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TECHNICAL PAPERS

# Jet Impingement Cooling of Chips Equipped With Multiple Cylindrical Pedestal Fins

[+] Author and Article Information
D. H. Lee

School of Mechanical and Automotive Engineering, Inje University, 607 Obang-dong, Gimhae, Gyongnam 621-749 Korea

Y. S. Chung

Samsung Electronics Co., Ltd., 416, Maetan3-dong, Paldal-gu, Suwon, Gyeonggi-do 442-742, Korea

P. M. Ligrani

Donald Schultz Professor of Turbomachinery, Director, Thermo-Fluids Laboratory, Department of Engineering Science, Oxford University, Parks Road, Oxford OX1 3PJ, United Kingdom

J. Electron. Packag 129(3), 221-228 (Oct 30, 2006) (8 pages) doi:10.1115/1.2753884 History: Received November 28, 2004; Revised October 30, 2006

## Abstract

Fluid flow and heat transfer characteristics on and around a central pedestal and a secondary pedestal, mounted on a flat surface with an impinging jet, are investigated. Surface Nusselt numbers, pressure coefficients (in the form of normalized wall static pressure relative to freestream static pressure), and flow visualization results are given for jet Reynolds numbers of 23,000 and 2300. The dimensionless nozzle-to-surface distance $L∕d$ is 2, and the nondimensional height of the central pedestal $H∕D$ is 0.5. Results are given for different secondary pedestal heights and locations. Spatially averaged Nusselt numbers measured with secondary pedestals employed are 13% to 33% higher than values measured with no secondary pedestal. Local Nusselt numbers and wall pressure coefficients, measured with the secondary pedestal present, are different from values measured with no secondary pedestal, because of flow reattachment and the two counter-rotating recirculation zones located between the two pedestals, and small local regions of flow separation and recirculation located on top of the secondary pedestal. As such, the present multiple pedestal data with impinging jets are useful for a variety of electronics cooling arrangements.

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## Figures

Figure 1

Schematic diagram of the impinging jet and multiple cylindrical pedestals arrangement

Figure 2

Schematic diagram of the experimental apparatus

Figure 3

Schematic diagram of the experimental apparatus employed for pressure coefficient measurements

Figure 4

Visualization of flow patterns along the surface with pedestals for H∕D=0.5, H2∕D=0.4, p∕D=2.0, and L∕d=2

Figure 5

Visualization of flow patterns along the surface with pedestals for H∕D=0.5, H2∕D=0.4, p∕D=2.5, and L∕d=2

Figure 6

Visualization of flow patterns along the surface with pedestals for H∕D=0.5, H2∕D=0.4, p∕D=3.0, and L∕d=2

Figure 7

Variation of wall pressure coefficients along the pedestal and flat surface for Re=23,000, p∕D=2.0, H∕D=0.5, and L∕d=2

Figure 8

Variation of wall pressure coefficients along the pedestal and flat surface for Re=23,000, p∕D=2.5, H∕D=0.5, and L∕d=2

Figure 9

Variation of wall pressure coefficients along the pedestal and flat surface for Re=23,000, p∕D=3.0, H∕D=0.5, and L∕d=2

Figure 10

Streamwise distribution of local Nusselt numbers along the surface with pedestals for Re=23,000, p∕D=2.0, H∕D=0.5, and L∕d=2

Figure 11

Streamwise distribution of local Nusselt numbers along the surface with pedestals for Re=23,000, p∕D=2.5, H∕D=0.5, and L∕d=2

Figure 12

Streamwise distribution of local Nusselt numbers along the surface with pedestals for Re=23,000, p∕D=3.0, H∕D=0.5, and L∕d=2

Figure 13

Spatially averaged Nusselt numbers as they vary with r∕d at different H2∕D for p∕D=2.0

Figure 14

Spatially averaged Nusselt numbers as they vary with r∕d at different H2∕D for p∕D=2.5

Figure 15

Spatially averaged Nusselt numbers as they vary with r∕d at different H2∕D for p∕D=3.0

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