Documents disponibles écrits par cet auteur

Dynamic Modeling of Residual-Affected Homogeneous Charge Compression Ignition Engines with Variable Valve Actuation / Shaver, Gregory. M. in Transactions of the ASME . Journal of dynamic systems, measurement, and control, Vol. 127, N° 3 (Septembre 2005) 

Public ISBD [article]  in Transactions of the ASME . Journal of dynamic systems, measurement, and control > Vol. 127, N° 3 (Septembre 2005) . - 374-381 p. Titre : Dynamic Modeling of Residual-Affected Homogeneous Charge Compression Ignition Engines with Variable Valve Actuation Titre original : Modèle Dynamique des Moteurs Homogènes Affectés d'Allumage Spontané de Charge de Résiduel avec la Mise en Action Variable de Valve Type de document : texte imprimé Auteurs : Shaver, Gregory. M., Auteur ; Edwards, Christopher F. ; Caton, Patrick A. ; Roelle, Matthew, J. ; Gerdes, J. Christian, Auteur Article en page(s) : 374-381 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Allumage  spontané  homogène  Moteur  à  combustion  Controleur  Cinétique  chimique  Masse  de  commande  Echappement  Propane Index. décimale : 620.1/389 Résumé : One practical method for achieving homogeneous charge compression ignition (HCCI) in internal combustion engines is to modulate the valve to trup or reinduct exhaust gases, increasing the energy of the charge, and enabling autoignition. Controlling combustion phacing with valve modulation can be challenging, however, since any controller must operate through the chemical kinetics of HCCI and account for the cycle to cycle dynamics arising from the retained exhaust gas. This paper presents a simple model of the overall HCCI process that captures these fondamental aspects. The model uses and integrated Arrhenius rate expression to capture the importance of species concentrations and temperature on the ignition process and predict the start of combustion. The cycle to cycle dynamics, in turn, develop through mass exchange between a control volume representing the cylinderand a control mass modeling the exhaust manifold. Despite its simplicity, the model predicts combustion phasing, pressure evolution and work output for propane combustion experiments at levels of fidelity comparable to more complex representations. Transient responses to valve timing changes are also captured and, with minor modification, the model can, in principle, be extended to handle a variety of fuels. Une méthode pratique pour réaliser l'allumage spontané homogène de charge (HCCI) dans des moteurs à combustion interne est de moduler la valve aux gaz d'échappement de trup ou de reinduct, augmentant l'énergie de la charge, et permettant l'auto-allumage. La combustion de contrôle phacing avec la modulation de valve peut être provocante, cependant, puisque n'importe quel contrôleur doit fonctionner par la cinétique chimique de HCCI et expliquer le cycle pour faire un cycle la dynamique résultant du gaz d'échappement maintenu. Cet article présente un modèle simple du processus global de HCCI qui capture ces aspects fondamental. Les utilisations de modèle et l'expression intégrée de taux d'Arrhenius de capturer l'importance des concentrations et de la température d'espèces sur le procédé d'allumage et de prévoir le début de la combustion. Le cycle pour faire un cycle la dynamique, à leur tour, se développent par l'échange de masse entre un volume de commande représentant le cylindre et une masse de commande modelant la tubulure d'échappement. En dépit de sa simplicité, le modèle prévoit la combustion mettant en phase, pressurise l'évolution et fonctionne le rendement pour des expériences de combustion de propane aux niveaux de la fidélité comparables à des représentations plus complexes. Des réponses passagères aux changements de synchronisation de valve sont également capturées et, avec la modification mineure, le modèle peut, en principe, être prolongé pour manipuler une variété de carburants. En ligne : greg.shaver@gmail.com, gerdes@stanford.edu, roelle@stanford.edu, caton@stanford. [...] [article] Dynamic Modeling of Residual-Affected Homogeneous Charge Compression Ignition Engines with Variable Valve Actuation = Modèle Dynamique des Moteurs Homogènes Affectés d'Allumage Spontané de Charge de Résiduel avec la Mise en Action Variable de Valve [texte imprimé] / Shaver, Gregory. M., Auteur ; Edwards, Christopher F. ; Caton, Patrick A. ; Roelle, Matthew, J. ; Gerdes, J. Christian, Auteur . - 374-381 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of dynamic systems, measurement, and control > Vol. 127, N° 3 (Septembre 2005) . - 374-381 p. Mots-clés : Allumage  spontané  homogène  Moteur  à  combustion  Controleur  Cinétique  chimique  Masse  de  commande  Echappement  Propane Index. décimale : 620.1/389 Résumé : One practical method for achieving homogeneous charge compression ignition (HCCI) in internal combustion engines is to modulate the valve to trup or reinduct exhaust gases, increasing the energy of the charge, and enabling autoignition. Controlling combustion phacing with valve modulation can be challenging, however, since any controller must operate through the chemical kinetics of HCCI and account for the cycle to cycle dynamics arising from the retained exhaust gas. This paper presents a simple model of the overall HCCI process that captures these fondamental aspects. The model uses and integrated Arrhenius rate expression to capture the importance of species concentrations and temperature on the ignition process and predict the start of combustion. The cycle to cycle dynamics, in turn, develop through mass exchange between a control volume representing the cylinderand a control mass modeling the exhaust manifold. Despite its simplicity, the model predicts combustion phasing, pressure evolution and work output for propane combustion experiments at levels of fidelity comparable to more complex representations. Transient responses to valve timing changes are also captured and, with minor modification, the model can, in principle, be extended to handle a variety of fuels. Une méthode pratique pour réaliser l'allumage spontané homogène de charge (HCCI) dans des moteurs à combustion interne est de moduler la valve aux gaz d'échappement de trup ou de reinduct, augmentant l'énergie de la charge, et permettant l'auto-allumage. La combustion de contrôle phacing avec la modulation de valve peut être provocante, cependant, puisque n'importe quel contrôleur doit fonctionner par la cinétique chimique de HCCI et expliquer le cycle pour faire un cycle la dynamique résultant du gaz d'échappement maintenu. Cet article présente un modèle simple du processus global de HCCI qui capture ces aspects fondamental. Les utilisations de modèle et l'expression intégrée de taux d'Arrhenius de capturer l'importance des concentrations et de la température d'espèces sur le procédé d'allumage et de prévoir le début de la combustion. Le cycle pour faire un cycle la dynamique, à leur tour, se développent par l'échange de masse entre un volume de commande représentant le cylindre et une masse de commande modelant la tubulure d'échappement. En dépit de sa simplicité, le modèle prévoit la combustion mettant en phase, pressurise l'évolution et fonctionne le rendement pour des expériences de combustion de propane aux niveaux de la fidélité comparables à des représentations plus complexes. Des réponses passagères aux changements de synchronisation de valve sont également capturées et, avec la modification mineure, le modèle peut, en principe, être prolongé pour manipuler une variété de carburants. En ligne : greg.shaver@gmail.com, gerdes@stanford.edu, roelle@stanford.edu, caton@stanford. [...]

