evolution, how species form and are consumed throughout the reaction, and how secondary flow structures enhance mixing and overall combustion efficiency.

These insights are directly applicable to designing more efficient industrial furnaces and combustors, optimizing fuel injection systems in gas turbines, and improving combustion chamber geometry for reduced emissions in real-world non-premixed combustion applications.