On Modeling Aspects of Swirling Stabilized Diffusion Flames

Modeling of swirling stabilized diffusion flames in a cylinder combustor is considered. Two-equation turbulence models are inherently not well suited to handle swirling turbulent flows. We propose an LES based solver for the computation of the reacting flow fields. LES data is used to study the influence of inlet swirling motion on the combustion and the turbulent mixing process. PDF is extracted from the LES data. The shape of PDF profiles is similar to a ft—distribution. PDF distributions at different locations indicate that mixing of fuel and air is improved by increase of inlet swirl angle. Spectral analysis of different terms of the turbulent kinetic energy balance equation shows that the contribution of the heat release to turbulent kinetic energy balance decreases with the frequencies. We also used the LES data to assess the appropriateness of conventional eddy viscosity based gradient-diffusion models for accounting for the density-turbulence and temperature-turbulence correlations.