Laser-based Optical Diagnostics of Electrode Wear : A Pioneering Work
(2025)- Abstract
- Improving spark-ignition engines in terms of efficiency and compatibility with renewable fuels is essential for ensuring energy security, cost-effectiveness, and sustainability. However, electrode wear of spark plugs, especially under conditions involving novel fuels and lean mixtures, becomes a significant technical challenge. Therefore, a deeper understanding of the interactions between spark discharges and electrode materials is more crucial than ever.
Conventional ex-situ, long-term testing methods lack the temporal and spatial resolution required to capture the dynamics of electrode wear during short spark discharges. As a pioneering work, this thesis incorporates laser-based optical diagnostics to study electrode wear of... (More) - Improving spark-ignition engines in terms of efficiency and compatibility with renewable fuels is essential for ensuring energy security, cost-effectiveness, and sustainability. However, electrode wear of spark plugs, especially under conditions involving novel fuels and lean mixtures, becomes a significant technical challenge. Therefore, a deeper understanding of the interactions between spark discharges and electrode materials is more crucial than ever.
Conventional ex-situ, long-term testing methods lack the temporal and spatial resolution required to capture the dynamics of electrode wear during short spark discharges. As a pioneering work, this thesis incorporates laser-based optical diagnostics to study electrode wear of spark plugs in-situ for the first time.
Strong nickel emission lines were detected between two prominent nitrogen bands during spark discharges. Several excitation pathways of nickel atoms were investigated, identifying the 336.96 nm line as the optimal transition for diagnostic purposes. The effective fluorescence lifetime of nickel under atmospheric conditions was measured for the first time and found to be approximately 1.1 ns, with no statistically significant variation throughout the discharge duration. The spatiotemporal behavior of gas-phase nickel atoms originating from the spark plug electrodes was characterized using planar laser-induced fluorescence. The spatial distribution of nickel atoms across the electrode gap varied with pressure, indicating different wear mechanisms. Spark power was identified as the dominant factor driving electrode erosion via evaporation, and a classic model was modified accordingly.
Overall, this thesis provides valuable experimental data and offers new insights into the fundamental mechanisms governing spark discharge-electrode interactions, contributing to the advancement of ignition systems for future spark ignition internal combustion engines. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/45263833-8503-4bcd-a147-ed1fb31b0c30
- author
- Zhang, Kailun LU
- supervisor
-
- Mattias Richter LU
- Andreas Ehn LU
- opponent
-
- Assoc. Prof. Burns, Iain, Strathclyde University, United Kingdom.
- organization
- publishing date
- 2025-08-19
- type
- Thesis
- publication status
- published
- subject
- keywords
- Spark Discharge, Electrode Wear, Laser Diagnostics, Optical Emission Spectroscopy, Laser-induced Fluorescence, Spark Plug, Nickel
- pages
- 94 pages
- publisher
- Division of Combustion Physics, Department of Physics, Lund University
- defense location
- Lecture Hall Rydbergsalen, Department of Physics, Professorsgatan 1, Faculty of Engineering LTH, Lund University, Lund.
- defense date
- 2025-09-12 09:15:00
- ISBN
- 978-91-8104-507-9
- 978-91-8104-508-6
- project
- Tändstiftslitage i biobränsleapplikationer
- language
- English
- LU publication?
- yes
- id
- 45263833-8503-4bcd-a147-ed1fb31b0c30
- date added to LUP
- 2025-08-18 19:21:20
- date last changed
- 2025-08-19 13:33:11
@phdthesis{45263833-8503-4bcd-a147-ed1fb31b0c30,
abstract = {{Improving spark-ignition engines in terms of efficiency and compatibility with renewable fuels is essential for ensuring energy security, cost-effectiveness, and sustainability. However, electrode wear of spark plugs, especially under conditions involving novel fuels and lean mixtures, becomes a significant technical challenge. Therefore, a deeper understanding of the interactions between spark discharges and electrode materials is more crucial than ever.<br/><br/>Conventional ex-situ, long-term testing methods lack the temporal and spatial resolution required to capture the dynamics of electrode wear during short spark discharges. As a pioneering work, this thesis incorporates laser-based optical diagnostics to study electrode wear of spark plugs in-situ for the first time.<br/><br/>Strong nickel emission lines were detected between two prominent nitrogen bands during spark discharges. Several excitation pathways of nickel atoms were investigated, identifying the 336.96 nm line as the optimal transition for diagnostic purposes. The effective fluorescence lifetime of nickel under atmospheric conditions was measured for the first time and found to be approximately 1.1 ns, with no statistically significant variation throughout the discharge duration. The spatiotemporal behavior of gas-phase nickel atoms originating from the spark plug electrodes was characterized using planar laser-induced fluorescence. The spatial distribution of nickel atoms across the electrode gap varied with pressure, indicating different wear mechanisms. Spark power was identified as the dominant factor driving electrode erosion via evaporation, and a classic model was modified accordingly.<br/><br/>Overall, this thesis provides valuable experimental data and offers new insights into the fundamental mechanisms governing spark discharge-electrode interactions, contributing to the advancement of ignition systems for future spark ignition internal combustion engines.}},
author = {{Zhang, Kailun}},
isbn = {{978-91-8104-507-9}},
keywords = {{Spark Discharge; Electrode Wear; Laser Diagnostics; Optical Emission Spectroscopy; Laser-induced Fluorescence; Spark Plug; Nickel}},
language = {{eng}},
month = {{08}},
publisher = {{Division of Combustion Physics, Department of Physics, Lund University}},
school = {{Lund University}},
title = {{Laser-based Optical Diagnostics of Electrode Wear : A Pioneering Work}},
url = {{https://lup.lub.lu.se/search/files/225603075/Kl_Zhang_Thesis_Web.pdf}},
year = {{2025}},
}