Effect of the building orientation on additively manufactured copper alloy: Hydraulic performance of different surface roughness channels

The additive manufacturing capabilities open new frontiers in the design of complex geometries in many different application fields, especially thermal science, in which multi-functional, efficient, compact components with internal cooling or heating channels are becoming more and more requested. Among the possible additive manufacturing technologies, the laser powder bed fusion process has recently been proven to manufacture high-conductivity metals, with good mechanical and thermal properties (i.e. pure copper and copper alloys), attracting the attention of the heat transfer community. However, depending on the material, design, and process parameters, the surface roughness of the components can remarkably change and become a critical issue in cooling applications. Currently, the surface texture characteristics and the final channel size cannot be accurately estimated a priori, and thus the initial hypothesis of the current design methods may lead to unpredictable and undesired results. This work experimentally and numerically explores the effects of the building orientation on the fluid dynamic behaviour in CuCrZr alloy channels, which is considered one of the most promising additive manufacturing materials for thermal applications. By coupling the experimental hydraulic results with surface characterization and X-ray computer tomography dimensional measurements of the channels, a novel simplified methodology to properly correlate the pressure drop to the surface texture of a single wall is proposed and numerically validated.