Model-based control of HCCI engines using exhaust recompression / Nikhil Ravi in IEEE Transactions on control systems technology, Vol. 18 N° 6 (Novembre 2010) 

Public ISBD [article]  in IEEE Transactions on control systems technology > Vol. 18 N° 6 (Novembre 2010) . - pp. 1289-1302 Titre : Model-based control of HCCI engines using exhaust recompression Type de document : texte imprimé Auteurs : Nikhil Ravi, Auteur ; Roelle, Matthew, J., Auteur ; Hsien-Hsin Liao, Auteur Année de publication : 2011 Article en page(s) : pp. 1289-1302 Note générale : Energie Aéronospatial Langues : Anglais (eng) Mots-clés : Cycle-by-cycle  control  Cyclic  variability  Homogeneous  charge  compression  ignition  (HCCI)  Physical  modeling  Linear  control Index. décimale : 629.1 Résumé : Homogeneous charge compression ignition (HCCI) is one of the most promising piston-engine concepts for the future, providing significantly improved efficiency and emissions characteristics relative to current technologies. This paper presents a framework for controlling an HCCI engine with exhaust recompression and direct injection of fuel into the cylinder. A physical model is used to describe the HCCI process, with the model states being closely linked to the thermodynamic state of the cylinder constituents. Separability between the effects of the control inputs on the desired outputs provides an opportunity to develop a simple linear control scheme, where the fuel is used to control the work output and the valve timings are used to control the phasing of combustion. The controller is tested on both a single and multi-cylinder HCCI engine, demonstrating the value of a physical model-based control approach that allows an easy porting of the control structure from one engine to another. Experimental results show good tracking of both the work output and combustion phasing over a wide operating region on both engines. In addition, the controller is able to balance out differences between cylinders on the multi-cylinder engine testbed, and reduce the cycle-to-cycle variability of combustion. DEWEY : 629.1 ISSN : 1063-6536 En ligne : http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5356220 [article] Model-based control of HCCI engines using exhaust recompression [texte imprimé] / Nikhil Ravi, Auteur ; Roelle, Matthew, J., Auteur ; Hsien-Hsin Liao, Auteur . - 2011 . - pp. 1289-1302. Energie Aéronospatial Langues : Anglais (eng) in IEEE Transactions on control systems technology > Vol. 18 N° 6 (Novembre 2010) . - pp. 1289-1302 Mots-clés : Cycle-by-cycle  control  Cyclic  variability  Homogeneous  charge  compression  ignition  (HCCI)  Physical  modeling  Linear  control Index. décimale : 629.1 Résumé : Homogeneous charge compression ignition (HCCI) is one of the most promising piston-engine concepts for the future, providing significantly improved efficiency and emissions characteristics relative to current technologies. This paper presents a framework for controlling an HCCI engine with exhaust recompression and direct injection of fuel into the cylinder. A physical model is used to describe the HCCI process, with the model states being closely linked to the thermodynamic state of the cylinder constituents. Separability between the effects of the control inputs on the desired outputs provides an opportunity to develop a simple linear control scheme, where the fuel is used to control the work output and the valve timings are used to control the phasing of combustion. The controller is tested on both a single and multi-cylinder HCCI engine, demonstrating the value of a physical model-based control approach that allows an easy porting of the control structure from one engine to another. Experimental results show good tracking of both the work output and combustion phasing over a wide operating region on both engines. In addition, the controller is able to balance out differences between cylinders on the multi-cylinder engine testbed, and reduce the cycle-to-cycle variability of combustion. DEWEY : 629.1 ISSN : 1063-6536 En ligne : http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5356220

