Safety Alert: Model Can Cut Cavitation

Wednesday, November 17, 2010 @ 03:11 PM gHale

Under certain conditions, bubbles can wreck havoc on and industrial process.
This cavitation, created under certain conditions where vapor bubbles can form and collapse with such great force they can poke holes in steel objects like turbine blades, nozzles and pump impellers.
There is now a new set of experiments aimed at preventing cavitation damage in jet fuel pumps, essential components in aircraft, according to a group led by Notre Dame professors Patrick Dunn and Flint Thomas.
The experiments show great differences in cavitation behavior between water and JP-8 jet fuel, which is a complex mixture of more than 228 hydrocarbons and additives, each with its own fluid properties.
While it can clean jewelry and disintegrate kidney stones, cavitation is can be a big safety concern for manufacturers.
“Improved jet-fuel pumps are needed particularly for military aircraft being designed to fly at higher altitudes and in other demanding environments,” Dunn said. “But manufacturers still rely heavily upon trial-and-error in design. If they were confident that a computer-designed pump would work as predicted, new pumps could be lighter, more efficient and have longer lifetimes.”
The Notre Dame research provides jet-fuel pump designers with the first realistic data they can use in their computer models to make better predictions of vulnerable locations in their pumps and systems where cavitation bubbles occur and then collapse.
It’s difficult to model cavitation in pumps because the fluid typically has a turbulent journey with accelerated flows though small channels, orifices, and spinning discs, Dunn said. With so many constituents, jet fuel is also a computer modeler’s nightmare. Its properties can even change with storage conditions and often ends up contaminated with microparticles that can promote cavitation.

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