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

TL;DR

This paper introduces a novel application of the split-based extended quadrature method of moments (S-EQMOM) combined with LES for reconstructing soot particle size distributions in turbulent flames, achieving accurate predictions validated against experimental data.

Contribution

It demonstrates the effective integration of S-EQMOM with LES and flamelet models to accurately reconstruct soot PSD in turbulent flames, addressing limitations of classical MOM.

Findings

Good agreement with experimental soot volume fraction data.

Reconstructed PSD shows unimodal/bimodal distributions with particles smaller than 100 nm.

Soot intermittency is linked to mixture fraction fluctuations.

Abstract

The Method of Moments (MOM) has largely been applied to investigate sooting laminar and turbulent flames. However, the classical MOM is not able to characterize a continuous particle size distribution (PSD). Without access to information on the PSD, it is difficult to accurately take into account particle oxidation, which is crucial for shrinking and eliminating soot particles. Recently, the Split-based Extended Quadrature Method of Moments (S-EQMOM) has been proposed as a numerically robust alternative to overcome this issue (Salenbauch et al., 2019). The main advantage is that a continuous particle number density function can be reconstructed by superimposing kernel density functions (KDF). Moreover, the S-EQMOM primary nodes are determined individually for each KDF, improving the moment realizability. In this work, the S-EQMOM is combined with a Large Eddy Simulation/presumed-PDF flamelet/progress variable approach for predicting soot formation in the Delft Adelaide Flame III. The target flame features low/high sooting propensity/intermittency and comprehensive flow/scalar/soot data are available for model validation. Simulation results are compared with the experimental data for both the gas phase and the particulate phase. A good quantitative agreement has been obtained especially in terms of the soot volume fraction. The reconstructed PSD reveals predominantly unimodal/bimodal distributions in the first/downstream portion of this flame, with particle diameters smaller than 100 nm. By investigating the instantaneous and statistical sooting behavior at the flame tip, it has been found that the experimentally observed soot intermittency is linked to mixture fraction fluctuations around its stoichiometric value that exhibit a bimodal probability density function.