CavitationCavitation

By Justin LillyBy Justin Lilly

What is Cavitation?What is Cavitation?

““The sudden formation and collapse of low-The sudden formation and collapse of low-pressure bubbles in liquids by means of pressure bubbles in liquids by means of mechanical forces” – American Heritage mechanical forces” – American Heritage College DictionaryCollege Dictionary

This process usually produces a sound This process usually produces a sound when the bubbles collapsewhen the bubbles collapse

How Does it Work?How Does it Work?

Cavitation takes place when the local ambient Cavitation takes place when the local ambient pressure of the liquid falls below the vapor pressure of the liquid falls below the vapor pressure of that liquid at its local ambient pressure of that liquid at its local ambient temperature.temperature.

Props cause this to happen because of the Props cause this to happen because of the pressure changes that take place when a pressure changes that take place when a fluid flows around a solid object.fluid flows around a solid object.

Sound waves can also cause cavitation by the Sound waves can also cause cavitation by the resulting shockwave from when two resulting shockwave from when two different sources of sound collide. This different sources of sound collide. This also occurs when sound waves strike a also occurs when sound waves strike a solid object.solid object.

Where these bubbles collapse, temperatures Where these bubbles collapse, temperatures reach 5000K and pressures of the order of reach 5000K and pressures of the order of 500 to 1,000 atm have been estimated.500 to 1,000 atm have been estimated.

Beneficial Uses of Beneficial Uses of CavitationCavitation

Cavitation, when employed Cavitation, when employed in special ways, can in special ways, can aide in the following:aide in the following:

1)1) Degredation/Degredation/destruction of VOCsdestruction of VOCs

2)2) Dissolve NORMsDissolve NORMs

3)3) Cleaning/dissolution of Cleaning/dissolution of oil spillsoil spills

4)4) Killing of planktonKilling of plankton

Beneficial Uses of Beneficial Uses of Cavitation (1)Cavitation (1)

VOCs are Volatile Organic Compounds.VOCs are Volatile Organic Compounds.Benzene, Methylene, Formaldehyde are examples of VOCsBenzene, Methylene, Formaldehyde are examples of VOCs

These chemicals come from paints, varnishes, gasoline, solvents, cleaning These chemicals come from paints, varnishes, gasoline, solvents, cleaning chemicals, oil refineries, vehicle exhaustchemicals, oil refineries, vehicle exhaust

Health effects include: headaches, nausea, dizziness, cancer, liver damage, Health effects include: headaches, nausea, dizziness, cancer, liver damage, kidney damage, CNS damagekidney damage, CNS damage

Lab tests have indicated that using Acoustic Cavitation can partially degrade Lab tests have indicated that using Acoustic Cavitation can partially degrade and/or destroy VOCs.and/or destroy VOCs.

Argonne National Laboratory believes using acoustic cavitation can destroy Argonne National Laboratory believes using acoustic cavitation can destroy VOCs and petroleum hydrocarbons at a high rate with minimum contact VOCs and petroleum hydrocarbons at a high rate with minimum contact time.time.

Beneficial Uses of Beneficial Uses of Cavitation (2)Cavitation (2)

NORMS are Naturally Occuring NORMS are Naturally Occuring Radioactive Materials.Radioactive Materials.These are materials that have always These are materials that have always been present in various been present in various concentrations in the Earth’s crust.concentrations in the Earth’s crust.

Some industrial processes cause NORM Some industrial processes cause NORM to be concentrated to harmful levels.to be concentrated to harmful levels.

NORM is a carcinogen.NORM is a carcinogen.

In the study, Barium Sulfate was used as In the study, Barium Sulfate was used as the NORM tested.the NORM tested.

Using sonication, It was shown that Using sonication, It was shown that NORMs can be dissolved to a high NORMs can be dissolved to a high percentage.percentage.

Beneficial Uses of Beneficial Uses of Sonication (3)Sonication (3)

To clean oil spills, the preferred method is To clean oil spills, the preferred method is mechanical recovery. This is dependent on mechanical recovery. This is dependent on things like weatherthings like weather

The next best solution is to disperse the oil. The next best solution is to disperse the oil. Currently, dispersants are used to accomplish Currently, dispersants are used to accomplish this task. Dispersants have other undesirable this task. Dispersants have other undesirable side effects because they are toxic.side effects because they are toxic.

