Effect of streamwise spacing on periodic and random unsteadiness in a bundle of short cylinders confined in a channel

Jason K. Ostanek, Karen Ann Thole

    Research output: Contribution to journalArticle

    6 Citations (Scopus)

    Abstract

    While flow across long tube bundles is considered classical data, pin-fin arrays made up of short tubes have become a growing topic of interest for use in cooling gas turbine airfoils. Data from the literature indicate that decreasing streamwise spacing increases heat transfer in pin-fin arrays; however, the specific mechanism that causes increased heat transfer coefficients remains unknown. The present work makes use of time-resolved PIV to quantify the effects of streamwise spacing on the turbulent near wake throughout various pin-fin array spacings. Specifically, proper orthogonal decomposition was used to separate the (quasi-) periodic motion from vortex shedding and the random motion from turbulent eddies. Reynolds number flow conditions of 3.0 × 10 3 and 2.0 × 104, based on pin-fin diameter and velocity at the minimum flow area, were considered. Streamwise spacing was varied from 3.46 pin diameters to 1.73 pin diameters while the pin-fin height-to-diameter ratio was unity and the spanwise spacing was held constant at two diameters. Results indicated that (quasi-) periodic motions were attenuated at closer streamwise spacings while the level of random motions was not strongly dependent on pin-fin spacing. This trend was observed at both Reynolds number conditions considered. Because closer spacings exhibit higher heat transfer levels, the present results imply that periodic motions may not contribute to heat transfer, although further experimentation is required.

    Original languageEnglish (US)
    Pages (from-to)1779-1796
    Number of pages18
    JournalExperiments in Fluids
    Volume53
    Issue number6
    DOIs
    StatePublished - Dec 1 2012

    Fingerprint

    bundles
    fins
    spacing
    Heat transfer
    Reynolds number
    Fins (heat exchange)
    Vortex shedding
    Airfoils
    Heat transfer coefficients
    Gas turbines
    heat transfer
    Cooling
    Decomposition
    turbulent wakes
    tubes
    near wakes
    vortex shedding
    airfoils
    gas turbines
    experimentation

    All Science Journal Classification (ASJC) codes

    • Computational Mechanics
    • Mechanics of Materials
    • Physics and Astronomy(all)
    • Fluid Flow and Transfer Processes

    Cite this

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    title = "Effect of streamwise spacing on periodic and random unsteadiness in a bundle of short cylinders confined in a channel",
    abstract = "While flow across long tube bundles is considered classical data, pin-fin arrays made up of short tubes have become a growing topic of interest for use in cooling gas turbine airfoils. Data from the literature indicate that decreasing streamwise spacing increases heat transfer in pin-fin arrays; however, the specific mechanism that causes increased heat transfer coefficients remains unknown. The present work makes use of time-resolved PIV to quantify the effects of streamwise spacing on the turbulent near wake throughout various pin-fin array spacings. Specifically, proper orthogonal decomposition was used to separate the (quasi-) periodic motion from vortex shedding and the random motion from turbulent eddies. Reynolds number flow conditions of 3.0 × 10 3 and 2.0 × 104, based on pin-fin diameter and velocity at the minimum flow area, were considered. Streamwise spacing was varied from 3.46 pin diameters to 1.73 pin diameters while the pin-fin height-to-diameter ratio was unity and the spanwise spacing was held constant at two diameters. Results indicated that (quasi-) periodic motions were attenuated at closer streamwise spacings while the level of random motions was not strongly dependent on pin-fin spacing. This trend was observed at both Reynolds number conditions considered. Because closer spacings exhibit higher heat transfer levels, the present results imply that periodic motions may not contribute to heat transfer, although further experimentation is required.",
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    Effect of streamwise spacing on periodic and random unsteadiness in a bundle of short cylinders confined in a channel. / Ostanek, Jason K.; Thole, Karen Ann.

    In: Experiments in Fluids, Vol. 53, No. 6, 01.12.2012, p. 1779-1796.

    Research output: Contribution to journalArticle

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