Combustion: Combustion Chamber, Transient Solver

This project simulates a combustion chamber in ANSYS Fluent using a transient, pressure-based solver with the effect of gravity included. Combustion is the central theme of the study: methane is burned with air inside the chamber, and the simulation is built around capturing the chemical reaction, the resulting heat release and the way the hot products move through the geometry. The chamber comprises three main parts — the air inlet pipe, the burner section and the outlet pipe — and contains a thin internal wall pierced by cavities of varying size. The small primary holes cool the chamber wall through a layering film of flow, while the larger holes help anchor the flame in the centre of the chamber, a configuration typical of real combustor liners.

The geometry is three-dimensional and was created in Design Modeler. Meshing was performed in ANSYS Meshing using an unstructured triangular grid of 694,928 elements.

Because the flow inside a combustor is complex and highly turbulent, the RNG k-ε turbulence model with standard wall functions is used. Combustion itself is represented through the Species Transport model, which is the heart of the setup: it tracks each chemical constituent and the reactions that convert reactants into products while releasing energy. Air and fuel (CH₄) enter at mass flow rates of 0.02 kg/s and 0.0006 kg/s respectively, both at 300 K, and the chamber's outer wall is treated as adiabatic. The reaction is modelled as a two-step methane–air combustion involving six species — methane, oxygen, nitrogen, water vapour, carbon dioxide and carbon monoxide — with the inlet air composed of oxygen and nitrogen at mass fractions of 0.23 and 0.77.

The results are presented as three-dimensional volume renderings and streamlines of velocity, pressure, temperature, density and the mass fractions of the participating species, giving a detailed view of the combustion process. Air enters around the periphery and the methane–air mixture from the bottom surface, meeting to form the combustion region. There, temperature and pressure rise sharply as the reaction proceeds, and the heated flow accelerates toward the outlet — the central behaviour the simulation sets out to capture. As a study in combustion modelling, the project demonstrates how a species-transport, multi-step reaction approach combined with a transient solver can reproduce flame stabilisation, heat release and the transport of combustion products through a realistic combustor geometry.