Effect of Side and Tip Gaps of a Piezoelectric Fan on Microelectronic Cooling

A combination of experimental and numerical analyses is conducted to investigate the coupled effect of side gap (Gs) and tip gap (δ) on the performance of a piezoelectric fan in microelectronic cooling. Two parallel adjustable walls are set at the fan sides to facilitate the variation of Gs. The piezoelectric fan is oriented vertically to the heat source (chip). A 3-D simulation using FLUENT 6.3.2 is performed to assess the transient flow and the resulting heat transfer from the chip. The coupled effect of Gs and δ on the fan tip deflection is detected by a laser displacement sensor (KEYENCE LK-G152). Both Gs and δ had noticeable effects on the flow behavior and Re. The effect of δ is more significant on the heat-transfer coefficient than that of Gs. The flow profiles and the temperature contours are found to be consistent with each other, and the predictions are in good agreement with the experimental results. The piezoelectric fan enhances the heat-transfer coefficient 1.95 to 2.7 times, corresponding to the best and worst cases, respectively.