A computational study of soot formation and flame structure of coflow laminar methane/air diffusion flames under microgravity and normal gravity

Abstract

A computational study of soot formation and flame structure of coflow laminar methane/air diffusion flames under microgravity and normal gravityA numerical study is conducted of methane-air coflow diffusion flames at microgravity (µg) and normal gravity (1g), and comparisons are made with experimental data in the literature. The model employed uses a detailed gas phase chemical kinetic mechanism that includes PAH formation and growth, and is coupled to a sectional soot particle dynamics model. The model is able to accurately predict the trends observed experimentally with reduction of gravity without any tuning of the model for different flames. The microgravity sooting flames were found to have lower temperatures and higher volume fraction than their normal gravity counterparts. In the absence of gravity, the flame radii increase due to elimination of buoyance forces and reduction of flow velocity, which is consistent with experimental observations. Soot formation along the wings is seen to be surface growth dominated, while PAH condensation plays a more major role on centerline soot formation. Surface growth and PAH growth increase in microgravity primarily due to increases in the residence time inside the flame. The rate of increase of surface growth is more significant compared to PAH growth, which causes soot distribution to shift from the centerline of the flame to the wings in microgravity.

An Artificial Neural Network for the Low-Cost Prediction of Soot Emissions

“…In the present work, the input/output datasets are obtained from the CoFlame code [12]. CoFlame has been used extensively by multiple research groups to study a wide variety of axisymmetric laminar diffusion flames including those at microgravity and high pressure [40][41][42]. It is worth mentioning that CoFlame solves for soot primary particle number density and soot aggregate number density equations in addition to the conservation equations for mass, momentum, energy, and species mass [12].…”

Development of a soot concentration estimation library for industrial combustion applications using Lagrangian parcel tracking

“…Many of the works studied have implemented the sectional method to model soot formation and kinetics [26][27][28][29][30][31][32][33][34][35]. While these works have focused on atmospheric pressure flames, recently studies on modelling soot at elevated pressures [36,37] and micro-gravity have been conducted as well [38].…”

Pinch-off process of Burke–Schumann flame under acoustic excitation

“…In particular, a significant decrease in the NOx concentration was observed in the resonance frequency of the flame. These pollutant studies were conducted not only in laminar flames [12][13][14][15] but also in turbulent flames [16][17][18], and upon considering the effects of increasing pressure [19][20][21]. The pinch-off flame tip is the main factor contributing to the generation of the pollutant [22], and the residence time of the pocket flame separated from the main flame is longer than that of other normal flames.…”