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Unthrottled Engine Operation using Variable Valve Actuation: The Impact on the Flow Field, Mixing and Combustion
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 16, 2007 by SAE International in United States
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The effect on the intake flow field, air fuel mixing processes, thermodynamic performance and emissions output has been investigated for a range of valve operating profiles. A standard speed load point of 2000 rpm and 2.7 bar IMEP720° has been reached by throttling the intake whilst running standard cam profiles, by early closing of both inlet valves (EIVC) and by early closing of each inlet individually to generate bulk swirl motions within the cylinder. Data has been recorded at stoichiometric air fuel ratios for both direct injection and port fuelled operation.
The valve profiles have been applied to two single cylinder homogeneous gasoline direct injection (GDI) spark ignition engines, developed to investigate the potential of controlling engine load by limiting the inducted air mass using fully variable valve timing (FVVT) to reduce pumping losses at part load. The first engine featured a full length optical liner, allowing 2D Particle Image Velocimetry (PIV) measurements of the intake flow fields to be made, along with Mie imaging studies of the liquid fuel fraction. The second was a thermodynamic engine equipped to measure specific fuel consumption and emissions of CO2, CO, NOX and THC.
The work shows that fuel economy benefits can be gained by operating the engine with unthrottled EIVC operation. However, the interaction between the intake air and direct injection fuel spray means performance is highly dependant upon which valve is operated and the timing of the direct injection fuel spray.
- Graham Pitcher - Powertrain Research, Lotus Engineering Ltd.
- Jamie W. G. Turner - Powertrain Research, Lotus Engineering Ltd.
- Hans Nuglisch - Siemens VDO Automotive S.A.S.
- Jerome Helie - Siemens VDO Automotive S.A.S.
- Philip A. Stansfield - Faculty of Engineering, Loughborough University
- Graham Wigley - Faculty of Engineering, Loughborough University
- Colin P. Garner - Faculty of Engineering, Loughborough University
- Rishin Patel - University College London
- Nicos Ladommatos - University College London
CitationStansfield, P., Wigley, G., Garner, C., Patel, R. et al., "Unthrottled Engine Operation using Variable Valve Actuation: The Impact on the Flow Field, Mixing and Combustion," SAE Technical Paper 2007-01-1414, 2007, https://doi.org/10.4271/2007-01-1414.
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