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    Effects of Density and Blowing Ratios on the Turbulent Structure and Effectiveness of Film Cooling

    Source: Journal of Turbomachinery:;2018:;volume 140:;issue 010::page 101007
    Author:
    Stratton, Zachary T.
    ,
    Shih, Tom I-P.
    DOI: 10.1115/1.4041218
    Publisher: The American Society of Mechanical Engineers (ASME)
    Abstract: Large eddy simulations (LES) were performed to investigate film cooling of a flat plate, where the cooling jets issued from a plenum through one row of circular holes of diameter D and length 4.7D that are inclined at 35 deg relative to the plate. The focus is on understanding the turbulent structure of the film-cooling jet and the film-cooling effectiveness. Parameters studied include blowing ratio (BR = 0.5 and 1.0) and density ratio (DR = 1.1 and 1.6). Also, two different boundary layers (BL) upstream of the film-cooling hole were investigated—one in which a laminar BL was tripped to become turbulent from near the leading edge of the flat plate, and another in which a mean turbulent BL is prescribed directly. The wall-resolved LES solutions generated were validated by comparing its time-averaged values with data from PIV and thermal measurements. Results obtained show that having an upstream BL that does not have turbulent fluctuations enhances the cooling effectiveness significantly at low velocity ratios (VR) when compared to an upstream BL that resolved the turbulent fluctuations. However, these differences diminish at higher VRs. Instantaneous flow reveals a bifurcation in the jet vorticity as it exits the hole at low VRs, one branch forming the shear-layer vortex, while the other forms the counter-rotating vortex pair (CRVP). At higher VRs, the shear layer vorticity is found to reverse direction, changing the nature of the turbulence and the heat transfer. Results obtained also show the strength and structure of the turbulence in the film-cooling jet to be strongly correlated to VR.
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      Effects of Density and Blowing Ratios on the Turbulent Structure and Effectiveness of Film Cooling

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    contributor authorStratton, Zachary T.
    contributor authorShih, Tom I-P.
    date accessioned2019-02-28T11:09:57Z
    date available2019-02-28T11:09:57Z
    date copyright9/28/2018 12:00:00 AM
    date issued2018
    identifier issn0889-504X
    identifier otherturbo_140_10_101007.pdf
    identifier urihttp://yetl.yabesh.ir/yetl1/handle/yetl/4253367
    description abstractLarge eddy simulations (LES) were performed to investigate film cooling of a flat plate, where the cooling jets issued from a plenum through one row of circular holes of diameter D and length 4.7D that are inclined at 35 deg relative to the plate. The focus is on understanding the turbulent structure of the film-cooling jet and the film-cooling effectiveness. Parameters studied include blowing ratio (BR = 0.5 and 1.0) and density ratio (DR = 1.1 and 1.6). Also, two different boundary layers (BL) upstream of the film-cooling hole were investigated—one in which a laminar BL was tripped to become turbulent from near the leading edge of the flat plate, and another in which a mean turbulent BL is prescribed directly. The wall-resolved LES solutions generated were validated by comparing its time-averaged values with data from PIV and thermal measurements. Results obtained show that having an upstream BL that does not have turbulent fluctuations enhances the cooling effectiveness significantly at low velocity ratios (VR) when compared to an upstream BL that resolved the turbulent fluctuations. However, these differences diminish at higher VRs. Instantaneous flow reveals a bifurcation in the jet vorticity as it exits the hole at low VRs, one branch forming the shear-layer vortex, while the other forms the counter-rotating vortex pair (CRVP). At higher VRs, the shear layer vorticity is found to reverse direction, changing the nature of the turbulence and the heat transfer. Results obtained also show the strength and structure of the turbulence in the film-cooling jet to be strongly correlated to VR.
    publisherThe American Society of Mechanical Engineers (ASME)
    titleEffects of Density and Blowing Ratios on the Turbulent Structure and Effectiveness of Film Cooling
    typeJournal Paper
    journal volume140
    journal issue10
    journal titleJournal of Turbomachinery
    identifier doi10.1115/1.4041218
    journal fristpage101007
    journal lastpage101007-12
    treeJournal of Turbomachinery:;2018:;volume 140:;issue 010
    contenttypeFulltext
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    DSpace software copyright © 2002-2015  DuraSpace
    نرم افزار کتابخانه دیجیتال "دی اسپیس" فارسی شده توسط یابش برای کتابخانه های ایرانی | تماس با یابش
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