In computational fluid dynamic simulations of partially premixed combustion engines it is common to find simplifications of the in cylinder flow conditions in order to save computational cost. One common simplification is to start the simulation at the moment of intake valve closing with an assumed initial flow condition, rather than making a full scavenging simulation. Another common simplification is the periodic sector assumption, limiting all sector cuts of the full cylinder to be identical periodic copies of each other. This work studies how such flow simplifications affect the spray injection and in turn the fuel/air mixing at different injection timings. Focus is put on the stratification of fuel concentration and gas temperature due to interaction of the spray, turbulence and piston geometry. The investigated engine setup consists of a light duty engine with a piston bowl and a five-hole injector. The simulations are performed under non-reacting conditions and utilize the large eddy simulation turbulence model. Both full cylinder mesh and sector mesh simulations are carried out to evaluate the effects of (a) turbulent vs non-turbulent initial conditions at intake valve closing, (b) sector periodicity assumption on the fuel/air mixing in the compression stroke under different PPC injection timings. The unresolved scales are modeled using a transported one-equation sub-grid scale (SGS) turbulence closure and the fuel spray is modelled using Lagrangian particle tracking (LPT). The simulations show that simple laminar initial conditions produce similar levels of mixing as advanced initial conditions with tilted swirl and anisotropic turbulence. The influence of sector periodicity restriction compared to a full cylinder simulation shows slightly increased levels of stratification in terms of temperature and fuel concentration. This difference is shown to depend on turbulent scales at the center of the cylinder inside the piston bowl and was strongest for the advanced injection timings but could also be observed for the earliest injections.


    Zugriff

    Zugriff prüfen

    Verfügbarkeit in meiner Bibliothek prüfen

    Bestellung bei Subito €


    Exportieren, teilen und zitieren



    Titel :

    Effects of In-Cylinder Flow Simplifications on Turbulent Mixing at Varying Injection Timings in a Piston Bowl PPC Engine


    Weitere Titelangaben:

    Sae Technical Papers


    Beteiligte:
    Ibron, Christian (Autor:in) / Jangi, Mehdi (Autor:in) / Bai, Xue-Song (Autor:in)

    Kongress:

    WCX SAE World Congress Experience ; 2019



    Erscheinungsdatum :

    2019-04-02




    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch




    Piston Bowl Optimization for Single Cylinder Diesel Engine Using CFD

    Rathinam, Balamurugan / Lalvani, J Isaac JoshuaRamesh / Annamalai, Kandaswamy et al. | SAE Technical Papers | 2016


    Bowl Geometry Effects on Turbulent Flow Structure in a Direct Injection Diesel Engine

    Warey, Alok / Kurtz, Eric / Perini, Federico et al. | SAE Technical Papers | 2018


    Numerical Estimation of Asymmetry of In-Cylinder Flow in a Light Duty Direct Injection Engine with Re-Entrant Piston Bowl

    Ibron, Christian / Jangi, Mehdi / Lucchini, Tommaso et al. | SAE Technical Papers | 2017


    Piston Bowl Optimization for RCCI Combustion in a Light-Duty Multi-Cylinder Engine

    Hanson, R. / Curran, S. / Wagner, R. et al. | British Library Conference Proceedings | 2012


    DISI engine spark and fuel injection timings - effects, compromise and robustness

    Shayler,P.J. / Jones,S.T. / Horn,G. et al. | Kraftfahrwesen | 2001