Cavitation: Difference between revisions

Latest revision as of 19:02, 11 July 2023

Learn more about the dangers of cavitation at DamFailures.org

"Cavitation damage is initiated by spillway flows over a defect along the flow surface. The defect creates localized negative pressures within the flow which create vapor bubbles. Individual vapor bubbles converge and form larger vapor cavities. When the vapor cavities impact the flow surface they implode and generate large forces which damage the flow surface. Cavitation generally requires long flow durations (weeks or months) to produce significant damage. The potential for cavitation damage to initiate can be predicted with the cavitation index, which is a function of the flow velocity, the pressure along the flow surface and the vapor pressure of water." ^[1]

Examples

Learn more about the damage that was caused by cavitation at Glen Canyon Dam (DamFailures.org)

Best Practices Resources

Design Standards No. 14: Appurtenant Structures for Dams (Ch. 3: General Spillway Design Considerations), USBR

Hydraulic Design of Spillways (EM 1110-2-1603), USACE

Cavitation in Chutes and Spillways (EM 42), USBR

Trainings

On-Demand Webinar: Intro to Cavitation in Chutes and Spillways

On-Demand Webinar: Designing Spillways to Mitigate Failure Modes

Citations:

↑ Lesson Learned: Concrete-lined spillways are vulnerable to significant damage and potential reservoir breach if flows are not safely contained within the conveyance structure, William Fiedler, ASDSO, 2022

Revision ID: 7124
Revision Date: 07/11/2023

[DForg-1] Lesson Learned: Concrete-lined spillways are vulnerable to significant damage and potential reservoir breach if flows are not safely contained within the conveyance structure, William Fiedler, ASDSO, 2022

[1]

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 <!-- Introductory paragraph or topic page summary -->
-"Cavitation damage is initiated by spillway flows over a defect along the flow surface. The defect creates localized negative pressures within the flow which create vapor bubbles. Individual vapor bubbles converge and form larger vapor cavities. When the vapor cavities impact the flow surface they implode and generate large forces which damage the flow surface. Cavitation generally requires long flow durations (weeks or months) to produce significant damage. The potential for cavitation damage to initiate can be predicted with the cavitation index, which is a function of the flow velocity, the pressure along the flow surface and the vapor pressure of water. A case history of extensive damage to the spillway [[lining]] and foundation due to cavitation is the Glen Canyon Dam Spillway (see Best Practices: Reclamation and USACE 2019). Ball milling is a [[mechanism]] in which cobble and gravel sized material is introduced into a hydraulic jump stilling basin and remains in place. The trapped material is caught in a cyclical flow pattern that abrades the concrete surface. Significant concrete damage can occur, but it takes very long durations." <ref name="DForg">[https://damfailures.org/lessons-learned/concrete-lined-spillways-are-vulnerable/ | Lesson Learned: Concrete-lined spillways are vulnerable to significant damage and potential reservoir breach if flows are not safely contained within the conveyance structure, William Fiedler, ASDSO, 2022]]</ref>
+"Cavitation damage is initiated by spillway flows over a defect along the flow surface. The defect creates localized negative pressures within the flow which create vapor bubbles. Individual vapor bubbles converge and form larger vapor cavities. When the vapor cavities impact the flow surface they implode and generate large forces which damage the flow surface. Cavitation generally requires long flow durations (weeks or months) to produce significant damage. The potential for cavitation damage to initiate can be predicted with the cavitation index, which is a function of the flow velocity, the pressure along the flow surface and the vapor pressure of water." <ref name="DForg">[https://damfailures.org/lessons-learned/concrete-lined-spillways-are-vulnerable/ Lesson Learned: Concrete-lined spillways are vulnerable to significant damage and potential reservoir breach if flows are not safely contained within the conveyance structure, William Fiedler, ASDSO, 2022]</ref>
 ==Examples==
@@ Line 17: / Line 17: @@
 ==Best Practices Resources==
-{{Document Icon}} [[Hydraulic Design of Spillways (EM 1110-2-1603)|Hydraulic Design of Spillways (EM 1110-2-1603) (U.S. Army Corps of Engineers)]]
+{{Document Icon}} [[Design Standards No. 14: Appurtenant Structures for Dams (Ch. 3: General Spillway Design Considerations) | Design Standards No. 14: Appurtenant Structures for Dams (Ch. 3: General Spillway Design Considerations), USBR]]
-{{Document Icon}} [[Design Standards No. 14: Appurtenant Structures for Dams (Ch. 3: General Spillway Design Considerations)|Design Standards No. 14: Appurtenant Structures for Dams (Ch. 3: General Spillway Design Considerations) (Bureau of Reclamation)]]
+{{Document Icon}} [[Hydraulic Design of Spillways (EM 1110-2-1603) | Hydraulic Design of Spillways (EM 1110-2-1603), USACE]]
-{{Document Icon}} [[Cavitation in Chutes and Spillways (EM 42)|Cavitation in Chutes and Spillways (EM 42) (Bureau of Reclamation)]]
+{{Document Icon}} [[Cavitation in Chutes and Spillways (EM 42) | Cavitation in Chutes and Spillways (EM 42), USBR]]
 ==Trainings==