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An experimental and modeling-based study into the ignition delay characteristics of diesel surrogate binary blend fuels / Matthew A. Carr in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 134 N° 7 (Juillet 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 7 (Juillet 2012) . - 10 p. Titre : An experimental and modeling-based study into the ignition delay characteristics of diesel surrogate binary blend fuels Type de document : texte imprimé Auteurs : Matthew A. Carr, Auteur ; Caton, Patrick A., Auteur ; Leonard J. Hamilton, Auteur Année de publication : 2012 Article en page(s) : 10 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Ignition  delay  Combustion  characteristics  Diesel  fuels  Single-cylinder  research  engine  Homogeneous  reactor  model  Binary  blend  fuels Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This study examines the combustion characteristics of a binary mixture surrogate for possible future diesel fuels using both a single-cylinder research engine and a homogeneous reactor model using detailed chemical reaction kinetics. Binary mixtures of a normal straight-chain alkane (pure n-hexadecane, also known as n-cetane, C16H34) and an alkyl aromatic (toluene, C7H8) were tested in a single-cylinder research engine. Pure n-hexadecane was tested as a baseline reference, followed by 50%, 70%, and 80% toluene in hexadecane blends. Testing was conducted at fixed engine speed and constant indicated load. As references, two conventional petroleum-based fuels (commercial diesel and U.S. Navy JP-5 jet fuel) and five synthetic Fischer-Tropsch-based fuels were also tested. The ignition delay of the binary mixture surrogate increased with increasing toluene fraction and ranged from approximately 1.3 ms (pure hexadecane) to 3.0 ms (80% toluene in hexadecane). While ignition delay changed substantially, the location of 50% mass fraction burned did not change as significantly due to a simultaneous change in the premixed combustion fraction. Detailed chemical reaction rate modeling using a constant pressure, adiabatic, homogeneous reactor model predicts a chemical ignition delay with a similar trend to the experimental results but shorter overall magnitude. The difference between this predicted homogeneous chemical ignition delay and the experimentally observed ignition delay is defined as the physical ignition delay due to processes such as spray formation, entrainment, mixing, and vaporization. On a relative basis, the addition of 70% toluene to hexadecane causes a nearly identical relative increase in both physical and chemical ignition delay of approximately 50%. The chemical kinetic model predicts that, even though the addition of toluene delays the global onset of ignition, the initial production of reactive precursors such as HO2 and H2O2 may be faster with toluene due to the weakly bound methyl group. However, this initial production is insufficient to lead to wide-scale chain branching and ignition. The model predicts that the straight-chain alkane component (hexadecane) ignites first, causing the aromatic component to be consumed shortly thereafter. Greater ignition delay observed with the high toluene fraction blends is due to consumption of OH radicals by toluene. Overall, the detailed kinetic model captures the experimentally observed trends well and may be able to provide insight as to the relationship between bulk properties and physical ignition delay. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000007 [...] [article] An experimental and modeling-based study into the ignition delay characteristics of diesel surrogate binary blend fuels [texte imprimé] / Matthew A. Carr, Auteur ; Caton, Patrick A., Auteur ; Leonard J. Hamilton, Auteur . - 2012 . - 10 p. Génie mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 7 (Juillet 2012) . - 10 p. Mots-clés : Ignition  delay  Combustion  characteristics  Diesel  fuels  Single-cylinder  research  engine  Homogeneous  reactor  model  Binary  blend  fuels Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This study examines the combustion characteristics of a binary mixture surrogate for possible future diesel fuels using both a single-cylinder research engine and a homogeneous reactor model using detailed chemical reaction kinetics. Binary mixtures of a normal straight-chain alkane (pure n-hexadecane, also known as n-cetane, C16H34) and an alkyl aromatic (toluene, C7H8) were tested in a single-cylinder research engine. Pure n-hexadecane was tested as a baseline reference, followed by 50%, 70%, and 80% toluene in hexadecane blends. Testing was conducted at fixed engine speed and constant indicated load. As references, two conventional petroleum-based fuels (commercial diesel and U.S. Navy JP-5 jet fuel) and five synthetic Fischer-Tropsch-based fuels were also tested. The ignition delay of the binary mixture surrogate increased with increasing toluene fraction and ranged from approximately 1.3 ms (pure hexadecane) to 3.0 ms (80% toluene in hexadecane). While ignition delay changed substantially, the location of 50% mass fraction burned did not change as significantly due to a simultaneous change in the premixed combustion fraction. Detailed chemical reaction rate modeling using a constant pressure, adiabatic, homogeneous reactor model predicts a chemical ignition delay with a similar trend to the experimental results but shorter overall magnitude. The difference between this predicted homogeneous chemical ignition delay and the experimentally observed ignition delay is defined as the physical ignition delay due to processes such as spray formation, entrainment, mixing, and vaporization. On a relative basis, the addition of 70% toluene to hexadecane causes a nearly identical relative increase in both physical and chemical ignition delay of approximately 50%. The chemical kinetic model predicts that, even though the addition of toluene delays the global onset of ignition, the initial production of reactive precursors such as HO2 and H2O2 may be faster with toluene due to the weakly bound methyl group. However, this initial production is insufficient to lead to wide-scale chain branching and ignition. The model predicts that the straight-chain alkane component (hexadecane) ignites first, causing the aromatic component to be consumed shortly thereafter. Greater ignition delay observed with the high toluene fraction blends is due to consumption of OH radicals by toluene. Overall, the detailed kinetic model captures the experimentally observed trends well and may be able to provide insight as to the relationship between bulk properties and physical ignition delay. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000007 [...]

