Design-to-Manufacture Accuracy of Engineered Porosity in Additively Structures: Effect of Build Orientation

Passive porous flow-control surfaces are of interest for improving turbomachinery operability under severe conditions. However, their implementation requires accurate manufacturing of small perforations, as deviations from nominal geometries can affect the effective open area and geometrical uniformity of the porous surface. This study investigates the design-to-manufacture fidelity of additively manufactured perforated surfaces, aiming to identify manufacturing constraints and provide geometrical selection criteria for future porous inducer applications. A Latin Hypercube design was used to vary nominal hole diameter, depth, and surface porosity for circular and teardrop-shaped perforations manufactured in horizontal and vertical orientations. A complementary angular study employed a fixed geometry printed from 0° to 90° in 5° increments using titanium and Inconel. The manufactured specimens were scanned and evaluated in terms of diameter, depth, surface porosity deviation, combined RMS dimensional error, and hole-to-hole area variability. Larger circular perforations generally exhibited improved dimensional fidelity, whereas the influence of depth and porosity was more strongly coupled to geometry and orientation. The angular study revealed a material- and shape-dependent response, with circular titanium perforations showing substantial deterioration at high inclinations, while teardrop geometries exhibited a more stable response. By combining dimensional accuracy, effective surface porosity, and hole-to-hole variability, the investigation provides a more comprehensive assessment of manufacturing feasibility than individual geometrical measurements alone. The resulting findings offer practical guidance for selecting perforation geometries and manufacturing configurations, helping to reduce geometrical uncertainties before the fabrication of porous prototypes.