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Research Papers: Forced Convection

Heat Transfer in High-Speed Rotating Trapezoidal Duct With Rib-Roughened Surfaces and Air Bleeds From the Wall on the Apical Side

[+] Author and Article Information
Shyy Woei Chang1

Thermal Fluids Laboratory, Department of Marine Engineering, National Kaohsiung Marine University, No. 142, Haijhuan Road, Nanzih District, 811 Kaohsiung, Taiwan, R.O.C.swchang@mail.nkmu.edu.tw

Tong-Minn Liou

Department of Power Mechanical Engineering, National Tsing Hua University, 300 Hsinchu, Taiwan, R.O.C.

Shyr Fuu Chiou

Thermal Fluids Laboratory, National Kaohsiung Marine University, No. 142, Haijhuan Road, Nanzih District, 81143 Kaohsiung, Taiwan, R.O.C.

Shuen Fei Chang

Department of Marine Engineering, National Kaohsiung Marine University, No. 142, Haijhuan Road, Nanzih District, 811 Kaohsiung, Taiwan, R.O.C.

1

Corresponding author.

J. Heat Transfer 130(6), 061702 (Apr 22, 2008) (13 pages) doi:10.1115/1.2891217 History: Received January 07, 2007; Revised August 17, 2007; Published April 22, 2008

An experimental study of heat transfer in a radially rotating trapezoidal duct with two opposite walls roughened by 45deg staggered ribs and bleed from the apical side wall is performed. Centerline heat transfer variations on two rib-roughened surfaces are measured for radially outward flows with and without bleeds at test conditions of Reynolds number (Re), rotation number (Ro), and density ratio (Δρρ) in the ranges of 15,000–30,000, 0–0.8, and 0.04–0.31, respectively. Geometrical configurations and rotation numbers tested have considerably extended the previous experiences that offer practical applications to the trailing edge cooling of a gas turbine rotor blade. A selection of experimental data illustrates the individual and interactive influences of Re, Ro, and buoyancy number (Bu) on local heat transfer with and without bleeds. Local heat transfer results are generated with the influences of bleeds on the apical side examined to establish heat transfer correlations with Re, Ro, and Bu as the controlling flow parameters for design applications. The rotation of present trapezoidal duct with rib-roughened surfaces and air bleeds on the apical side worsens the impairing heat transfer impacts due to bleeds. Within the Ro range of 0.1–0.8, bleeds on the apical side of the rotating channel respectively produce 25–50% and 25–40% of heat transfer reductions from the rotational no-bleed references along the leading and trailing centerlines. Such heat transfer reductions due to the combined bleeds and Ro-Bu impacts need design precautions for turbine rotor blades.

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Copyright © 2008 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Variations of the total coolant extraction (ṁbleed) and fraction (ṁbleed∕ṁ) versus Re in the static channel with bleeds

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Figure 2

Heat transfer test module

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Figure 3

Axial distributions of Tw, Tb, and Nu0∕Nu∞ in the static channels with and without bleeds at a Reynolds number of 25,000

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Figure 4

Axial distributions of Tw, Tb, and Nu∕Nu∞ along leading and trailing edges at Re=25,000 and Ro=0.3 for two rotating channels with and without bleed

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Figure 5

Axial distributions of Nu∕Nu∞ ratios along leading and trailing centerlines with Re=15,000, 20,000, 25,000, and 30,000 at a rotation number of 0.3 for the rotating channels with and without bleed

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Figure 6

Axial distributions of Nubleed∕Nunobleed along (a) leading and (b) trailing edges of the bleed section at Ro=0, 0.1, 0.4, and 0.6 with nominal Re and β(Tw−Tb) of 20,000 and 0.14

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Figure 7

Axial distributions of the Nu∕Nu0 ratio along leading and trailing centerlines of the bleed channel with Re=15,000, 20,000, 25,000, and 30,000 at rotation numbers of 0.1, 0.2, 0.3, 0.4, and 0.5

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Figure 8

Variations of the Nu∕Nu0 ratio against Bu at fixed rotation numbers

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Figure 9

Variations of the zero-buoyancy heat transfer data against Ro at axial locations in the bleed section

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Figure 10

Variations of the ϕ2 value against Ro for rotating channels with and without bleed

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Figure 11

Comparison of experimental measurements and correlative evaluations of Nu∕Nu0.

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