The use of additive manufacturing (AM) processes, such as direct metal laser sintering (DMLS), provides the design freedom required to incorporate complex internal cooling schemes in gas turbine components. Additively produced components, such as turbine blades, would expect to include a range of feature sizes in the internal channels and cooling holes. As AM is used to produce a turbine airfoil, there are numerous relative build angles that are inherent to the component, which is three-dimensional in nature. Previous studies have shown build direction influences internal surface roughness which augments heat transfer and pressure loss performance. However, the effect of varying channel size across multiple build directions has not thoroughly been investigated for cooling performance and channel tolerances. This study investigates the impact of feature size and build direction on tolerances, surface roughness, and performance. Multiple coupons were made from Inconel 718 with a 40-micron layer size consisting of channels with different hydraulic diameters and a variety of build directions. Significant variations in surface roughness and geometric deviations from design intent were observed at distinct build directions and channel sizes. These differences led to notable impacts in friction factor and Nusselt number augmentations which were observed in the experimental test.


Impact of Additive Manufacturing on Internal Cooling Channels With Varying Diameters and Build Directions

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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