Beneficial Uses of Beneficial Uses of Cavitation (3)Cavitation (3)

Beneficial Uses of Beneficial Uses of Cavitation (3)Cavitation (3)

Beneficial Uses of Beneficial Uses of Cavitation (4)Cavitation (4)

Plankton in lakes and Plankton in lakes and ponds can destroy the ponds can destroy the ecological environment ecological environment there.there.

Too much plankton in an Too much plankton in an ecosystem causes a ecosystem causes a depletion of oxygen in depletion of oxygen in the body of water, which the body of water, which affects other marine affects other marine creatures.creatures.

Other Beneficial Uses of Other Beneficial Uses of CavitationCavitation

Sonic cleaners make use of acoustic cavitation Sonic cleaners make use of acoustic cavitation (sonication)(sonication)

It can be used as a non-invasive way to destroy kidney It can be used as a non-invasive way to destroy kidney stones and has been used for some time stones and has been used for some time experimentally.experimentally.

Cavitation is currently being studied as a way to get large Cavitation is currently being studied as a way to get large molecules into cellsmolecules into cells

Cavitation brought to a larger scale could be responsible Cavitation brought to a larger scale could be responsible for producing supersonic submersibles.for producing supersonic submersibles.

ConclusionsConclusions

Sonication has several beneficial uses:Sonication has several beneficial uses:1)1) Dispersion/destruction of VOCsDispersion/destruction of VOCs2)2) Dissolving of NORMsDissolving of NORMs3)3) Dissolving of oil spillsDissolving of oil spills4)4) Destruction of PlanktonDestruction of Plankton

Also, cavitation also carries the potential to do many other Also, cavitation also carries the potential to do many other things (such as kidney stone treatment and things (such as kidney stone treatment and submarines).submarines).

Sonic cleaners are currently used in labs that employ the Sonic cleaners are currently used in labs that employ the use of cavitation.use of cavitation.

ReferencesReferences

““Utilization of Cavitation for Environmental Protection – Killing Plankton and Dispersing Utilization of Cavitation for Environmental Protection – Killing Plankton and Dispersing Spilled Oil.” Hiroharu KATO, Department. Of Mechanical Engineering, Toyo Spilled Oil.” Hiroharu KATO, Department. Of Mechanical Engineering, Toyo University. 2001University. 2001

““The Use of Advanced Acoustic Cavitation for Applications in the Oil and Natural Gas The Use of Advanced Acoustic Cavitation for Applications in the Oil and Natural Gas Industry.” Michael Wilkey, Robert Peters, James Furness. Furness-Newburge, Inc Industry.” Michael Wilkey, Robert Peters, James Furness. Furness-Newburge, Inc (FNI) Versailles, KY.(FNI) Versailles, KY.

““A Brief Discussion About Naturally Occurring Radioactive Materials (NORM)” Stuart A Brief Discussion About Naturally Occurring Radioactive Materials (NORM)” Stuart Hunt and Associates Ltd.Hunt and Associates Ltd.

““Minnesota Department of Health Fact Sheet: Volatile Organic Compounds – VOCs” Minnesota Department of Health Fact Sheet: Volatile Organic Compounds – VOCs” Minnesota Department of Health Indoor Air Unit. St. Paul, MN. September 2005Minnesota Department of Health Indoor Air Unit. St. Paul, MN. September 2005

““Cavitation and Bubble Dynamics” Christopher Earls Brennen. Oxford University Press. Cavitation and Bubble Dynamics” Christopher Earls Brennen. Oxford University Press. ISBN 0-19-509409-3. 1995ISBN 0-19-509409-3. 1995

““Lithotripsy (Stone Treatment)” Center for Advanced Urology. Portland, Oregon.Lithotripsy (Stone Treatment)” Center for Advanced Urology. Portland, Oregon.

Questions?Questions?