Heat transfer enhancement analysis of a cylindrical surface by a piezoelectric fan

Piezoelectric fans consist of a thin flexible blade attached to a vibrating piezoelectric patch, and provide an effective means of enhancing the heat transfer in low convective regions. In this study, the characteristics of the three-dimensional heat and fluid flow fields generated by the vibrating fan are examined by performing numerical simulations and experimental measurements. In performing the simulations, the fluid domain is discretized using a dynamic meshing scheme to take account of the time-varying shape and position of the vibrating blade. The results show that two counter-rotating screw-type flow structures on either side of the blade appeared on either edge of the blade, and a pair of asymmetric vortex is formed around the fan tip. The experiment is conducted with a total of eighteen T-type thermocouples attaching to the cylindrical surface to measure the variation of temperature. The experimental and numerical results indicate that the piezoelectric fan improves the heat transfer coefficient by 1.2–2.4 times. Moreover, the augmentation of local heat transfer coefficient can be achieved by 2.85 times.