Soot evolution in turbulent non-premixed bluff body flames: Assessment of detailed soot formation models using large eddy simulation

Exploring the complexities of soot formation in combustion systems implies recognizing the intricate interplay among turbulence, chemical kinetics, radiation, and soot particle dynamics. Achieving accurate predictions of soot levels in turbulent flames entails a meticulous representation of all stages of soot formation and oxidation, which prompts the development and use of detailed soot formation models. This work delves into three detailed soot models-Method of Moments with Interpolative Closure (MOMIC), Hybrid Method of Moments (HMOM), and Discrete Sectional Method (DSM)-integrated into the open-source computational tool OpenFOAM. Both the combustion process and the formation of soot precursors in the gas phase are characterized using the Flamelet Progress Variable combustion model along with the detailed ABF chemical kinetic mechanism. Turbulence is addressed through a Large Eddy Simulation based approach, and the computational results are compared with experimental data from the Adelaide ENB1 Bluff Body Flame. Specifically, the analysis extends to detailing flow velocities and their fluctuations, along with fields and profiles depicting soot volume fraction. In order to obtain quantitatively correct soot volume fractions, the nucleation sticking factor was adjusted. The comparative assessments of the soot formation models carried out provide a unique perspective on soot formation, highlighting different effects of each soot source terms and specific model limitations. HMOM described the measured soot volume fraction with greatest accuracy followed by DSM and MOMIC.