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Research Papers

Effect of Uneven Wall Heating Conditions Under Different Buoyancy Numbers for a One Side Rib-Roughened Rotating Channel

[+] Author and Article Information
Zhi Wang

School of Aeronautics and Space,
Universidad Politecnica de Madrid,
Madrid 28040, Spain
e-mail: zhi.wang@upm.es

Roque Corral

Advanced Engineering Direction,
Industria de TurboPropulsores S.A.,
Alcobendas 28108, Spain
e-mail: roque.corral@itp.es

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received August 3, 2017; final manuscript received August 16, 2017; published online September 19, 2017. Editor: Kenneth Hall.

J. Turbomach 139(11), 111011 (Sep 19, 2017) (10 pages) Paper No: TURBO-17-1102; doi: 10.1115/1.4037758 History: Received August 03, 2017; Revised August 16, 2017

This paper investigates the impacts of uneven wall heating conditions under different buoyancy numbers on flow field and heat transfer performance of a rotating channel with one side smooth and one side roughened by 45 deg inclined ribs. Parametric Reynolds-averaged Navier–Stokes (RANS) simulations were conducted under two different wall heating conditions: only ribbed wall heated, as in experiment setup, and all walls heated, under three different buoyancy numbers. Results are compared, when available, with experimental results. Numerical results show that uneven wall heating has only a minor impact on nonrotating cases and very low buoyancy rotating cases. However, it has a significant influence, on both, the heat transfer behavior and the flow field, when the buoyancy number is large. In the ribbed trailing rotating tests, the all walls heated cases show significantly higher heat transfer rate than only the ribbed wall heated cases. The discrepancy is enlarged as buoyancy number increases. The heat transfer in the all walls heated case increases monotonically with the buoyancy number, whereas in the ribbed wall, heated case is slight reduced. In the ribbed leading rotating tests, the heat transfer sensitivity to the heating conditions is not conspicuous, and for both cases, the heat transfer level slightly reduced as the buoyancy number increased. The flow field investigation shows that there is a significant displacement of main flow in the all walls heated cases than only the ribbed wall heated cases under high buoyancy numbers. This displacement is due to the buoyancy effect and responsible for the heat transfer differences in uneven heating problems. According to the results obtained in the paper, we conclude that when buoyancy effects are relevant, the heating settings can play a significant role in the heat transfer mechanisms and therefore in the experimental and numerical results.

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Figures

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Fig. 1

Cooling channel sketch

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Fig. 2

Hybrid mesh of computational domain

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Fig. 3

Numerical model and boundary conditions

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Fig. 4

Segment index notation

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Fig. 5

Comparison of segment-averaged Nu/Nu0 of the first passage at nominal condition (Re = 15,000, Ro = 0.3 and Bo = 0.17) with the ribbed wall heated

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Fig. 6

Numerical results of Nu/Nu0 distribution for two different wall heating conditions at nominal condition (Re = 15,000, Ro = 0.3, and Bo = 0.17)

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Fig. 7

Evolution of overall Nu/Nu0 for uneven heating conditions as a function of the buoyancy and rotation numbers

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Fig. 8

Effect of uneven heating under rotation as a function of the buoyancy number, solid symbols: all walls heated; hollow symbols: rib wall heated

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Fig. 9

Velocity magnitude and secondary flow patterns at channel inlet

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Fig. 10

Velocity magnitude and secondary flow patterns (arrows) at the middle of segment no. − 3 for uneven wall heating conditions under different buoyancy numbers

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Fig. 11

Streamwise velocity contours and streamlines in inter-rib region for different wall heating conditions under different buoyancy numbers

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Fig. 12

Spanwise velocity contours in inter-rib region for different wall heating conditions under different buoyancy numbers

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Fig. 13

Schematic model of flow in ribbed trailing wall tests, under Coriolis and buoyancy forces

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Fig. 14

Streamwise velocity profile along channel height at middle plane of segment −3 for different wall heating conditions under different buoyancy numbers

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