UNIVERSITY PARK, Pa. — Moving through water can be a drag, but the use of supercavitation bubbles can reduce that drag and increase the speed of underwater vehicles. Sometimes these bubbles produce a bumpy ride, but now a team of engineers from Penn State Applied Research Laboratory have an approach that could smooth out the ride.
In supercavitation, a bubble of gas encompasses an underwater vehicle reducing friction drag and allowing high rates of speed through the water.
“Basically supercavitation is used to significantly reduce drag and increase the speed of bodies in water,” said Grant M. Skidmore, recent Penn State Ph.D. recipient in aerospace engineering. “However, sometimes these bodies can get locked into a pulsating mode.”
To create the bubble around a vehicle, air is introduced in the front and expands back to encase the entire object. However, sometimes the bubble will contract, allowing part of the vehicle to get wet. The periodic expansion and contraction of the bubble is known as pulsation and might cause instability.
“Shrinking and expanding is not good,” said Timothy A. Brungart, senior research associate at ARL and associate professor of acoustics.”We looked at the problem on paper first and then experimentally.”