École polytechnique fédérale de Lausanne EPFL:
CAVITATION BUBBLES IN VARIABLE GRAVITY
Cavitation – the appearance of vapour bubbles in a liquid as the pressure drops (similarly to boiling) – occurs naturally in many hydraulic systems. The violent collapse of such bubbles engender serious erosion damage in propulsion systems, rocket-propellers and energy-production turbines, but also has a potential for useful applications in water cleaning and medicine, for instance.
Cavitation erosion is thought to be associated with energetic events occurring at the last instants of the bubble collapse, in particular with high-speed liquid jets and high-pressure shock waves emitted during the violent collapse of these bubbles. The cavity even concentrates its energy so as to reach temperatures of thousands of degrees, inducing an emission of light.
In our parabolic flight experiment we studied the energetic phenomena exhibited by the most spherical bubble ever created in order to unravel the physical laws governing cavitation erosion in hydraulic systems on Earth. For more information, please see: bubbles.epfl.ch
Contact: Dr. Mohamed Farhat, Head of Cavitation Research Group, EPFL-LMH, Lausanne, Switzerland, email: Mohamed.Farhat@epfl.ch