Soot emission radiation–turbulence interactions in diffusion jet flames

Abstract

The objective of this article is to perform a detailed study of the local and global interactions between soot emission and turbulence. Five turbulent jet diffusion flames with different Reynolds numbers and sooting propensities are investigated by using a hybrid flamelet/transported composition PDF and well-established sub-models for soot production and radiative heat transfer. This approach leads to an exact closure for the emission turbulence radiation interaction. The PDF transport equation is solved using the stochastic Eulerian fields method. Model results show that turbulence–radiation interaction tends to enhance soot emission owing to the temperature self-correlation. In addition, the cross correlation between soot volume fraction and temperature is found to be strongly negative in the regions dominated by soot radiation whatever the Reynolds number and the fuel sooting propensity. Two mechanisms are found to be responsible for this negative behaviour. The first is directly related to the structure of the turbulent jet flame whereas the second is due to the soot emission process itself. This negative correlation limits the effects of the temperature self-correlation and this limitation increases with the turbulence intensity.