Towards Thermal-Acoustic Co-Design of Noise-Reducing Heat Sinks

Several thermal management applications involve fan-mounted heat sinks that result in fan-generated noise as an undesired by-product. These applications require noise reduction and attempt to reduce noise using separate muffler devices. However, space for separate heat-sinking and noise-reducing functionalities may be challenging in high-performance applications such as electronics cooling, data centers, automotive, aviation, and various others. A first-principles-based approach for combined heat sinking and noise reduction in the same functional volume is discussed in this paper. This paper reports on thermal-acoustic co-design of 3-D periodic porous foam structures. In order to enable a design strategy, an analytical framework that characterizes the governing performance indicators of both acoustic and thermo-fluid design on a unifying platform is laid out. A combination of analytical and phenomenological models is used to predict the absorption coefficient, transmission loss (TL), and other acoustic performance indicators. For thermal predictions, an experimentally validated semiempirical model is presented to estimate thermal resistance and static pressure drop of foam heat sink as a function of geometrical parameters as well as flow rates. Octave-band weighted values of acoustic indicators are then compared against thermal indicators to investigate thermal-acoustic co-design aspects. As hydraulic pore radius of porous foam decreases, the acoustic absorption coefficient increases reaching local maxima. Concomitantly, the pore radius decrease not only increases the absorption coefficient while dissipating heat, but also increases the heat sink pressure drop. For a chosen sound absorption region of interest, there exists a particular static pressure drop that maximizes heat sink dissipation for a given radius. The paper concludes by reporting TL and heat sink thermal performance for a generic electronics cooling configuration while elucidating the nuances of the proposed heat sink design using a thermal-acoustic index.