Introduction to Cavitation

Why Study Cavitation? Has been an important topic in engineering science for well over 100 years. Any device handling liquids is subject to cavitation. Can adversely affect the performance of turbomachinery, the thrust of propulsion systems and the accuracy of fluid meters. Noise, vibration and erosion occur in many applications

Why Study Cavitation? Important in applications such as ultrasonic cleaning, homogenization of milk, enhanced chemical processes through coagulation, formation of suspensions and degassing of liquids. Cavitation can be used to increase heat and mass transfer in liquids, to promote crystallization and to enhance various sonochemical reactions such as polymerization and polymer degradation.

Why Study Cavitation? Biomedical applications include the removal of kidney stones and automated drug delivery to patients. Important new applications in the pollution control area are of interest. Plays a role in biomechanics, geomorphology and other topics in physics.

Cavitation in Biophysics From SCIENCE VOL 289 22 SEPTEMBER 2000

Spillway Damage Due to a Horseshoe Vortex

Vortex Damage in a Hydroturbine

Geomorphology See Movie

Cavitation Can Occur in the Flow or Adjacent to a Boundary On the surface of a Hydrofoil Jet Flow

Fundamentals The fundamental parameter in describing the physics of the process is the cavitation index, defined by   We can think of i as a performance boundary such that    > i no cavitation effects    < i cavitation effects such as performance degradation, noise, and vibration

US Navy Large Cavitation Channel Water Tunnels US Navy Large Cavitation Channel 3m X 3mTest Section 10 Stories High SAFL Water Tunnel 0.19m X 0.19 m Test Section 1 Story High

Propeller Cavitation Japan The Netherlands PIV Imaging, Italy Comparison of measurements with numerical simulations,USA PIV Imaging, Italy

Tip Vortex Cavitation Wind tunnel and water tunnel simulations are used to study this problem experimentally. Experiments are supplemented with numerical simulations. Example shown is a NACA 662-415 section with elliptic planform. Wind tunnel Water tunnel

Observation of Singing Vortex Slow Motion, 4500 fps Pressure Slowly Decreasing

Supercavitating Vehicles A joint venture between SAFL and AEM AEM: Stability and Control SAFL: Physics of Ventilated Flows Sponsored by ONR

Ventilated Flow Studies- Supercavitation

looking for new applications The Future We are always looking for new applications

For Further Information: http://www.safl.umn.edu