On the Use of Laser-Induced Incandescence for Soot Diagnostics: From Theoretical Aspects to Applications in Engines
type: CreativeWork
description: The laser-induced incandescence technique (LII) is a laser-based diagnostic technique for measurements of soot volume fraction and particle size. The technique relies on detection of incandescent light from soot particles heated to around 4000 K using nanosecond laser pulses. A theoretical model for LII has been implemented and improved in order to provide a tool for predicting the signal response from soot particles when exposed to the laser pulse for various experimental conditions. Specifically, the model is capable of predicting the signal response from arbitrarily shaped measurement volumes defined by non-uniform spatial distribution of laser energy, and also from primary particle size distributions. The model has been applied in order to investigate the influence of various physical and experimental parameters on evaluated primary particle size, the uncertainties introduced when measuring quantitative soot volume fractions in high-pressure environments using atmospheric calibration flames and on the relationship between the LII signal and the soot volume fraction. The model has also been applied in order to predict the appearance of experimentally obtained spatially resolved LII signals in a methane diffusion flame. The spatial distribution of laser energy, which has a profound influence on the LII signal behaviour, was measured using a beam profile CCD camera, the data being input to the model. A generally good agreement between theoretical and experimental data was found, but the results indicated that the theoretical model overpredicted the signal response at high fluence. Two experimental investigations using laser diagnostics for in-cylinder measurements of internal combustion engines have been undertaken. In one of the studies the laser-induced fluorescence (LIF) technique was applied to measure the flame propagation inside a spark-ignition engine by detection of fluorescence from intermediate species in the end gas. Two Nd:YAG lasers operating at 355 nm…
abstract: The laser-induced incandescence technique (LII) is a laser-based diagnostic technique for measurements of soot volume fraction and particle size. The technique relies on detection of incandescent light from soot particles heated to around 4000 K using nanosecond laser pulses. A theoretical model for LII has been implemented and improved in order to provide a tool for predicting the signal response from soot particles when exposed to the laser pulse for various experimental conditions. Specifically, the model is capable of predicting the signal response from arbitrarily shaped measurement volumes defined by non-uniform spatial distribution of laser energy, and also from primary particle size distributions. The model has been applied in order to investigate the influence of various physical and experimental parameters on evaluated primary particle size, the uncertainties introduced when measuring quantitative soot volume fractions in high-pressure environments using atmospheric calibration flames and on the relationship between the LII signal and the soot volume fraction. The model has also been applied in order to predict the appearance of experimentally obtained spatially resolved LII signals in a methane diffusion flame. The spatial distribution of laser energy, which has a profound influence on the LII signal behaviour, was measured using a beam profile CCD camera, the data being input to the model. A generally good agreement between theoretical and experimental data was found, but the results indicated that the theoretical model overpredicted the signal response at high fluence. Two experimental investigations using laser diagnostics for in-cylinder measurements of internal combustion engines have been undertaken. In one of the studies the laser-induced fluorescence (LIF) technique was applied to measure the flame propagation inside a spark-ignition engine by detection of fluorescence from intermediate species in the end gas. Two Nd:YAG lasers operating at 355 nm…
author: Bladh, Henrik
language: eng
keywords: Atom and Molecular Physics and Optics, Laser-Induced Incandescence, Laser Diagnostics, LII, Soot, Model, Engine, Particulates, Soot volume fraction, Combustion, Physics, Fysik, quantum mechanics, classical mechanics, Mathematical and general theoretical physics, Matematisk och allmän teoretisk fysik, thermodynamics, statistical physics, gravitation, relativity, kvantmekanik, klassisk mekanik, termodynamik, statistisk fysik, relativitet, Gases, Gaser, fluid dynamics, plasmas, Teknik, Laserteknik, Motors and propulsion systems, Motorer, framdrivningssystem, fluiddynamik, plasma, Technological sciences, Laser technology
identifier: other:ISRN: LUTFD2/TFCP--07/119--SE
date published: 2007
date modified: 2026-07-24T03:00:02Z
provider: University of Lund
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Avdelningen för Förbränningsfysik, Fysiska Institutionen, Lunds Tekniska Högskola