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Heat Transfer Enhancement

A Numerical Study of the Flow and Heat Transfer in the Pin Fin-Dimple Channels With Various Dimple Depths

[+] Author and Article Information
Yu Rao1

Department Mechanical and Power Engineering,  Institute of Turbomachinery, Shanghai Jiaotong University,Dongchuan Road 800, Shanghai 200240, P.R. Chinayurao@sjtu.edu.cn

Yamin Xu

School of Aeronautics and Astronautics,  Shanghai Jiaotong University, Dongchuan Road 800, Shanghai 200240, P.R. China

Chaoyi Wan

Department Mechanical and Power Engineering,  Institute of Turbomachinery, Shanghai Jiaotong University, Dongchuan Road 800, Shanghai 200240, P.R. China

1

Corresponding author.

J. Heat Transfer 134(7), 071902 (May 24, 2012) (9 pages) doi:10.1115/1.4006098 History: Received June 27, 2011; Revised November 23, 2011; Published May 24, 2012; Online May 24, 2012

A numerical study was conducted to investigate the effects of dimple depth on the flow and heat transfer characteristics in a pin fin-dimple channel, where dimples are located spanwisely between the pin fins. The study aimed at promoting the understanding of the underlying convective heat transfer mechanisms in the pin fin-dimple channels and improving the cooling design for the gas turbine components. The flow structure, friction factor, and heat transfer performance of the pin fin-dimple channels with various dimple depths have been obtained and compared with each other for the Reynolds number range of 8200–80,800. The study showed that, compared to the pin fin channel, the pin fin-dimple channels have further improved convective heat transfer performance, and the pin fin-dimple channel with deeper dimples shows relatively higher Nusselt number values. The study still showed a dimple depth-dependent flow friction performance for the pin fin-dimple channels compared to the pin fin channel, and the pin fin-dimple channel with shallower dimples shows relatively lower friction factors over the studied Reynolds number range. Furthermore, the computations showed the detailed characteristics in the distribution of the velocity and turbulence level in the flow, which revealed the underlying mechanisms for the heat transfer enhancement and flow friction reduction phenomenon in the pin fin-dimple channels.

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Copyright © 2012 by American Society of Mechanical Engineers
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Figures

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Figure 1

Schematic of geometrical configurations of the pin fin-dimple channel with δ/D = 0.2

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Figure 2

Schematic of the boundary conditions in the computation

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Figure 3

The mesh in the flow region in the pin fin-dimple channel with δ/D = 0.2

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Figure 4

Comparisons of the numerical and the experimental averaged Nusselt number and friction factor of the pin fin channel and the pin fin-dimple channel with δ/D = 0.2

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Figure 5

Comparisons of the streamwise velocity profile in the minimum cross-section spanwisely between the pin fins in the pin fin-dimple channels with various dimple depths at Re = 50,500

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Figure 6

Comparisons of the streamline in the minimum cross-section spanwisely between the pin fins in the pin fin-dimple channels with various dimple depths at Re = 50,500

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Figure 7

Comparisons of the turbulent kinetic energy distribution in the minimum cross-section spanwisely between the pin fins in the pin fin-dimple channels with various dimple depths at Re = 50,500

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Figure 8

Comparisons of the streamwise velocity in a plane with a distance of 0.5 mm away from the endwall in the pin fin-dimple channels with various dimple depths at Re = 50,500

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Figure 9

Comparison of streamlines in a plane with a distance of 0.5 mm away from the endwall in the pin fin-dimple channels with various dimple depths at Re = 50,500

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Figure 10

Comparisons of turbulent kinetic energy distribution in a plane with a distance of 0.5 mm away from the endwall in the pin fin-dimple channels with various dimple depths at Re = 50,500

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Figure 11

Comparisons of the turbulent kinetic energy distribution in the longitudinal central plane in the pin fin-dimple channels with various dimple depths at Re = 50,500

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Figure 12

Comparisons of the friction factors of the pin fin-dimple channels with various dimple depths

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Figure 13

Comparisons of globally averaged Nusselt numbers in the pin fin-dimple channels with various dimple depths

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Figure 14

Comparisons of the local Nusselt numbers on the endwall in the pin fin-dimple channels with various dimple depths at Re = 50,500

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Figure 15

Comparisons of the temperature contours on the endwall in the pin fin-dimple channels with various dimple depths at Re = 50,500

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Figure 16

Comparison of the overall thermal performance of the pin fin-dimple channels with various dimple depths

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