Session: Poster Session

Paper Number: 162742

Investigating the Performance of Additively Manufactured Channels in Laminar Flows 

Increasing heat loads generated by high-power compact electronics on aircrafts requires improving air-cooled heat exchanger capabilities, especially for operation in rugged environments. To reduce fan operation costs, some electronics applications cannot tolerate high pressure drops, so that methods for mixing low Reynolds number flows are needed to improve heat transfer. One common way of enhancing cooling is turbulence promoters, such as ribs. Additive manufacturing (AM) expands the design space for these turbulence promoters, but inherent surface roughness and deviation from design intent can affect performance. This study investigates how roughness affects the performance of turbulators enabled through AM with a focus on laminar and transitional flows. Two different turbulator geometries were selected based on performance measured in previous studies: broken wavy ribs and diamond pyramids. For each type of turbulator, test coupons were manufactured with varying turbulator spacings and heights. In addition, aspect ratio effects were evaluated using three empty duct coupons. Test coupons were characterized using computed tomography (CT) scans and optical profilometry. Findings show that decreasing spacings between pyramids had the greatest effect on performance in laminar flows. However, decreasing spanwise spacings between broken wavy ribs has limited effectiveness. By increasing turbulator height, heat transfer was significantly enhanced in broken wavy rib channels for low Reynolds number flows, while pyramids experienced relatively little enhancement. Roughness led to early transition to turbulence, and augmentation of heat transfer and friction factor compared to laminar correlations. Overall, broken wavy ribs have higher efficiencies than diamond pyramids in laminar flows.

Presenting Author: Abbigail Altland Pennsylvania State University

Presenting Author Biography: Abbigail Altland is a Ph.D. student at the Pennsylvania State University where she conducts research at the Steady Thermal Aero Research Turbine (START) Laboratory. She also received her bachelor’s degree at the Pennsylvania State University during which she worked as a member of the Zhu Group studying day-time radiative cooling. In her current research, she focuses on the development of additively manufactured cooling geometries with applications in gas turbine engines and heat exchangers.

Authors:

Abbigail Altland Pennsylvania State University
Stephen Lynch Pennsylvania State University
Karen Thole Pennsylvania State University
Robert Pearson Lockheed Martin
Kevin Birchenough Lockheed Martin