Dynamic effects of piezoelectric fan on the natural convection in a vertical channel

In this study, the dynamic heat transfer characteristics of a piezoelectric fan (piezo fan) placed in a vertical channel with constant temperature side walls were investigated numerically. One of the piezo fan’s ends is fixed like a cantilever fan, and the other end performs oscillation motion at four different amplitudes and three different frequencies. The operating amplitude of the fan has been varied in such a way as to investigate the temperature distributions, pressure variations, and dynamic mechanisms of the vortices inside the channel. Numerical studies were carried out using a 2-dimensional model in the COMSOL Multiphysics software. Pure natural convection inside the channel is considered as a reference case. The piezo fan’s movement creates high-speed vortices along the flow direction, pushing them onto wall surfaces. Such complex convective mechanisms positively affect heat transfer through the hot wall. Each case’s local and average heat transfer coefficients and Nusselt numbers are compared. As a result, the piezoelectric fan operating with 12 mm amplitude and 20 Hz frequency was determined to be the most effective design with a heat transfer improvement of 169% compared to the natural convection. For the highest amplitude and frequency, the increment in the mass flow rate is up to 180%.