Mechanisms for improving fin heat dissipation through the oscillatory airflow induced by vibrating blades

•The inherent mechanism of vibrating fans cooling a fin heat sink is investigated.•The pulsating flow field generated by the vibrating fan is analyzed numerically.•An optimized fan blade with trapezoidal and grooved structures is developed.•The trapezoidal-folding blade relieves the maximum temperature by 7.5 °C. The vibrating fan is one of the promising candidates to alleviate the thermal failure of electronic devices, while its coupling mechanism in actual applications is not clear yet. In this work, the heat dissipation of vibrating fans was experimentally examined, and its inherent mechanism was demonstrated through the comparison between steady and pulsating flows based on numerical simulation. Firstly, the flow fields induced by the vibrating blades exhibit pulsating features, but the localized velocity magnitude is much higher than the pulsating flow. Besides, the large-scale vortical structures are first formed at the blade tip and then squeezed by the fins into various small-scale vortices flowing into the channels. Thus, the heat dissipation is significantly improved. Secondly, the impacts of different blade structures are identified. The trapezoidal structure can drive more airflow due to its large swept area, and the grooved structure can benefit the formation of small-scale vortices. Then, the trapezoidal-folding blade is developed as a combination of trapezoidal and grooved structures. It is found that the trapezoidal-folding blade can decrease the maximum temperature of the heat source by 7.5 °C compared to the traditional steady flow condition, which can effectively alleviate the high-temperature failure crisis.