The Effect of a Piezoelectric Fan on Forced Air Heat Transfer in a Pin-Fin Heat Sink

An investigation was carried out on the effect of airflow from the blade of a piezoelectric fan on the main cooling airflow across a pin-fin heat sink. The study considered the respective orientation and distances between the piezoelectric blade and the heat sink in a rectangular channel where the airflow was uniform and axial. Three different pin-fin heat sinks with in-line pin-fin arrays were used: 5x5, 7x7 and 9x9. Variable parameters included the Reynolds number of the main airflow and the relative position of the piezoelectric blade and the heat sink. The results showed that the smaller the horizontal distance between the blade and the heat sink, or the greater the vertical distance between the piezoelectric blade and the channel floor, the better the total heat transfer enhancement. Of the three heat sinks used, the 9x9 unit coupled with transverse oscillation of the piezoelectric blade had a slightly higher heat-transfer ratio enhancement. The heat-transfer enhancement ratio Nu/Nu(0) (Nu(0) is the Nusselt number of the system without the piezoelectric blade) will gradually approach 1 with an increase of the Reynolds number of the main flow. At Re-L=1200, and with the assistance of the piezoelectric blade, the maximum value of Nu/Nu(0) for the 9. 9 pin-fin heat sink exceeded 2.