Improved Methods for Air Demand Analysis and Air Vent Sizing for Hydraulic Structures
Reclamation currently does not have a generally applicable method for air demand analysis and air vent sizing. While algorithms exist for predicting air demand during otulet works emergency gate closures (Reclamation Engineering Monograph 41: Air-Water Flow in Hydraulic Structures), little has been done in the past 20 years to update and improve the existing methods using presently available computational techniques. This Science and Technology (S&T) Program research project is intended to improve methods for determination of air demand and hence optimize air vent sizing requirements using a commercially available Computational Fluid Dynamics (CFD) code.
Need and Benefit
The frequency of requests from Reclamation designers and field offices for air demand analyses and air vent size requirements applicable to emergency gate closures has been on the increase in the last several years, due primarily to more frequent rehabilitation and modification of existing Reclamation facilities. Generally, such requests are limited to existing outlet works facilities undergoing rehabilitation or found to have oversized air vents. Present analytical methods are at best approximate and overly conservative for complicated structures, particularly in cases where venting is required during turbine wicket gate failure. Although Reclamation has developed generalized algorithms as described in Reclamation's Engineering Monograph No. 41, little has been done to maintain such capability within Reclamation--neither from an expertise nor a computational methods perspective. Nevertheless, current CFD capabilities are considerably more advanced and should be well suited for air demand applications. The primary needs include:
* Improved methods for predicting air demand during emergency closures, particularly when downstream turbine control is involved
* Demonstrated application of CFD methods for air demand prediction
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