Physics-based modeling and control of residual-affected HCCI engines / Shaver, Gregory. M. in Transactions of the ASME . Journal of dynamic systems, measurement, and control, Vol. 131 N°2 (Mars/Avril 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of dynamic systems, measurement, and control > Vol. 131 N°2 (Mars/Avril 2009) . - 12 p. Titre : Physics-based modeling and control of residual-affected HCCI engines Type de document : texte imprimé Auteurs : Shaver, Gregory. M., Auteur ; Gerdes, Christian J., Auteur ; Roelle, Matthew, J., Auteur Année de publication : 2009 Article en page(s) : 12 p. Note générale : dynamic systems Langues : Anglais (eng) Mots-clés : physics;  pressure;  combustion;  control  equipment;  engines;  valves;  compression;  cycles;  cylinders;  exhaust  systems;  model  validation;  homogeneous  charge  compression  ignition  engines Résumé : Homogeneous charge compression ignition (HCCI) is a novel combustion strategy for IC engines that exhibits dramatic decreases in fuel consumption and exhaust emissions. Originally conceived in 1979, the HCCI methodology has been revisited several times by industry but has yet to be implemented because the process is difficult to control. To help address these control challenges, the authors here outline the first generalizable, validated, and experimentally implemented physics-based control methodology for residual-affected HCCI engines. Specifically, the paper describes the formulation and validation of a two-input, two-state control-oriented system model of the residual-affected HCCI process occurring in a single engine cylinder. The combustion timing and peak pressure are the model states, while the inducted gas composition and effective compression ratio are the model inputs. The resulting model accurately captures the system dynamics and allows the simultaneous, coordinated control of both in-cylinder pressure and combustion timing. To demonstrate this, an H2 optimal controller is synthesized from a linearized version of the model and used to dictate step changes in both combustion timing and peak pressure within about four to five engine cycles on an experimental test bed. The application of control also results in reductions in the standard deviation for both combustion timing and peak pressure. The approach therefore provides accurate mean tracking, as well as a reduction in cyclic dispersion. Another benefit of the simultaneous coordination of both control inputs is a reduction in the control effort required to elicit the desired response. Instead of using a peak pressure controller that must compensate for the effects of a combustion timing controller, and vice versa, the coordinated approach optimizes the use of both control inputs to regulate both outputs. DEWEY : 629.8 ISSN : 0022-0434 En ligne : http://dynamicsystems.asmedigitalcollection.asme.org/issue.aspx?journalid=117&is [...] [article] Physics-based modeling and control of residual-affected HCCI engines [texte imprimé] / Shaver, Gregory. M., Auteur ; Gerdes, Christian J., Auteur ; Roelle, Matthew, J., Auteur . - 2009 . - 12 p. dynamic systems Langues : Anglais (eng) in Transactions of the ASME . Journal of dynamic systems, measurement, and control > Vol. 131 N°2 (Mars/Avril 2009) . - 12 p. Mots-clés : physics;  pressure;  combustion;  control  equipment;  engines;  valves;  compression;  cycles;  cylinders;  exhaust  systems;  model  validation;  homogeneous  charge  compression  ignition  engines Résumé : Homogeneous charge compression ignition (HCCI) is a novel combustion strategy for IC engines that exhibits dramatic decreases in fuel consumption and exhaust emissions. Originally conceived in 1979, the HCCI methodology has been revisited several times by industry but has yet to be implemented because the process is difficult to control. To help address these control challenges, the authors here outline the first generalizable, validated, and experimentally implemented physics-based control methodology for residual-affected HCCI engines. Specifically, the paper describes the formulation and validation of a two-input, two-state control-oriented system model of the residual-affected HCCI process occurring in a single engine cylinder. The combustion timing and peak pressure are the model states, while the inducted gas composition and effective compression ratio are the model inputs. The resulting model accurately captures the system dynamics and allows the simultaneous, coordinated control of both in-cylinder pressure and combustion timing. To demonstrate this, an H2 optimal controller is synthesized from a linearized version of the model and used to dictate step changes in both combustion timing and peak pressure within about four to five engine cycles on an experimental test bed. The application of control also results in reductions in the standard deviation for both combustion timing and peak pressure. The approach therefore provides accurate mean tracking, as well as a reduction in cyclic dispersion. Another benefit of the simultaneous coordination of both control inputs is a reduction in the control effort required to elicit the desired response. Instead of using a peak pressure controller that must compensate for the effects of a combustion timing controller, and vice versa, the coordinated approach optimizes the use of both control inputs to regulate both outputs. DEWEY : 629.8 ISSN : 0022-0434 En ligne : http://dynamicsystems.asmedigitalcollection.asme.org/issue.aspx?journalid=117&is [...]