The effects of intake plenum volume on the performance of a small naturally aspirated restricted engine / Leonard J. Hamilton in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 1 (Janvier 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 1 (Janvier 2011) . - 07 p. Titre : The effects of intake plenum volume on the performance of a small naturally aspirated restricted engine Type de document : texte imprimé Auteurs : Leonard J. Hamilton, Auteur ; Jim S. Cowart, Auteur ; Jasen E. Lee, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Automotive  engineering  Intake  systems  (machines)  Internal  combustion  engines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Intake tuning is a widely recognized method for optimizing the performance of a naturally aspirated engine for motorsports applications. Wave resonance and Helmholtz theories are useful for predicting the impact of intake runner length on engine performance. However, there is very little information in the literature regarding the effects of intake plenum volume. The goal of this study was to determine the effects of intake plenum volume on steady state and transient engine performance for a restricted naturally aspirated engine for Formula Society of Automotive Engineers (FSAE) vehicle use. Testing was conducted on a four cylinder 600 cc motorcycle engine fitted with a 20 mm restrictor in compliance with FSAE competition rules. Plenum sizes were varied from 2 to 10 times engine displacement (1.2–6.0 l) and engine speeds were varied from 3000 rpm to 12,500 rpm. Performance metrics including volumetric efficiency, torque, and power were recorded at steady state conditions. Experimental results showed that engine performance increased modestly as plenum volume was increased from 2 to 8 times engine displacement (4.8 l). Increasing plenum volume beyond 4.8 l resulted in significant improvement in performance parameters. Overall, peak power was shown to increase from 54 kW to 63 kW over the range of plenums tested. Additionally, transient engine performance was evaluated using extremely fast (60 ms) throttle opening times for the full range of plenum sizes tested. In-cylinder pressure was used to calculate cycle-resolved gross indicated mean effective pressure (IMEPg) development during these transients. Interestingly, the cases with the largest plenum sizes only took 1 to 2 extra cycles (30–60 ms) to achieve maximum IMEPg levels when compared with the smaller volumes. In fact, the differences were so minor that it would be doubtful that a driver would notice the lag. Additional metrics included time for the plenums to fill and an analysis of manifold absolute pressure and peak in-cylinder pressure development during and after the throttle transient. Plenums below 4.8 l completely filled even before the transient was completed. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] The effects of intake plenum volume on the performance of a small naturally aspirated restricted engine [texte imprimé] / Leonard J. Hamilton, Auteur ; Jim S. Cowart, Auteur ; Jasen E. Lee, Auteur . - 2012 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 1 (Janvier 2011) . - 07 p. Mots-clés : Automotive  engineering  Intake  systems  (machines)  Internal  combustion  engines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Intake tuning is a widely recognized method for optimizing the performance of a naturally aspirated engine for motorsports applications. Wave resonance and Helmholtz theories are useful for predicting the impact of intake runner length on engine performance. However, there is very little information in the literature regarding the effects of intake plenum volume. The goal of this study was to determine the effects of intake plenum volume on steady state and transient engine performance for a restricted naturally aspirated engine for Formula Society of Automotive Engineers (FSAE) vehicle use. Testing was conducted on a four cylinder 600 cc motorcycle engine fitted with a 20 mm restrictor in compliance with FSAE competition rules. Plenum sizes were varied from 2 to 10 times engine displacement (1.2–6.0 l) and engine speeds were varied from 3000 rpm to 12,500 rpm. Performance metrics including volumetric efficiency, torque, and power were recorded at steady state conditions. Experimental results showed that engine performance increased modestly as plenum volume was increased from 2 to 8 times engine displacement (4.8 l). Increasing plenum volume beyond 4.8 l resulted in significant improvement in performance parameters. Overall, peak power was shown to increase from 54 kW to 63 kW over the range of plenums tested. Additionally, transient engine performance was evaluated using extremely fast (60 ms) throttle opening times for the full range of plenum sizes tested. In-cylinder pressure was used to calculate cycle-resolved gross indicated mean effective pressure (IMEPg) development during these transients. Interestingly, the cases with the largest plenum sizes only took 1 to 2 extra cycles (30–60 ms) to achieve maximum IMEPg levels when compared with the smaller volumes. In fact, the differences were so minor that it would be doubtful that a driver would notice the lag. Additional metrics included time for the plenums to fill and an analysis of manifold absolute pressure and peak in-cylinder pressure development during and after the throttle transient. Plenums below 4.8 l completely filled even before the transient was completed. