Hydrodynamic performance of additively manufactured minichannels

Additive manufacturing can be used to fabricate components with complex flow channels for a variety of applications. Examples includes minichannels through with fluids flows for heat transfer applications. However, an efficient design of such systems requires a deep understanding of the thermal and hydrodynamic performance on channel surfaces. Of particular interests are cross section configuration and surface roughness of additively manufactured metallic flow channels. In this study, hydrodynamic performance of minichannels is evaluated by measuring pressure drop across the channel as air is supplied at designated flow rates. The gas pressure drop is measured across the channel and the friction factor is obtained as a function of the Reynolds number. Experiments were conducted for flow channels with different cross sectional geometries while they were designed with equal cross-sectional area. The friction factor obtained for all flow channels were greater than the laminar flow theory for smooth channels which indicates an elevated surface roughness feature across the channel. Among the channels tested, the rectangular flow channel with an aspect ratio of 3:1 resulted in highest friction factor values. In addition to pressure drop measurements, micrographs of channels were taken and qualitatively compared with their original CAD design. The comparison revealed that the fabricated flow channels were smaller than their CAD design. For the square flow channel, the deviation between the manufactured flow channel profile and the CAD model was quantitatively compared. Results indicated that the average deviation for this coupons was less than 100 μm.