The large-scale rotating flow structure in an engine cylinder exhibits features that can be described in generic terms of tumble and swirl. The structural details, nevertheless, vary from cycle to cycle due to fluctuating initial and boundary conditions of the flow. Typical analysis of the flow field cyclic variability - by simple root-mean-square, or additional spatial or temporal filtering, or proper orthogonal decomposition - is based on pointwise deviation of the instantaneous velocity from the ensemble mean. However, that analysis approach is not amenable to the evaluation of spatial variation of the flow structure, in position and orientation, within the flow field. To this end, other studies in the past focused instead on quantifying the variation of the vortex center for the dominant tumble or swirl pattern within the flow field. Yet there is no attempt in the literature to analyze both translational and rotational variations of more complex in-cylinder flow patterns, such as a counter-rotating tumble vortex pair generated during intake. In this paper, the technique of complex moment normalization from pattern recognition applications is extended to enable such an analysis. The algebraic properties of complex moments are introduced and related to the geometric and physical properties of two-dimensional flow fields. Complex moment normalization is then used to analyze a set of in-cylinder flow fields obtained by high-speed particle image velocimetry in the middle tumble plane of an optical engine. The cycle-to-cycle variation of the large-scale tumble flow structure - in magnitude, position, and orientation - are quantified and discussed.


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    Titel :

    Cycle-to-Cycle Variation of In-Cylinder Tumble Flow by Moment Normalization


    Weitere Titelangaben:

    Sae Technical Papers


    Beteiligte:
    Hung, David (Autor:in) / Teh, Kwee-Yan (Autor:in) / Ge, Penghui (Autor:in) / Wang, Yusheng (Autor:in)

    Kongress:

    International Powertrains, Fuels & Lubricants Meeting ; 2017



    Erscheinungsdatum :

    2017-10-08




    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch


    Schlagwörter :


    Cycle-to-Cycle Variation of In-Cylinder Tumble Flow by Moment Normalization

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    Matsuda, Masayoshi / Yokomori, Takeshi / Iida, Norimasa | British Library Conference Proceedings | 2017


    Investigation of Cycle-to-Cycle Variation of Turbulent Flow in a High-Tumble SI Engine

    Matsuda, Masayoshi / Iida, Norimasa / Yokomori, Takeshi | SAE Technical Papers | 2017



    Turbulence and Cycle-by-Cycle Variation of Mean Velocity Generated by Swirl and Tumble Flow and Their Effects on Combustion

    Lee, Ki-Hyung / Murayama, Taichi / Urushihara, Tomonori et al. | SAE Technical Papers | 1995