Development of novel tapered pin fin geometries for additive manufacturing of compact heat exchangers
Cohen, Julien Harry
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Pin fin arrays are widely used to enhance forced convection heat transfer across various industries, finding application in turbine blade trailing edges, electronics cooling, and broadly for compact heat exchange. Fin shape greatly affects flow separation and turbulence generation, and optimizing performance relies on a balance between increased heat transfer and increased pressure loss along the array. Straight circular pin fins are well-characterized in the literature, and recent works have proven more complex elliptical and teardrop cross-sectional shapes to exhibit performance enhancements in both parameters. There exist few studies in the public record on tapered circular pin fins, but these have also proven to exhibit performance enhancements. To date, no example of research has been identified for tapered, complex pin fin geometries, and although these represent an avenue for overall performance gains, manufacturing the intricate components is difficult and time-consuming using conventional machining processes. The unique and nascent capabilities of additive manufacturing now allow their economical fabrication in an increasing number of fully-dense engineering materials. This thesis compares 21 fin arrays of varying fin cross-section, taper angle, taper profile, and array pattern, separated into eight geometry families. Experimental testing was carried out on a prototype open-loop wind tunnel and corroborated with computational fluid dynamics simulations. Non-dimensional metrics were defined and used to holistically compare heat transfer efficiency, pressure loss characteristics, and overall balanced performance between fin arrays. Topics for future work and potential methods of investigation are suggested.