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RESEARCH PAPERS

# Meso Scale Pulsating Jets for Electronics Cooling

[+] Author and Article Information
Jivtesh Garg, Mehmet Arik, Todd Wetzel

GE Global Research Center, Thermal Systems Laboratory, Niskayuna, NY 12309

Stanton Weaver

GE Global Research Center, Micro and Nano Structures Technology Lab, Niskayuna, NY 12309

GE Global Research Center, Propulsion Technologies Laboratory, Niskayuna, NY 12309

J. Electron. Packag 127(4), 503-511 (Apr 20, 2005) (9 pages) doi:10.1115/1.2065727 History: Received October 11, 2004; Revised April 20, 2005

## Abstract

Microfluid devices are conventionally used for boundary layer control in many aerospace applications. Synthetic jets are intense small-scale turbulent jets formed from periodic entrainment and expulsion of the fluid in which they are embedded. The jets can be made to impinge upon electronic components thereby providing forced convection impingement cooling. The small size of these devices accompanied by the high exit air velocity provides an exciting opportunity to significantly reduce the size of thermal management hardware in electronics. A proprietary meso scale synthetic jet designed at GE Global Research is able to provide a maximum air velocity of $90m∕s$ from a 0.85 mm hydraulic diameter rectangular orifice. An experimental study for determining the cooling performance of synthetic jets was carried out by using a single jet to cool a thin foil heater. The heat transfer augmentation caused by the jets depends on several parameters, such as, driving frequency, driving voltage, jet axial distance, heater size, and heat flux. During the experiments, the operating frequency for the jets was varied between 3.4 and 5.4 kHz, while the driving voltage was varied between 50 and $90VRMS$. Two different heater powers, corresponding to approximately 50 and 80 °C, were tested. A square heater with a surface area of $156mm2$ was used to mimic the hot component and detailed temperature measurements were obtained with a microscopic infrared thermal imaging technique. A maximum heat transfer enhancement of approximately 10 times over natural convection was measured. The maximum measured coefficient of performance was approximately 3.25 due to the low power consumption of the synthetic jets.

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## Figures

Figure 12

Variation of the temperature rise with jet axial distance for high heat flux

Figure 13

Enhancement factor for lower heat flux case

Figure 14

Enhancement factor for higher heat flux case

Figure 10

Temperature profile under natural convection for high heat flux case

Figure 11

Heater temperature profile with the jet on (V=50V, Distance=8mm)

Figure 1

Schematic of the heater arrangement

Figure 2

Digital image of the jet side

Figure 3

Digital image of the camera side

Figure 4

IR image at high temperature

Figure 5

Transmissivity calibration

Figure 6

Typical velocity response of a synthetic jet

Figure 7

Variation of the exhaust velocity with driving voltage

Figure 8

Temperature distribution under natural convection condition for lower heat flux

Figure 9

Variation of the temperature rise with jet axial distance for low heat flux case

Figure 15

Predicted and experimental heat transfer coefficients

## Errata

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