Abstract Additive manufacturing is now a mainstream technology and can be utilized to rapidly develop and test turbine airfoil cooling networks. This paper reports on an ongoing effort to integrate advanced internal cooling architectures in a realistic blade profile. The airfoils are currently being tested in a highspeed cascade. It is important to note that the cooling architectures are developed for small industrial gas turbines, but the results could be applied to larger frame engines. In the present study, various 1x-scale coupons were printed with features from the cascade airfoils (i.e., orifices, pin fin arrays, and converging trailing edge sections). Cold flow test results are presented for four orifice shapes (circular, raindrop, 2:1 elliptical, and 3:1 elliptical), and high and low solidity pin fin arrays. In addition, flow test results are reported for both metal and plastic test articles representing three different trailing edge designs. For the orifices, the elliptical shapes had the least deviation from design intent and the highest discharge coefficients. The friction factors for pin fin arrays were higher than both existing correlations and data available in the literature. The difference is attributed to the high roughness of the 80 μm build layer height utilized to reduce fabrication time. The trailing edges included three different geometries for pin fin arrays (ranked in order of increasing friction factor): 45° angled pin fins, horizontal pin fins supported with chamfers, and horizontal pin fins supported with a novel “gusset” feature. The ratio of the friction factor for the metal coupons to the plastic coupons is approximately equal to the friction factor augmentation resulting from the metal roughness alone. The friction factor augmentation was similar for each design despite the different geometries, varying from 1.5 to 2. The results obtained here may be utilized to advise future studies and internal cooling designs.
Searle et al. (Mon,) studied this question.