High power light emitting diodes (LEDs) being used for low and high beam in automotive lighting need active cooling of their heat sinks by radial or axial fans. But the moving elements of the fan cause abrasion, noise, and high energy consumption. Synthetic jets can replace conventional fans with their disadvantages and allow the directed cooling of LEDs. Therefore, in this paper, flow and heat transfer characteristics of impinging synthetic jets are investigated numerically and experimentally as an alternative to cooling LEDs with fans. It is shown that the impact plate brings forward the laminar-turbulent transition of the jets temporally and spatially. The impact plate itself should not be positioned in the region of the free jet's transition height. Increasing the frequency of the synthetic jet has a greater influence on the heat transfer compared to an increase in amplitude. The maximum cooling performance is achieved for all jet configurations with moderate distances between the orifice and the impact plate. In this case, the jet reaches its highest mass flow and impulse and its lowest temperature.

References

References
1.
Khanh
,
T. Q.
,
2008
, LED-Technik - Anwendungen, praktische Experimente,
FG Lichttechnik, TU Darmstadt
,
Darmstadt, Germany
.
2.
Smith
,
B. L.
, and
Swift
,
G. W.
,
2003
, “
A Comparison Between Synthetic Jets and Continuous Jets
,”
Exp. Fluids
,
34
(
4
), pp.
467
472
.
3.
Qayoum
,
A.
,
Gupta
,
V.
,
Panigrahi
,
P. K.
, and
Muralidhar
,
K.
,
2010
, “
Influence of Amplitude and Frequency Modulation on Flow Created by a Synthetic Jet Actuator
,”
Sens. Actuators A
,
162
(
1
), pp.
36
50
.
4.
VDI
,
2006
, “
VDI-Gesellschaft Verfahrenstechnik und Chemieingenieurwesen
,”
VDI-Waermeatlas
,
10th ed.
,
Springer-Verlag
,
Berlin
, pp.
53
82
.
5.
Ingard
,
U.
, and
Labate
,
S.
,
1950
, “
Acoustic Circulation Effects and the Nonlinear Impedance of Orifices
,”
J. Acoust. Soc. Am.
,
22
(
2
), pp.
211
218
.
6.
Garcillan
,
L.
,
Zhong
,
S.
,
Pokusevski
,
Z.
, and
Wood
,
N. J.
,
2004
, “
A PIV Study of Synthetic Jets With Different Orifice Shape and Orientation
,”
AIAA
Paper No. 2004-2213.
7.
Mallinson
,
S. G.
,
Reizes
,
J. A.
,
Hong
,
G.
, and
Westbury
,
P. S.
,
2004
, “
Analysis of Hot-Wire Anemometry Data Obtained in a Synthetic Jet Flow
,”
Exp. Therm. Fluid Sci.
,
28
(
4
), pp.
265
272
.
8.
Pavlova
,
A.
, and
Amitay
,
M.
,
2006
, “
Electronic Cooling Using Synthetic Jet Impingement
,”
ASME J. Heat Transfer
,
128
(
9
), pp.
897
907
.
9.
Valiorgue
,
P.
,
Persoons
,
T.
,
McGuinn
,
A.
, and
Murray
,
D. B.
,
2009
, “
Heat Transfer Mechanisms in an Impinging Synthetic Jet for a Small Jet-to-Surface Spacing
,”
Exp. Therm. Fluid Sci.
,
33
(
4
), pp.
597
603
.
10.
Qayoum
,
A.
,
Gupta
,
V.
,
Panigrahi
,
P. K.
, and
Muralidhar
,
K.
,
2010
, “
Perturbation of a Laminar Boundary Layer by a Synthetic Jet for Heat Transfer Enhancement
,”
Int. J. Heat Mass Transfer
,
53
(
23–24
), pp.
5035
5057
.
11.
Lee
,
A.
,
Timchenko
,
V.
,
Yeoh
,
G. H.
, and
Reizes
,
J. A.
,
2012
, “
Three-Dimensional Modelling of Fluid Flow and Heat Transfer in Micro-Channels With Synthetic Jet
,”
Int. J. Heat Mass Transfer
,
55
(
1–3
), pp.
198
213
.
12.
Gillespie
,
M. B.
,
Black
,
W. Z.
,
Rinehart
,
C.
, and
Glezer
,
A.
,
2006
, “
Local Convective Heat Transfer From a Constant Heat Flux Flat Plate Cooled by Synthetic Air Jets
,”
ASME J. Heat Transfer
,
128
(
10
), pp.
990
1000
.
13.
Derlien
,
H.
,
2012
, “
Synthetische jets zur kuehlung von punktuellen waermequellen - experimentelle untersuchung des stroemungsverhaltens und dessen einfluss auf die kuehlleistung
,” Diploma thesis, FAU Erlangen-Nuremberg, Erlangen, Germany.
14.
Ferziger
,
J. H.
, and
Peric
,
M.
,
2008
,
Numerische Stroemungsmechanik
,
Springer-Verlag
,
Berlin
.
15.
Tsinober
,
A.
,
2009
, “
An Informal Conceptual Introduction to Turbulence
,”
Fluid Mechanics and Its Applications
, Vol.
92
,
Springer
,
Dordrecht, The Netherlands
.
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