Industrial torch as test lab: Johns Hopkins APL screens materials for extreme heat
An ordinary thermal-spray torch reaches more than 1,980 degrees Celsius. APL researchers are using it to pre-screen materials for hypersonic and rocket technology faster.
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Video: YouTube · Johns Hopkins Applied Physics Laboratory · youtube.com
Engineers at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, have turned an industrial tool into a test stand. A high-velocity oxygen-fuel (HVOF) torch, normally used to spray coatings, produces a plume hotter than 3,600 degrees Fahrenheit – about 1,982 degrees Celsius. The team precisely characterised the conditions in the plume and reproduced them with computer models. The study was published in the Journal of Testing and Evaluation.
Using a robotic arm and simulations, the researchers determined temperature, heat transfer and aerodynamic forces, as well as speed, pressure and oxygen distribution in the plume. The result: aerodynamic loads are comparable to those of high-end ground-test facilities, and surface heating to that of a projectile re-entering Earth's atmosphere. In a first trial, four candidate materials for rocket launch systems were tested; CT scans afterwards showed how differently they responded.
The aim is to screen out promising materials early and cheaply before they go into scarce and expensive high-end test facilities. "It's not a one-to-one mapping, but high-velocity oxygen fuel is another tool in our toolbox," says team lead Gehn Ferguson. The method is already being used in the Glide Phase Interceptor program that APL manages.