KEEPING C L WORDS: Sam Davies
W
hat do the wings of a butterfly, the feathers of a bird, the retinal cone cells of a tree shew, and this helicopter heat exchanger all have in common?
It’s the use of gyroid structures to help flight, sight and, in the case of the aluminum component printed on an EOS M 290 machine, the optimal cooling of a helicopter gearbox. At least, that’s the hope for Andreas Vlahinos, CTO of Advanced Engineering Solutions, who is currently seeing his TCT Award-nominated design go through a qualification process for use on commercial helicopters. Gyroids are a triply periodic morphology with no planes of symmetry, no embedded straight lines, and well suited to parts that need strength without too much weight. The heat exchanger developed by Vlahinos has an internal volume that is filled with gyroid structures which encourage uniform cross flow throughout the piece to cool the gearbox. Using lattice screens at the end of the internal gyroid domain has also helped to eliminate the need for support structures inside the component, while external lattice ribs minimize the shell thickness requirement. With the input of these design characteristics, the heat exchanger is said to exhibit 4x better performance than the original design, is around half the size and has an enhanced fatigue life since it is manufactured in a single component as opposed to several brazed together pieces. “The traditional design of these heat exchangers, they call it shell and tube and there is a bunch of components brazed together,” Vlahinos told TCT. “Brazing thin components is not good for fatigue life because there’s a lot of vibration in the helicopter, so you need to keep monitoring the fatigue life of the heat exchanger and it’s dangerous because fuel goes through it, and you don’t want them to mix. This one is very robust because it doesn’t have any welded parts. In the testing, the design was 300 PSI and we went to 5,000 PSI to break it, so there’s a lot of margin.”
020 / www.tctmagazine.com / VOL 8 ISSUE 3
SHOWN: HELICOPTER HEAT EXCHANGER DESIGNED WITH INTERNAL GYROID LATTICE STRUCTURES
