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UBC Theses and Dissertations
Spark ignition of partially stratified gaseous fuel-air mixtures Chan, Edward C.
Abstract
The Partially Stratified Charge (PSC) strategy aims to stabilize the spark ignition of lean-burn natural gas fueled internal combustion engines. This results in an extension of unthrottled load control, as well as a reduction in regulated pollutant and carbon dioxide emissions. While engine experiments demonstrated the feasibility of this technology, its fundamental enabling mechanisms have yet to be identified. An experimental / numerical approach was taken for the current investigation, using an idealized PSC ignition system. The PSC injection took place in a constant volume combustion chamber (CVCC) into an initially quiescent bulk mixture. A customized injection system was also developed. Experimental results indicated that stable combustion could be achieved with PSC at an air-to-fuel ratio of λ = 2.0. Furthermore, the use of double PSC injection facilitated additional consumption of the bulk fuel. The experiments also identified three primary enabling mechanisms under which PSC assists in ultra-lean spark ignited combustion. Additional insights were provided through numerical modeling. The PSC jet was modeled using the standard k−epsilon model and was found to be in excellent agreement with the experimental results in terms of penetration and entrainment. Meanwhile, the Eddy Dissipation Concept (EDC) model was used to simulate the combustion under PSC. While the computational model lacked the ability to properly predict combustion rates in the turbulent-to-laminar flame transition, the ignition and early combustion phases were properly captured. The numerical framework was applied to engine conditions, and the modeled data were validated using existing experimental results. A semi-analytical ignition model was developed using detailed chemical kinetic mechanisms. A turbulent ignition parameter was derived accordingly to characterize the likelihood of an ignition event leading to combustion. The engine simulation results also provided further information in PSC charge formation, as well as flame propagation. The results of this research gave rise to an improved design for future generation PSC injection / ignition devices.
Item Metadata
Title |
Spark ignition of partially stratified gaseous fuel-air mixtures
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2010
|
Description |
The Partially Stratified Charge (PSC) strategy aims to stabilize the spark ignition of lean-burn
natural gas fueled internal combustion engines. This results in an extension of unthrottled
load control, as well as a reduction in regulated pollutant and carbon dioxide emissions. While
engine experiments demonstrated the feasibility of this technology, its fundamental enabling
mechanisms have yet to be identified.
An experimental / numerical approach was taken for the current investigation, using an
idealized PSC ignition system. The PSC injection took place in a constant volume combustion
chamber (CVCC) into an initially quiescent bulk mixture. A customized injection system was
also developed. Experimental results indicated that stable combustion could be achieved with
PSC at an air-to-fuel ratio of λ = 2.0. Furthermore, the use of double PSC injection facilitated additional consumption of the bulk fuel. The experiments also identified three primary enabling
mechanisms under which PSC assists in ultra-lean spark ignited combustion.
Additional insights were provided through numerical modeling. The PSC jet was modeled
using the standard k−epsilon model and was found to be in excellent agreement with the experimental results in terms of penetration and entrainment. Meanwhile, the Eddy Dissipation Concept
(EDC) model was used to simulate the combustion under PSC. While the computational model
lacked the ability to properly predict combustion rates in the turbulent-to-laminar flame transition, the ignition and early combustion phases were properly captured.
The numerical framework was applied to engine conditions, and the modeled data were
validated using existing experimental results. A semi-analytical ignition model was developed
using detailed chemical kinetic mechanisms. A turbulent ignition parameter was derived
accordingly to characterize the likelihood of an ignition event leading to combustion. The
engine simulation results also provided further information in PSC charge formation, as well
as flame propagation. The results of this research gave rise to an improved design for future
generation PSC injection / ignition devices.
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Genre | |
Type | |
Language |
eng
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Date Available |
2010-10-26
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivs 3.0 Unported
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DOI |
10.14288/1.0071412
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2010-11
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Campus | |
Scholarly Level |
Graduate
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Rights URI | |
Aggregated Source Repository |
DSpace
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Rights
Attribution-NonCommercial-NoDerivs 3.0 Unported