Penstock Air Vent Analysis

Project ID: 5710
Principal Investigator: Josh Mortensen
Research Topic: Public and Employee Safety
Priority Area Assignments: 2015 (Renewable Energy and Energy Conservation)
Funded Fiscal Years: 2015
Keywords: air demand, air venting, aging infrastructure, emergency gate closure, penstock

Research Question

How does a hydraulic jump or falling water surface in a penstock during an emergency gate closure influence the total air demand required to protect the penstock?

During an emergency gate closure, the water remaining in the penstock continues to flow and creates a void in the pipe starting directly downstream of the gate. Vents allow air to fill this void preventing excessive negative pressures which may cause irregular gate operation and even collapse of the penstock in some cases. It is essential that these vents are properly sized to allow sufficient air flow. Under-sized or inadequate air vents pose a threat to the safety of the facility, personnel, and the public. This issue has become a greater concern for many facilities as the infrastructure gets older and operations are modified.

Need and Benefit

The need for more confidence in air vent analyses, especially for marginal cases, becomes more prevalent as our infrastructure ages. A significant benefit of the proposed study will be that the improved analytical methods will be widely applicable throughout Reclamation. It will reduce the need for site specific studies and testing. By conducting physical laboratory testing under a range of operational conditions and configurations, results from both current and past studies can be combined to optimize an analytical method that can be applied to a range of air venting systems for hydropower penstocks and dam outlet works.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Products will include updated analytical methods to be used for predicting air demand and air vent sizing required for emergency operations of penstocks and other outlet works. A Hydraulic Laboratory Report will also be submitted documenting findings.

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Last Updated: 6/22/20