Description

In this project, the steady combustion of methane and air in a simple extended cubical combustion chamber is investigated by ANSYS Fluent software. We perform this CFD project and investigate it by CFD analysis.

Radiation heat transfer must be considered since combustion chambers undergo extremely high temperatures.

The present model is designed in three dimensions using the Design Modeler.

The meshing of the present project has been done using ANSYS Meshing software. The element number is 384112.

Radiation Heat Transfer Methodology

In this project, the mixture’s static temperature has a maximum value of 3500 k within the chamber. Methane and air enter the domain from inlets, in which methane is injected into the domain using only one inlet.

However, airflow is injected using two inlets to achieve an approximately uniform mixture of fuel and air. The mass flow rate of air and fuel entering the domain equals 0.00468 and 0.000205 kg/s.

The chemical reaction between methane and air produces CO2 and H2O, and since the combustion is air-rich, oxygen and nitrogen are left unused at the end of the reaction. Therefore, the species transport model has been activated to simulate combustion, and volumetric reactions are enabled.

Moreover, due to the high temperature inside the combustion chamber, the heat transfer due to the radiation must also be considered; thus, the Discrete ordinates (DO) model has been enabled too.

Finally, the RNG k-epsilon model is used to solve the turbulent fluid equations. This sub-model provides the advantage of capturing intense heat flux generation inside the domain better than the other k-epsilon sub-models

Radiation Heat Transfer Conclusion

At the end of the solution process, two-dimensional contours related to the temperature, velocity, species mass fraction, streamlines, velocity vectors, etc., inside the combustion chamber are obtained. The mixture mass flow rate at the outlet is equal to 0.004885042 kg/s.

The main combustion process takes place in the combustion chamber itself. This can be explicitly seen in the contour of temperature reaction heat, which shows that the maximum temperature gradient and maximum reaction heat are observed.

Also, the occurrence of the combustion process is clear in species mass fraction contours. For instance, the CO2 mass fraction contour shows how the mass fraction of CO2 increases suddenly due to the combustion process.