In a state-of-the-art lean-burn spark ignition engine, a strong in-cylinder flow field with enhanced turbulence intensity is formed, and understanding the wall heat transfer mechanism of such a complex flow is required. The flow velocity and temperature profiles inside the wall boundary layer are strongly related to the heat transfer mechanism. In this study, two-dimensional three-component (2D3C) velocity distribution near the piston top surface was measured during the compression stroke in a strong tumble flow using a rapid compression and expansion machine (RCEM) and a stereoscopic micro-PIV system. The bore, stroke, compression ratio, and compression time were 75 mm, 128 mm, 15, and 30 ms (equivalent to 1000 rpm), respectively. A double-pulse Nd:YAG laser sheet was introduced from the intake side, and PIV images were captured near the piston surface around the TDC under motored conditions with a measurement region of 5.2 mm × 6.9 mm (1200 × 1600 pixel, 4.3 μm/pixel) using two CCD cameras. The 2D3C velocity fields show that the magnitude of the wall-tangential velocity (u) is generally larger than the wall-normal velocity (v) and comparable to the tumble axial (laser sheet-normal) velocity (w). As the measured time approaches TDC, u and v tend to decay, while w does not decay compared to u. As a result, the w component contributes more to the 3D vector magnitude than u and v at the closest observation time to TDC. In addition, the main flow is in the piston horizontal direction, and the direction fluctuates in the tumble axial direction because the w direction fluctuates in each cycle. Moreover, separation of the large and small-scale velocity components using a spatial filter enables calculation of turbulent kinetic energy (TKE) at the region near the piston top surface. The contribution of v’, u’, and w’ to TKE increases in this order. Additionally, a large cycle-to-cycle variation of TKE was observed.


    Access

    Check access

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Stereoscopic Micro-PIV Measurement of Near-Wall Velocity Distribution in Strong Tumble Flow under Motored SI Engine Condition


    Additional title:

    Sae Technical Papers


    Contributors:

    Conference:

    SAE Powertrains, Fuels & Lubricants Meeting ; 2020



    Publication date :

    2020-09-15




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




    Stereoscopic Micro-PIV Measurement of Near-Wall Velocity Distribution in Strong Tumble Flow under Motored SI Engine Condition

    Yamakita, Yoko / Bae, Jaeok / Nagasawa, Tsuyoshi et al. | British Library Conference Proceedings | 2020


    Frequency Analysis of Tumble and Swirl in Motored Engines

    Arcoumanis, C / Enotiadis, A C / Whitelaw, J H | SAGE Publications | 1991


    Frequency analysis of tumble and swirl in motored engines

    Arcoumanis,C. / Enotiadis,A.C. / Whitelaw,J.H. et al. | Automotive engineering | 1991


    PIV Measurements of In-Cylinder Tumble Flow in a Motored Single Cylinder Optical Research Engine

    Gomes, Carlos Alberto / Franco, Rafael Lara / Valle, Ramon Molina et al. | SAE Technical Papers | 2015


    Near-Wall Velocity Characteristics in Valved and Ported Motored Engines

    Ghandhi, Jamshed B. / Martin, Jay K. / Pierce, Philip H. | SAE Technical Papers | 1992