Auto-ignition with SI-compression ratio can be achieved by replacing some of the fresh charge by hot residuals. In this work an engine is run with a negative valve overlap (NVO) trapping hot residuals. By increasing the NVO, thus raising the initial charge temperature it is possible to investigate the intermediate zone between SI and HCCI as the amount of residuals is increased. Recent research has shown the potential of using spark assistance to aid gasoline HCCI combustion at some operating conditions, and even extend the operating regime into regions where unsupported HCCI combustion is impossible.In this work the influence of the spark is studied in a single cylinder operated engine with optical access. Combustion is monitored by in-cylinder pressure and simultaneous high speed chemiluminescence imaging. It is seen that even for large NVO and thus high residual fractions it is a growing SI flame that interacts with, and governs the subsequent HCCI combustion. Using the spark timing it is possible to phase the combustion timing even when the major part of the released heat is from HCCI combustion. The flame expansion speed is decreases for higher NVO, but prevails also for high residual fractions. A higher spark advance is found to compensate for the slower flame expansion up to a point.The auto-ignition process is found to be stratified for both spark assisted HCCI as well as for pure HCCI. For pure HCCI the initial front spreading velocity is found to be in the same order of magnitude as for the expansion speed of the SI flame.Calculations to estimate the crank angle of auto-ignition are performed based on cylinder pressure information providing good statistics on how the proportion of SI to HCCI behaves for different operating conditions.


    Zugriff

    Zugriff prüfen

    Verfügbarkeit in meiner Bibliothek prüfen

    Bestellung bei Subito €


    Exportieren, teilen und zitieren



    Titel :

    Investigation of the Early Flame Development in Spark Assisted HCCI Combustion Using High Speed Chemiluminescence Imaging


    Weitere Titelangaben:

    Sae Technical Papers


    Beteiligte:
    Hultqvist, A. (Autor:in) / Remón, A. (Autor:in) / Johansson, B. (Autor:in) / Persson, H. (Autor:in)

    Kongress:

    SAE World Congress & Exhibition ; 2007



    Erscheinungsdatum :

    2007-04-16




    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch





    Investigation of the Early Flame Development in Spark Assisted HCCI Combustion Using High Speed Chemiluminescence Imaging

    Persson, H. / Hultqvist, A. / Johansson, B. et al. | British Library Conference Proceedings | 2007


    Investigation of Boundary Layer Behaviour in HCCI Combustion using Chemiluminescence Imaging

    Hultqvist, A. / Johansson, B. / Persson, H. et al. | SAE Technical Papers | 2005


    Spark Assisted HCCI Combustion Using a Stratified Hydrogen Charge

    Berntsson, Andreas / Denbratt, Ingemar | SAE Technical Papers | 2005