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  • ASME International  (3)
Materialart
Verlag/Herausgeber
  • ASME International  (3)
Sprache
Erscheinungszeitraum
  • 1
    Online-Ressource
    Online-Ressource
    ASME International ; 1998
    In:  Journal of Engineering for Gas Turbines and Power Vol. 120, No. 4 ( 1998-10-01), p. 843-854
    In: Journal of Engineering for Gas Turbines and Power, ASME International, Vol. 120, No. 4 ( 1998-10-01), p. 843-854
    Kurzfassung: A ring-dynamics and gas-flow model has been developed to study ring/groove contact, blowby, and the influence of ring static twist, keystone ring/groove configurations, and other piston and ring parameters. The model is developed for a ring pack with three rings. The dynamics of the top two rings and the gas pressures in the regions above the oil control ring are simulated. Distributions of oil film thickness and surface roughness on the groove and ring surfaces are assumed in the model to calculate the forces generated by the ring/groove contact. Ring static and dynamic twists are considered, as well as different keystone ring/groove configurations. Ring dynamics and gas flows are coupled in the formulation and an implicit scheme is implemented, enabling the model to resolve detailed events such as ring flutter. Studies on a spark ignition engine found that static twist or, more generally speaking, the relative angle between rings and their grooves, has great influence on ring/groove contact characteristics, ring stability, and blowby. Ring flutter is found to occur for the second ring with a negative static twist under normal operating conditions and for the top ring with a negative static twist under high-speed/low-load operating conditions. Studies on a diesel engine show that different keystone ring/groove configurations result in different twist behaviors of the ring that may affect the wear pattern of the keystone ring running surfaces.
    Materialart: Online-Ressource
    ISSN: 0742-4795 , 1528-8919
    Sprache: Englisch
    Verlag: ASME International
    Publikationsdatum: 1998
    ZDB Id: 2010437-6
    ZDB Id: 165371-4
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    Online-Ressource
    Online-Ressource
    ASME International ; 1991
    In:  Journal of Engineering for Gas Turbines and Power Vol. 113, No. 3 ( 1991-07-01), p. 319-330
    In: Journal of Engineering for Gas Turbines and Power, ASME International, Vol. 113, No. 3 ( 1991-07-01), p. 319-330
    Kurzfassung: The past twenty years has seen an explosion in our knowledge of engine processes, steadily improving engine power density and efficiency, major reductions in exhaust emissions, and a substantial increase in engine sophistication and complexity. This paper explains how engineering analysis has played a major enabling role in realizing these improvements in spark-ignition engine performance. Examples are given of the many different types of analysis tool in areas such as combustion, emissions, stress analysis, system dynamics, and fluid flow that have been found useful in resolving different engine development and design problems and opportunities. The significant improvements achieved in engine fuel consumption, power density, and emissions control are then reviewed. It is argued, however, that the improvements in urban air quality do not correspond to the reductions achieved in vehicle exhaust emissions. Our current understanding of the link between vehicle emissions and air quality does not explain this discrepancy. What matters is low enough in-use emission, and future regulations do not adequately focus on this essential requirement. An available energy analysis of the four-stroke spark-ignition engine operating cycle is used to identify where opportunities for further increases in efficiency and power are to be found. Approaches that would improve combustion efficiency, reduce heat losses, increase expansion stroke work, reduce pumping work, and decrease friction are discussed. It is concluded that many analysis tools are now available to identify more precisely how large these opportunities are, and how best they might be realized. The potential of various modifications to the four-stroke cycle SI engine cycle, and alternative spark-ignition and diesel cycles, are reviewed. Finally, it is argued that relative to Europe and Japan, the United States lacks a sufficiently broad and organized research effort designed to support the exploration and development of these opportunities.
    Materialart: Online-Ressource
    ISSN: 0742-4795 , 1528-8919
    Sprache: Englisch
    Verlag: ASME International
    Publikationsdatum: 1991
    ZDB Id: 2010437-6
    ZDB Id: 165371-4
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Online-Ressource
    Online-Ressource
    ASME International ; 1989
    In:  Journal of Engineering for Gas Turbines and Power Vol. 111, No. 3 ( 1989-07-01), p. 451-457
    In: Journal of Engineering for Gas Turbines and Power, ASME International, Vol. 111, No. 3 ( 1989-07-01), p. 451-457
    Kurzfassung: The diesel combustion process in direct-injection diesel engines consists of four distinct stages: an ignition delay, a premixed phase, a mixing-controlled phase, and a late combustion phase. This paper uses geometric information from high-speed direct and shadowgraph movies and corresponding combustion chamber pressure histories, taken in a rapid compression machine study of direct-injection diesel combustion, for a coupled analysis of the diesel flame geometry and energy or heat release to develop our understanding of the diesel spray and flame structure during the ignition delay period and premixed combustion phase. It is shown that each fuel spray from a multihole fuel-injector nozzle consists of a narrow liquid-containing core centered within a much larger fuel-vapor air region, which has a distinct boundary. The liquid core does not penetrate to the chamber periphery, while the vapor containing spray interacts strongly with the boundary. Ignition occurs part way along each growing spray. Once combustion starts, the outer boundary of the fuel-vapor-containing region expands more rapidly due to the combustion energy release. Very high initial spreading rates of the luminous region boundary are observed. A comparison of enflamed areas and volumes, and burned gas volumes, indicates that the luminous region during the early stages of combustion (assumed stoichiometric) is around 1 cm thick and does not fill the full height of the chamber. During the premixed combustion phase, the burned gas volume is one-half the enflamed volume, indicating the presence of a substantial unburned (rich) fuel-vapor/air core within the luminous region of each fuel spray. A close correspondence of flame geometry to spray geometry is evident throughout the combustion process.
    Materialart: Online-Ressource
    ISSN: 0742-4795 , 1528-8919
    Sprache: Englisch
    Verlag: ASME International
    Publikationsdatum: 1989
    ZDB Id: 2010437-6
    ZDB Id: 165371-4
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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