The efficiency and mechanisms of cooling a constant heat flux surface by impinging synthetic jets were investigated experimentally and compared to cooling with continuous jets. Effects of jet formation frequency and Reynolds number at different nozzle-to-surface distances (H∕d) were investigated. High formation frequency (f=1200Hz) synthetic jets were found to remove heat better than low frequency (f=420Hz) jets for small H∕d⁠, while low frequency jets are more effective at larger H∕d⁠. Moreover, synthetic jets are about three times more effective in cooling than continuous jets at the same Reynolds number. Using particle image velocimetry, it was shown that the higher formation frequency jets are associated with breakdown and merging of vortices before they impinge on the surface. For the lower frequency jets, the wavelength between coherent structures is larger such that vortex rings impinge on the surface separately.

Issue Section:
Electronic Cooling
Keywords:
synthetic jets, impingement cooling, coherent structures, operating frequencies, large-scale mixing, jets, cooling, nozzles, laser velocimetry, flow visualisation, vortices
Topics:
Cooling, Heat, Heat transfer, Jets, Reynolds number, Vortices, Flow (Dynamics), Nozzles, Heat flux
1.
Electronics Cooling Magazine, January 2005.
2.
Martin
,
H.
, 1977, “
Heat and Mass Transfer between Impinging Gas Jets and Solid Surfaces
,”
Adv. Heat Transfer
0065-2717,
13
, pp.
1
–
60
.
3.
Nevins
,
R. G.
, and
Ball
,
H. D.
, 1961, “
Heat Transfer Between a Flat Plate and a Pulsating Impinging Jet
,”
Proc. of the National Heat Transfer Conference
,
Boulder, CO
, Vol.
60
, pp.
510
–
516
.
4.
Kataoka
,
K.
,
Suguro
,
M.
,
Degawa
,
H.
,
Maruo
,
K.
, and
Mihata
,
I.
, 1987, “
The Effect of Surface Renewal Due to Large-Scale Eddies on Jet impingement Heat Transfer
,”
Int. J. Heat Mass Transfer
0017-9310,
30
, pp.
559
–
567
.
Crossref
Search ADS
 
5.
Eibeck
,
P. A.
,
Keller
,
J. O.
,
Bramlette
,
T. T.
, and
Sailor
,
D. J.
, 1993, “
Pulse Combustion: Impinging Jet Heat Transfer Enhancement
,”
Combust. Sci. Technol.
0010-2202,
94
, pp.
147
–
165
.
Crossref
Search ADS
 
6.
Zumbrunnen
,
D. A.
, and
Aziz
,
M.
, 1993, “
Convective Heat Transfer Enhancement Due to Intermittency in an Impinging
,”
ASME J. Heat Transfer
0022-1481,
115
, pp.
91
–
97
.
Crossref
Search ADS
 
7.
Sailor
,
D. J.
,
Rohli
,
D. J.
, and
Fu
,
Q.
, 1999, “
Effect of Variable Duty Cycle Flow Pulsations on Heat Transfer Enhancement for an Impinging Air Jet
,”
Int. J. Heat Fluid Flow
0142-727X,
20
, pp.
574
–
580
.
Crossref
Search ADS
 
8.
Zulkifli
,
R.
,
Benard
,
E.
,
Raghunathan
,
S.
, and
Linton
,
A.
, 2004, “
Effect of Pulse Jet Frequency on Impingement Heat Transfer
,” AIAA Paper No. 2004–1343.
9.
Hwang
,
S. D.
,
Lee
,
C. H.
, and
Cho
,
H. H.
, 2001, “
Heat Transfer and Flow Structures in Axisymmetric Impinging Jet Controlled by Vortex Pairing
,”
Int. J. Heat Fluid Flow
0142-727X,
22
, pp.
293
–
300
.
Crossref
Search ADS
 
10.
Hwang
,
S. D.
, and
Cho
,
H. H.
, 2002, “
Effects of Acoustic Excitation Positions on Heat Transfer and Flow in Axisymmetric Impinging Jet: Main Jet Excitation and Shear Layer Excitation
,”
Int. J. Heat Fluid Flow
0142-727X,
24
, pp.
199
–
209
.
Crossref
Search ADS
 
11.
Chaniotis
,
A. K.
,
Poulikakos
,
D.
, and
Ventikos
,
Y.
, 2003, “
Dual Pulsating Slot Jet Cooling of a Constant Flux Surface
,”
ASME J. Heat Transfer
0022-1481,
125
, pp.
575
–
586
.
Crossref
Search ADS
 
12.
Haneda
,
Y.
,
Tsuchiya
,
Y.
,
Nakabe
,
K.
, and
Suzuki
,
K.
, 1998, “
Enhancement of Impinging Jet Heat Transfer by Making Use of Mechano-Fluid Interactive Flow Oscillation
,”
Int. J. Heat Fluid Flow
0142-727X,
19
, pp.
115
–
124
.
Crossref
Search ADS
 
13.
Camci
,
C.
, and
Herr
,
F.
, 2002, “
Forced Convection Heat Transfer Enhancement Using a Self-Oscillating Impinging Planar Jet
,”
ASME J. Heat Transfer
0022-1481,
124
, pp.
770
–
782
.
Crossref
Search ADS
 
14.
Vukasinovic
,
J.
, and
Glezer
,
A.
, 2001, “
An Active Radial Countercurrent Heat Sink
,”
Proceedings of IMECE 2001: 2001 International Mechanical Engineering Congress and Exposition
, EEP-6AI-2.
15.
Kercher
,
D. S.
,
Lee
,
J.-B.
,
Brand
,
O.
,
Allen
,
M. G.
, and
Glezer
,
A.
, 2003, “
Microjet Cooling Devices for Thermal Management of Electronics
,”
J. Chem. Theory Comput.
1549-9618,
26
(
2
), pp.
359
–
366
.
16.
Mahalingam
,
R.
,
Rumigny
,
N.
, and
Glezer
,
A.
, 2004, “
Thermal Management Using Synthetic Jet Ejectors
,”
J. Chem. Theory Comput.
1549-9618,
27
(
3
), pp.
439
–
444
.
17.
Incorpera
,
F. P.
, and
DeWitt
,
D. P.
, 1996,
Fundamentals of Heat and Mass Transfer
, 4th ed.,
Wiley
,
New York
, p.
171
.
18.
Smith
,
B.
, and
Glezer
,
A.
, 1998, “
The Formation and Evolution of Synthetic Jets
,”
Phys. Fluids
1070-6631,
31
, pp.
2281
–
2297
.
19.
Kline
,
S. J.
, and
McClintock
,
F. A.
, 1953, “
Describing Uncertainties in Single Sample Experiments
,”
Mech. Eng. (Am. Soc. Mech. Eng.)
0025-6501,
75
, pp.
3
–
8
.
20.
Smith
,
B. L.
, and
Swift
,
G. W.
, 2001, “
Synthetic Jets at Large Reynolds Numbers and Comparison to Continuous Jets
,”
AIAA J.
0001-1452 Paper No. 2001–3030.
Copyright © 2006
 by American Society of Mechanical Engineers
You do not currently have access to this content.