| Summary: | 碩士 === 國立高雄應用科技大學 === 模具工程系 === 99 === The features of electronic component are “light”, “thin”, “short”, and “small” is the global trend. Because of the characteristics of piezoelectric fan are small size, ultralight, simple structure, and sensitive response, it is suitable for cooling application in miniaturization electronic components.
This study is to explore the flow phenomena of velocity vector, streamline and velocity profile of strategic position when piezoelectric fan works under different forms of heat sink by changing the piezoelectric fan height which is relative to five different heat sinks. It used flow visualization technique (PIV System), driven by 110V, 60Hz and fix the range of amplitude and the distance (0.5 mm) between blade tip and fin. To examine the piezoelectric fan flow phenomena with non-fin, single fin, end-slotting, middle-end slotting and center-slotting and end-slotting plate-fin heat sink.
The empirical results show that when blade is moved downward from the top, the counterclockwise vortex occurs at the tip. Oppositely, the clockwise vortex occurs when blade is moved upward from the bottom. Under the dynamic compression, the jet-like flow occurs at the tip. Besides, the induced flow occurs at the boundary of jet flow when piezoelectric fan works with single fin, but not easy occurs with multi-fin. As piezoelectric fan works with multi-fin and set at the middle, the amplitude cover most of heat sink, so that jet-like flow cover heat sink mostly. From the velocity profile of heat sink strategic position, the smallest velocity gap between jet-like flow upstream and downstream is happened when use non-slotting heat sink. Moreover, due to the slotting position on heat sink, momentum will loss at downstream of flow and makes the velocity gap greater than non-slotting heat fin.
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