Experimental Investigation of Large Scale Aerodynamics on Soot Emissions in Swirling Flows
type: CreativeWork
description: Soot are microscopic airborne particles that impact human health and global climate, and are released into the atmosphere as a result of incomplete combustion. Reducing soot formation from burners improves both their efficiency and emissions standards. Modern burners utilize the Rich-Quench-Lean (RQL) technology that employs turbulent swirling flames with downstream dilution air. These turbulent flames exhibit spatial and temporal fluctuations not present in laminar flames. This adds a level of complexity to turbulent soot studies that is yet to be fully understood. In this study, a comprehensive analysis of soot formation in swirl-stabilized non-premixed turbulent flames at atmospheric pressure is performed using both Ethylene and an alternative Gevo alcohol-to-jet kerosene fuel referred to as Jet C-1. The goal is to extend the understanding presently available in the literature on dilution air by investigating the impact of systematically varying the amount and location of downstream radially injected dilution air on soot formation and oxidation for the first time. Firstly, Cold flow PIV was used to study the flow field and data revealed an increase in velocities and turbulence within the central recirculation zone (CRZ) as a result of dilution air. The impact of the dilution jets shifts downstream leaving the CRZ and shear layer unaltered as they are moved farther downstream, making them less effective, even if the dilution momentum through them is increased. Next, OH-PLIF, PAH-PLIF and soot LII experiments were used to study the Ethylene flames. Past work has looked at dilution jets positioned at a fixed downstream location. In this thesis, the location and amount of dilution air were systematically varied. Results revealed a strong correlation between OH, PAH and soot distributions, which are affected by the location of the dilution jets relative to the CRZ, where soot primarily forms. Dilution jets positioned up to two bluff body diameters from the burner inle…
abstract: Soot are microscopic airborne particles that impact human health and global climate, and are released into the atmosphere as a result of incomplete combustion. Reducing soot formation from burners improves both their efficiency and emissions standards. Modern burners utilize the Rich-Quench-Lean (RQL) technology that employs turbulent swirling flames with downstream dilution air. These turbulent flames exhibit spatial and temporal fluctuations not present in laminar flames. This adds a level of complexity to turbulent soot studies that is yet to be fully understood. In this study, a comprehensive analysis of soot formation in swirl-stabilized non-premixed turbulent flames at atmospheric pressure is performed using both Ethylene and an alternative Gevo alcohol-to-jet kerosene fuel referred to as Jet C-1. The goal is to extend the understanding presently available in the literature on dilution air by investigating the impact of systematically varying the amount and location of downstream radially injected dilution air on soot formation and oxidation for the first time. Firstly, Cold flow PIV was used to study the flow field and data revealed an increase in velocities and turbulence within the central recirculation zone (CRZ) as a result of dilution air. The impact of the dilution jets shifts downstream leaving the CRZ and shear layer unaltered as they are moved farther downstream, making them less effective, even if the dilution momentum through them is increased. Next, OH-PLIF, PAH-PLIF and soot LII experiments were used to study the Ethylene flames. Past work has looked at dilution jets positioned at a fixed downstream location. In this thesis, the location and amount of dilution air were systematically varied. Results revealed a strong correlation between OH, PAH and soot distributions, which are affected by the location of the dilution jets relative to the CRZ, where soot primarily forms. Dilution jets positioned up to two bluff body diameters from the burner inle…
author: El Helou, Ingrid
language: eng
keywords: Turbulent swirling flames, LII, Particle Size Distributions, Soot from an alternative jet fuel, Soot Volume Fraction, Soot oxidation, RQL combustor
license: https://www.repository.cam.ac.uk/bitstreams/342b7e8c-ba76-422a-8d43-1389ccb4b5e6/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2021-02-01
date modified: 2026-07-24T01:33:18Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.73730