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RESEARCH PAPERS

# Design and Thermal Characteristics of a Synthetic Jet Ejector Heat Sink

[+] Author and Article Information
Raghav Mahalingam1

Fluid Mechanics and Heat Transfer Research Labs, George W. Woodruff School of Mechanical Engineering,  Georgia Institute of Technology, Atlanta, GA 30332raghav.mahalingam@me.gatech.edu

Ari Glezer

Fluid Mechanics and Heat Transfer Research Labs, George W. Woodruff School of Mechanical Engineering,  Georgia Institute of Technology, Atlanta, GA 30332ari.glezer@me.gatech.edu

1

Phone: (404) 385-1892, Fax: (404) 894-8496

J. Electron. Packag 127(2), 172-177 (Dec 23, 2004) (6 pages) doi:10.1115/1.1869509 History: Received January 27, 2003; Revised December 23, 2004

## Abstract

The design and thermal performance of a synthetic-air-jet-based heat sink for high-power dissipation electronics is discussed. Each fin of a plate-fin heat sink is straddled by a pair of two-dimensional synthetic jets, thereby creating a jet ejector system that entrains cool ambient air upstream of the heat sink and discharges it into the channels between the fins. The jets are created by periodic pressure variations induced in a plenum by electromagnetic actuators. The performance of the heat sink is assessed using a thermal test die encased in a heat spreader that is instrumented with a thermocouple. The case-to-ambient thermal resistance under natural convection with the heat sink is $3.15°C∕W$. Forced convection with the synthetic jets enables a power dissipation of $59.2W$ at a case temperature of $70°C$, resulting in a case-to-ambient thermal resistance of $0.76°C∕W$. The synthetic-jet heat sink dissipates $∼40%$ more heat compared to steady flow from a ducted fan blowing air through the heat sink. The synthetic jets generate a flow rate of 4.48 CFM through the heat sink, resulting in 27.8 W/CFM and thermal effectiveness of 0.62. The effect of fin length on the thermal resistance of the heat sink is discussed. Detailed measurements on an instrumented heat sink estimate that the average heat transfer coefficients in the channel flow between the fins is 2.5 times that of a steady flow in the ducts at the same Reynolds Number.

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Copyright © 2005 by American Society of Mechanical Engineers
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## Figures

Figure 6

Variation of exit velocity along the height of the channel

Figure 7

Air temperature along the center channel of the heat sink

Figure 8

Effect of fin length on the thermal resistance of the heat sink

Figure 9

Variation of exit air temperature with die temperature

Figure 10

Effect of actuator frequency on thermal resistance of the heat sink

Figure 11

Volume flow rate within the different channels in the heat sink

Figure 1

Basic principle of operation of a synthetic jet ejector

Figure 2

Schematic diagram of the synthetic jet heat sink. A single channel is shown for clarity in the bottom figure. The module consists of 17 identical channels, with addition shorter fins within each channel to increase the surface area.

Figure 3

Rapid cooling capability of synthetic jet ejector heat sink

Figure 4

Comparison of synthetic jet and natural convection (엯) natural convection, (●) synthetic jet)

Figure 5

Comparison of the thermal performance of synthetic jets (◆) and steady fan driven flow (●)

Figure 12

Variation in fin (엯) and exit air temperatures (●) across the channels of the heat sink.

Figure 13

Comparison of the heat transfer coefficient between synthetic jet ejector channel flow (◆) and empirical correlation for a fully developed steady duct flow (—)

## Errata

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