Soot modeling in turbulent diffusion flames: review and prospects

Abstract

This work reviews the state-of-the-art of the main soot modeling approaches used in turbulent diffusion flames. Accordingly, after a short introduction about the subject addressed here, the main soot formation mechanisms are described next. This description provides the basis for the discussions about the different soot modeling techniques employed nowadays for soot predictions. Since combustion and radiation models have a significant impact on soot predictions, as a consequence of the strong coupling between chemistry, turbulence and soot formation, a general overview about these models is also provided. For the sake of clarity, the main soot formation models reviewed in this work are classified as semi-empirical soot precursor models and detailed ones. Both advantages and disadvantages of the referred soot modeling approaches are properly discussed. In the last part of this review, comparative results obtained using some of the main soot models currently available are presented along with a discussion about the prospects for soot modeling in turbulent flames. Finally, some conclusions and references are provided.Overall, based on the literature reviewed, it is concluded that there is yet a long path to be followed before understanding first and having then a soot model able to properly describe the formation of this critical pollutant for a variety of situations of industrial interest.

Parametric Study of Empirical Constants Used in Soot Formation Models Based on Interpolative Closure Methods of Moments

“…These regimes are classified as a function of the Knudsen number, = ⁄ , where is the gas mean free path and is the soot particle diameter (Kazakov and Frenklach, 1998). Further details about this formulation are given in Valencia et al (2021a).…”

“…Another negative impact of soot is that it alters the cloud formation process, acting as a condensation nucleus (Wang, 2011). The study of soot is also motivated by the need to optimize HC combustion systems and fill the knowledge gaps of the physical and chemical mechanisms controlling soot formation (Valencia et al, 2021a). In this context lies the importance of using computational fluid dynamics (CFD) based approaches and the development and use of soot formation models that can properly predict soot formation under different reactive flow conditions.…”

“…Deterministic models include the method of moments and the sectional method, whose most used variants include the MOM with interpolative closure (MOMIC) and the discrete sectional method (DSM). Although MOMIC is not considered as being as accurate as the DSM, it has a relatively low computational cost, needing the solution of only a few (generally three) additional transport equations to obtain the PSDF (soot particle size distribution function) (Valencia et al, 2021a).…”

Soot particle size distribution reconstruction in a turbulent sooting flame with the split-based extended quadrature method of moments

“…In recent years, LESs [3,5,9,13,16] and DNSs [8,[17][18][19][20] of turbulent sooting flames have improved soot prediction, yielding a deeper understanding of the interaction between turbulent reacting flows and soot formation. Reviews on numerical studies can be found in [21][22][23]. In [8,19], a DNS of a turbulent non-premixed n-heptane/air flame was performed to analyze the interactions of turbulent mixing, detailed chemical reactions, and soot formation.…”

Non-Premixed Turbulent Combustion Modelling of a Bluff-Body Flame Using a Flamelet Progress Variable Approach

“…All numerical simulations are carried out using the open source computational tool OpenFOAM, version v2006 (OpenCFD, 2020. Due to the strong coupling between chemistry, turbulence and soot formation, the combustion model has a significant impact on soot predictions (Valencia et al, 2021). Accordingly, this work represents an additional effort towards the long-term goal involving the development of a numerical framework to properly describe soot formation in turbulent combustion processes.…”