A Study of an Effective Heat-Dissipating Piezoelectric Fan for High Heat Density Devices
Abstract
:1. Introduction
2. Experimental Procedures
3. Theoretical Analysis
3.1. Governing Equations
3.2. Numerical Method
4. Results and Discussion
5. Conclusions
- While the vibrating blade moves toward the neutral position, most of the streamlines released from the piezofan are dragged by the moving blade and flow back to the side surface of the piezofans for Piezofans A, B, C and D. However, this phenomenon does not occur for the contracted blade shape (Piezofan E).
- The maximum-velocity region in front of the fan tip is due to the dragged and pushed flow by the blade. Local-maximum-velocity regions at the four corners of the central region are produced by the flow released from the blade edges.
- The variation of the velocity with distance away from the tip is similar to that of a jet-like flow, but decrease more rapidly. The average velocity of the streams decays steeply within a short distance of 20 mm (δ = 1.5) from the blade tip.
- In general, a blade with a larger width has a larger velocity. The blade with a contracted shape (Piezofan E) is better for hot spot heat sources than those with divergent and rectangular shapes (Piezofans D and B).
Acknowledgments
Author Contributions
Conflicts of Interest
Nomenclature
A | amplitude of piezofan tip, mm |
ci | constant in Equations (3) and (4) |
d | distance from fan tip along the axis of the piezofan, mm |
F1,F2 | polynomials in Equations (5) and (6) |
f | first mode resonance frequency, Hz |
I | turbulence intensity, |
i,j,k | coordinate indices |
L1,L2 | length of piezofan blade, mm |
p | pressure, Pa |
ui | velocity component, m·s−1 |
Vk | velocity magnitude, m·s−1 |
average velocity magnitude, m·s−1 | |
w | width of piezofan, mm |
x,y,z | space coordinates |
α | dimensionless amplitude of piezofan, |
δ | dimensionless distance from fan tip, |
ε | turbulent dissipation rate, m2·s−3 |
κ | turbulent kinetic energy, m2·s−2 |
μ | dynamic viscosity, N s·m−2 |
density of air, kg·m−3 | |
τ | time, s |
vibration period of piezofan, s | |
ϖ | turbulent frequency (specific dissipation rate), s−1 () |
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L1 | L2 | W0 | W1 | W2 | W2/W1 | |
---|---|---|---|---|---|---|
Piezofan A | 29 | 76 | 12.7 | 12.7 | 12.7 | 1 |
Piezofan B | 19.1 | 19.1 | 1 | |||
Piezofan C | 25.4 | 25.4 | 1 | |||
Piezofan D | 12.7 | 25.4 | 2 | |||
Piezofan E | 25.4 | 12.7 | 0.5 |
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Lin, C.-N.; Jang, J.-Y.; Leu, J.-S. A Study of an Effective Heat-Dissipating Piezoelectric Fan for High Heat Density Devices. Energies 2016, 9, 610. https://doi.org/10.3390/en9080610
Lin C-N, Jang J-Y, Leu J-S. A Study of an Effective Heat-Dissipating Piezoelectric Fan for High Heat Density Devices. Energies. 2016; 9(8):610. https://doi.org/10.3390/en9080610
Chicago/Turabian StyleLin, Chien-Nan, Jiin-Yuh Jang, and Jin-Sheng Leu. 2016. "A Study of an Effective Heat-Dissipating Piezoelectric Fan for High Heat Density Devices" Energies 9, no. 8: 610. https://doi.org/10.3390/en9080610
APA StyleLin, C.-N., Jang, J.-Y., & Leu, J.-S. (2016). A Study of an Effective Heat-Dissipating Piezoelectric Fan for High Heat Density Devices. Energies, 9(8), 610. https://doi.org/10.3390/en9080610