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Impact of Discharge Duration on Lean Combustion in Spark Ignition Engines.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Impact of Discharge Duration on Lean Combustion in Spark Ignition Engines./
Author:	Zhu, Hua.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2021,
Description:	175 p.
Notes:	Source: Dissertations Abstracts International, Volume: 82-12, Section: B.
Contained By:	Dissertations Abstracts International82-12B.
Subject:	Automotive engineering. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28413725
ISBN:	9798505542941

Impact of Discharge Duration on Lean Combustion in Spark Ignition Engines.
Zhu, Hua.

Impact of Discharge Duration on Lean Combustion in Spark Ignition Engines. - Ann Arbor : ProQuest Dissertations & Theses, 2021 - 175 p.

Source: Dissertations Abstracts International, Volume: 82-12, Section: B.

Thesis (Ph.D.)--University of Windsor (Canada), 2021.

This item must not be sold to any third party vendors.

Fuel-lean combustion in spark ignition engines is a promising strategy to improve engine efficiency. However, a fuel lean cylinder charge tends to lower the burning velocity because of the lowered chemical reactivity of the mixture, unless the flame propagation is accelerated by introducing an intensified flow field in the combustion chamber. Nevertheless, the literature reveals that the lean burn strategy with intensified flow fields can impose severe challenges on the ignition and flame development processes both in present and upcoming production engines. To address these issues and to better secure the flame kernel at the initial stage of combustion, various ignition strategies have been proposed with the aim of developing higher discharge current and longer discharge duration in the ignition processes, compared to those encountered with conventional spark ignition techniques. Moreover, while both current amplitude and duration of the plasma channel are fundamental to the flame kernel formation and development, their roles have not been fully clarified, let alone adequately quantified, in respect to the extensive variations in pressure, temperature, flow status, and mixture strength. Consequently, in this study, the impacts of discharge current amplitude and duration on the flame kernel initiation were investigated empirically using a constant volume combustion chamber and a single-cylinder research engine platform. The constant volume combustion chamber system was constructed so that a gas mixture with independently controlled pressure, composition, and flow intensity could be supplied. High-speed imaging was used to enable spatial and temporal characterizations of the flame kernel initiation process. Turbulence was generated inside the combustion chamber by a jet flow setup. A field programmable gate array (FPGA) controller was used to synchronize the controls of the sparking events, jet flow, and high-speed imaging. To achieve independent control of the discharge current amplitude and duration, the discharge current profile was modulated to form a quasi-rectangular shape by using a variety of hardware configurations and event controls. Ignition studies with various discharge current amplitudes and durations were conducted under both quiescent and flow conditions. Combustion test results showed that both discharge current amplitude and discharge duration had minimal impact on the ignition process under quiescent condition. However, under flow conditions, a longer discharge duration contributed to tailing flame kernels near the spark gap, and a higher discharge current amplitude contributed to larger flame kernels. Based on the experimental results and analysis, a correlation between the discharge current profiles and the flame kernel development was established with ultra-lean mixtures under intensified flow conditions. Additionally, the operational principles of the single-coil repetitive discharge and dual-coil offset discharge strategies were explored and explained. The necessary control algorithms for the repetitive and offset discharge strategies were established by analyzing the empirically acquired electrical waveforms of the discharge events. Finally, a preliminary investigation of the impact of discharge duration on the ignition stability was conducted using a single-cylinder research engine fitted with precise coolant conditioning, flexible air and fuel management, and comprehensive measurement and data acquisition. The experimental results indicated that a longer discharge duration contributed to improved combustion stability. However, ignition delay and combustion duration were unaffected by the prolonged discharge duration.

ISBN: 9798505542941Subjects--Topical Terms:

2181195
Automotive engineering.
Subjects--Index Terms:

Discharge current amplitude

Impact of Discharge Duration on Lean Combustion in Spark Ignition Engines.
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245 1 0 $a Impact of Discharge Duration on Lean Combustion in Spark Ignition Engines.
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300 $a 175 p.
500 $a Source: Dissertations Abstracts International, Volume: 82-12, Section: B.
500 $a Advisor: Zheng, M.;Reader, Graham.
502 $a Thesis (Ph.D.)--University of Windsor (Canada), 2021.
506 $a This item must not be sold to any third party vendors.
520 $a Fuel-lean combustion in spark ignition engines is a promising strategy to improve engine efficiency. However, a fuel lean cylinder charge tends to lower the burning velocity because of the lowered chemical reactivity of the mixture, unless the flame propagation is accelerated by introducing an intensified flow field in the combustion chamber. Nevertheless, the literature reveals that the lean burn strategy with intensified flow fields can impose severe challenges on the ignition and flame development processes both in present and upcoming production engines. To address these issues and to better secure the flame kernel at the initial stage of combustion, various ignition strategies have been proposed with the aim of developing higher discharge current and longer discharge duration in the ignition processes, compared to those encountered with conventional spark ignition techniques. Moreover, while both current amplitude and duration of the plasma channel are fundamental to the flame kernel formation and development, their roles have not been fully clarified, let alone adequately quantified, in respect to the extensive variations in pressure, temperature, flow status, and mixture strength. Consequently, in this study, the impacts of discharge current amplitude and duration on the flame kernel initiation were investigated empirically using a constant volume combustion chamber and a single-cylinder research engine platform. The constant volume combustion chamber system was constructed so that a gas mixture with independently controlled pressure, composition, and flow intensity could be supplied. High-speed imaging was used to enable spatial and temporal characterizations of the flame kernel initiation process. Turbulence was generated inside the combustion chamber by a jet flow setup. A field programmable gate array (FPGA) controller was used to synchronize the controls of the sparking events, jet flow, and high-speed imaging. To achieve independent control of the discharge current amplitude and duration, the discharge current profile was modulated to form a quasi-rectangular shape by using a variety of hardware configurations and event controls. Ignition studies with various discharge current amplitudes and durations were conducted under both quiescent and flow conditions. Combustion test results showed that both discharge current amplitude and discharge duration had minimal impact on the ignition process under quiescent condition. However, under flow conditions, a longer discharge duration contributed to tailing flame kernels near the spark gap, and a higher discharge current amplitude contributed to larger flame kernels. Based on the experimental results and analysis, a correlation between the discharge current profiles and the flame kernel development was established with ultra-lean mixtures under intensified flow conditions. Additionally, the operational principles of the single-coil repetitive discharge and dual-coil offset discharge strategies were explored and explained. The necessary control algorithms for the repetitive and offset discharge strategies were established by analyzing the empirically acquired electrical waveforms of the discharge events. Finally, a preliminary investigation of the impact of discharge duration on the ignition stability was conducted using a single-cylinder research engine fitted with precise coolant conditioning, flexible air and fuel management, and comprehensive measurement and data acquisition. The experimental results indicated that a longer discharge duration contributed to improved combustion stability. However, ignition delay and combustion duration were unaffected by the prolonged discharge duration.
590 $a School code: 0115.
650 4 $a Automotive engineering. $3 2181195
650 4 $a Mechanical engineering. $3 649730
653 $a Discharge current amplitude
653 $a Dual-coil offset
653 $a Fuel-lean combustion
653 $a Single-coil repetitive discharge
653 $a Flame kernel formation and development
653 $a Combustion stability
653 $a Plasma channel
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710 2 $a University of Windsor (Canada). $b MECHANICAL ENGINEERING. $3 2093247
773 0 $t Dissertations Abstracts International $g 82-12B.
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791 $a Ph.D.
792 $a 2021
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28413725