Martin Wosnik
St. Anthony Falls Laboratory
University of Minnesota
 
Friday, December 3
319 Akerman Hall
3:30-4:30 p.m.
 
 
Cavitation Research at St. Anthony Falls Laboratory
 
An overview of current cavitation research at St. Anthony Falls Laboratory (SAFL), University of Minnesota, will be given. 
 
Cavitation is defined as the formation of the vapor phase in a liquid, and will occur in any device handling liquids at sufficiently high velocities or low pressures. It can have negative effects on the performance of 
turbomachinery, limit the thrust of propulsion systems and degrade the accuracy of fluid meters.  Noise and vibration occur in many applications, and there is the possibility of cavitation erosion. In contrast to these
 undesirable effects, sometimes cavitation is useful. Examples are ultrasonic cleaning, homogenization of milk, enhancement of chemical processes and sonochemical reactions, increase of heat and mass transfer in
 liquids and the potential for high-speed drag reduction. Biomedical applications include the removal of kidney stones and automated drug delivery. Recently, cavitation has also been applied in pollution control.
 
Our current research at SAFL includes high speed supercavitating vehicles, boundary layer drag reduction by injection of microbubbles, novel low-drag partially cavitating ventilated hydrofoils, fundamental 
investigations into the sheet/cloud cavitation mechanism on lifting surfaces, and cavitation erosion in geomorphology. Most of our research projects are set up as integrated experimental/numerical studies. The
principal experimental facility is the high speed water tunnel at SAFL, a recirculating closed-jet facility capable in excess of 20 m/s. Experimental tools include various kinds of pressure transducers and
hydrophones, force balances and optical methods (high-speed photography and cinematography, PIV, LDV, PDA). The numerical work is based on a virtual single-phase, fully compressible cavitation model
coupled with a Large-Eddy Simulation (LES) approach, which is capable of capturing the complex dynamical features of highly unsteady cavitating flows. Our research is supported by NSF, DARPA, ONR,
MSI.