Experimental study on heat transfer enhancement using a flow-induced self-oscillating microfin array

Abstract

Advanced computers are facing thermal engineering challenges from both high heat generation and reduction of the available heat removal surface area. In the absence of the proper heat removal, the working temperature of electronic components may exceed the required temperature level, which in turn increases the system failure rate. Hence, the employment of a high performance computing system requires efficient and compact cooling technology to provide reliable system operation In this paper, a microfin array heat sink using the flow-induced vibration of a microfin array was experimentally investigated to quantify its effect on heat transfer enhancement in the laminar flow regime. Based on the numerical analysis of a vibrating single microfin, the heat pumping model was developed to understand the heat transfer mechanism of the microfin array heat sink. The heat transfer enhancement was considered to be possible by the rigorous mixing of the fluid resulted from the microfin vibration. Under the structural constraints and fabrication limit, the maximum heat transfer rate was obtained at the intersection of the minimum thickness of the microfin and the constraint on the bending angle. It was also determined that the maximum heat transfer rate changed with the air velocity. The quantitative characterization of the flow-induced vibration of the microfin was determined experimentally, which was totally different from the flow-induced vibration of the meso-scale structures. Due to insufficient information on the vibrating frequency and displacement, the microfin flow sensor was fabricated. The flow-induced vibration of the microfin was visually observed by using a high-speed motion analyzer. From the experimental results of the microfin flow sensor, it was determined that the microfin vibrates with the fundamental natural frequency regardless of the air velocity and the second mode vibration occurs over a certain air velocity. Also, the vibrating displacement of the m...