Oxygen Effect on Combustion CFD Simulation, ANSYS Fluent Training

Oxygen is an essential reactant in the processes of combustion. Oxygen supply affects combustion efficiency, flame temperature, combustion completeness, and emission production. Insufficient oxygen can cause incomplete combustion, releasing carbon monoxide and unburned hydrocarbons. Conversely, abundant oxygen can boost combustion efficiency but also increase thermal NOx generation. To maximize performance and reduce environmental impact, combustion oxygen concentration must be understood and optimized.

In this study, we investigate the oxygen effect on combustion by means of ANSYS Fluent. The study intends to seek two case results in which there is a 10% oxygen difference. Thus, both are assumed to complete reactions.

Simulation process

The cylindrical shape of the combustion chamber is produced by considering a 2D section of it revolving around the axis of rotation, utilizing an Axisymmetric tool. The generation of a structured grid has helped create a high-quality grid.

The volumetric reaction of methane and air is modeled by Species Transport module. The combustion turbulence model is Eddy Dissipation. Fuel and air are injected from two different nozzles and then meet each other in the combustion chamber.

Post-processing

The impact of excess air may not be very clear in the contours. However, it shows that having 10% excess air could not react with the fuel and simply leave the domain. Notably, we are not considering nox generation, and due to the high temperature inside the combustor, excess air can negatively affect and produce undesirable products. For a deeper understanding, we recommend you remodel the problem, this time considering soot and NOx generation.