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Understanding ignition delay effects with pure component fuels in a single-cylinder diesel engine / Caton, Patrick A. in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 11 p. Titre : Understanding ignition delay effects with pure component fuels in a single-cylinder diesel engine Type de document : texte imprimé Auteurs : Caton, Patrick A., Auteur ; Leonard J. Hamilton, Auteur ; Jim S. Cowart, Auteur Année de publication : 2012 Article en page(s) : 11 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Diesel  engines  Ignition  Surface  tension  Viscosity Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In order to better understand how future candidate diesel fuels may affect combustion characteristics in diesel engines, 21 pure component hydrocarbon fuels were tested in a single-cylinder diesel engine. These pure component fuels included normal alkanes (C6–C16), normal primary alkenes (C6–C18), isoalkanes, cycloalkanes/-enes, and aromatic species. In addition, seven fuel blends were tested, including commercial diesel fuel, U.S. Navy JP-5 aviation fuel, and five Fischer–Tropsch synthetic fuels. Ignition delay was used as a primary combustion metric for each fuel, and the ignition delay period was analyzed from the perspective of the physical delay period followed by the chemical delay period. While fuel properties could not strictly be varied independently of each other, several ignition delay correlations with respect to physical properties were suggested. In general, longer ignition delays were observed for component fuels with lower liquid fuel density, kinematic viscosity, and liquid-air surface tension. Longer ignition delay was also observed for component fuels with higher fuel volatility, as measured by boiling point and vapor pressure. Experimental data show two regimes of operation: For a carbon chain length of 12 or greater, there is little variation in ignition delay for the tested fuels. For shorter chain lengths, a fuel molecular structure is very important. Carbon chain length was used as a scaling variable with an empirical factor to collapse the ignition delay onto a single trend line. Companion detailed kinetic modeling was pursued on the lightest fuel species set (C6) since this fuel set possessed the greatest ignition delay differences. The kinetic model gives a chemical ignition delay time, which, together with the measured experimental ignition delay, suggests that the physical and chemical delay period have comparable importance. However, the calculated chemical delay periods capture the general variation in the overall ignition delay and could be used to predict the ignition delay of possible future synthetic diesel fuels. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Understanding ignition delay effects with pure component fuels in a single-cylinder diesel engine [texte imprimé] / Caton, Patrick A., Auteur ; Leonard J. Hamilton, Auteur ; Jim S. Cowart, Auteur . - 2012 . - 11 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 11 p. Mots-clés : Diesel  engines  Ignition  Surface  tension  Viscosity Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In order to better understand how future candidate diesel fuels may affect combustion characteristics in diesel engines, 21 pure component hydrocarbon fuels were tested in a single-cylinder diesel engine. These pure component fuels included normal alkanes (C6–C16), normal primary alkenes (C6–C18), isoalkanes, cycloalkanes/-enes, and aromatic species. In addition, seven fuel blends were tested, including commercial diesel fuel, U.S. Navy JP-5 aviation fuel, and five Fischer–Tropsch synthetic fuels. Ignition delay was used as a primary combustion metric for each fuel, and the ignition delay period was analyzed from the perspective of the physical delay period followed by the chemical delay period. While fuel properties could not strictly be varied independently of each other, several ignition delay correlations with respect to physical properties were suggested. In general, longer ignition delays were observed for component fuels with lower liquid fuel density, kinematic viscosity, and liquid-air surface tension. Longer ignition delay was also observed for component fuels with higher fuel volatility, as measured by boiling point and vapor pressure. Experimental data show two regimes of operation: For a carbon chain length of 12 or greater, there is little variation in ignition delay for the tested fuels. For shorter chain lengths, a fuel molecular structure is very important. Carbon chain length was used as a scaling variable with an empirical factor to collapse the ignition delay onto a single trend line. Companion detailed kinetic modeling was pursued on the lightest fuel species set (C6) since this fuel set possessed the greatest ignition delay differences. The kinetic model gives a chemical ignition delay time, which, together with the measured experimental ignition delay, suggests that the physical and chemical delay period have comparable importance. However, the calculated chemical delay periods capture the general variation in the overall ignition delay and could be used to predict the ignition delay of possible future synthetic diesel fuels. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]