Numerical study on fractal-like soot aggregate dynamics of turbulent ethylene-oxygen flame

Abstract

The soot aggregate dynamics of turbulent ethylene-oxygen flame is numerically studied for different equivalence ratios and jet Reynolds numbers (Rej). Our developed Taylor-series expansion method of moments (TEMOM) model in our previous research studies is further extended to solve the bivariate population balance equation (PBE) and formulate the novel Bivariate TEMOM model scheme. Full numerical validations are performed with the stochastically weighted operator splitting Monte Carlo method and moving sectional method, the Bivariate TEMOM model scheme coupled with large eddy simulation (LES) method and soot formation model is used to simulate fractal-like soot aggregate dynamics in turbulent ethylene-oxygen flame. The results show that soot nucleation and surface growth processes are enhanced with increasing equivalence ratio while the coagulation rate is hardly varied as the total soot volume fraction is quite low. The increasingly uniform distributions of fractal dimension and particle size can also be observed. As Rej increases from 14,400 to 36,000, both the mean diameter and mean fractal dimension of soot aggregates gradually decrease as the surface growth rates of soot aggregates decrease significantly. However, the effect of increasing Rej on coagulation and nucleation rates are slight due to the decreasing residence time of soot particles in the combustor.