Team Members & Role:

• Colin DallaCosta – Team Lead
• Adam Koretsky – Design Lead
• Philip Satterthwaite – Analysis Lead
• Zachary Jordan – Fabrication Lead
• Bram Townsend – Evaluation Lead

Abstract:
Additively manufactured heat exchangers are at the forefront of design within the aerospace industry. Several of Collins Aerospace’s heat exchangers are fabricated using selective laser melting (SLM) with metal alloys, which allows for unique geometries that improve heat transfer compared to traditional plate heat exchangers. These engine heat exchangers are typically located in fuel tanks and are expected to operate for up to thirty years; however, crack propagation due to high cycle fatigue can greatly limit part life, especially when exacerbated by the stress concentrations of high surface roughness. While SLM of Inconel 718 allows for intriguing design concepts, the increased surface roughness dampens the heat exchanger’s viability over long periods. 3D-printed heat exchangers are becoming a vital component in aerospace applications because their low weight, high efficiency, and low number of manufacturing processes save producers and consumers large amounts of money in both manufacturing and operation. Collins Aerospace is currently leading the research on aluminum and titanium surface roughness improvement and has tasked this team with designing a geometry that can test surface improvement effectiveness on nickel alloys. In an effort to better understand the effects of surface roughness on such prints, the team has conducted research on currently available surface improvement techniques to apply to the sample geometry shown below. In order to evaluate these techniques, the samples will be printed on an angle in order to maximize the total surface roughness. Surface finishing methods, including electroplating or a chemical surface bath, will be employed, and the surface profile will be measured to gauge the decrease in roughness. The heat exchanger geometry will be tested to determine the effects of a lower surface roughness on total heat transfer. Additionally, these same techniques will be applied to sample dog-bone geometries which will assess the effects of high-cycle fatigue testing. This project will serve as a thorough guide to selecting the proper finishing technique for Inconel 718 heat exchangers in order to maximize part life while minimizing effects on part performance.