The test article is a wedge-shaped piece of a heat-resistant metal, and it is slightly larger than a credit card. To make the cooling channels as small and efficient as possible, Sharon’s team collaborated with Collins Aerospace, an RTX business, using their expertise in micromachining, an advanced manufacturing method that uses lasers to create intricate parts.
To prove it would work, the team first tested the wedge on a burner rig at the research center in East Hartford, Connecticut.
“It’s essentially a big crème brûlée torch,” Sharon said.
The burner rig aims a torch fueled by natural gas and oxygen at the test article to mimic changes in temperature that would occur at hypersonic speeds. Once the team was confident with the test article’s performance, they conducted more intricate testing at a facility that uses an electrical arc to heat and expand gases to high temperatures and speeds, simulating the conditions of very fast flight.
The tests offered preliminary proof that their concept would work, but Sharon said they’ll need more research and refinements before transpiration cooling is ready for use in hypersonic missiles. The remaining challenges include figuring out how to make the channels even smaller, and determining whether their findings on a credit card-sized test article would scale to a full-sized hypersonic vehicle.
Sharon said he believes what they learned could have applications for several RTX products – including cooling aircraft engine turbine blades – and it showed their predictive modeling was reliable.
“When you’re flying five-plus times the speed of sound, the temperature can rise very quickly – in a fraction of a second,” Sharon said. “The folks on the team involved with modeling did an awesome job estimating how long the test article would survive.”
Finding answers to questions like this one is why Sharon joined the research center. After earning his doctorate, he saw it as an opportunity to apply cutting-edge research to aerospace and defense.
“Proving that out in the lab has been great,” he said. “The next step is always trying to say, ’How would a customer adapt this and perform better?’”
This material is based upon work supported by the United States Air Force under Contract No. United States Air Force FA8650-20-C-7001.