Direct water injection (DWI) was newly introduced as a promising NOx reduction method for marine diesel engines thanks for its easy installation requiring no major engine modification. Its true potential, however, remains uncertain for lack of both numerical and experimental investigations. In this study, the effect of DWI on decreasing flame temperature was objectively examined by two simulation codes of different combustion models and by flame temperature measurement in a visual engine based on the two-colour method using CMOS type camera. Simulation results were in good agreement with the measurement results in both flame propagation and flame temperature so that NOx reduction of DWI could be clearly explained. Moreover, it was found that DWI could result in more complicated combustion process than expected since preceding water vapour greatly affected the propagation and the air entrainment of the fuel spray. Characteristics of the DWI system with double-needle injector were investigated through visualization tests and also through detailed simulations. The following conclusions were derived: 1. In quiescent air of CVCC, piloting water injection greatly reduced the drag force on the fuel spray from the ambient gas, so that the spray sharpened its front and lengthened its penetration. 2. Simultaneous DWI looked most effective to reduce NOx emission by showing drastic temperature drop in the early combustion stage, whereas flame temperature around the spray root slightly rose up again in the after-burning period. 3. CMOS camera proved to be useful not only for the flame visualization but also for the temperature measurement by the two-colour method. 8-bit colour resolution strictly limited its dynamic range. 4. NO reduction effect by DWI system was clearly demonstrated by the numerical predictions with two different CFD codes. 5. Tendency of NOx reduction with the different DWI configurations was correctly reproduced numerically. The IMEP prediction showed the trade-off relation between engine output and NOx emission. 6. For case C, the injected water penetrated well ahead of the burning fuel spray, away from the NO formation regions. NO reduction in this case is mainly due to reduction in unburned gas temperature due to water evaporation. For case D, the injected water vapour is located in NO-forming regions, especially early in the combustion.


    Zugriff

    Zugriff über TIB

    Verfügbarkeit in meiner Bibliothek prüfen

    Bestellung bei Subito €


    Exportieren, teilen und zitieren



    Titel :

    Diagnosis of combustion with water injection using high-speed visualization and CFDs


    Weitere Titelangaben:

    Verbrennungsdiagnostik mit Wassereinspritzung unter Verwendung der Hochgeschwindigkeitsvisualisierung und von numerischen Strömungssimulationen


    Beteiligte:
    Tajima, H. (Autor:in) / Takasaki, Koji (Autor:in) / Goldsworthy, L. (Autor:in) / Takaishi, T. (Autor:in) / Strom, A. (Autor:in) / Masuda, R. (Autor:in)


    Erscheinungsdatum :

    2004


    Format / Umfang :

    12 Seiten, 11 Bilder, 4 Tabellen, 6 Quellen



    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch




    Combustion with water injection - high-speed visualization and CFDs

    Tajima,H. / Yasueda,S. / Hirayama,Y. et al. | Kraftfahrwesen | 2005


    The Use of CFDS - Flow3D for Vehicle Aerodynamics

    Simcox, S. / Jones, I. P. / Gu, C. Y. et al. | British Library Conference Proceedings | 1994


    High-speed Visualization of Diesel Combustion

    Nakajima, H. / Shiozaki, T. | British Library Online Contents | 1998


    High-Speed Inspection and Visualization of Fuel Injection in the Large Combustion Chamber

    Kotek, L. / Jonák, M. / Drápal, L. et al. | British Library Conference Proceedings | 2014