Recent favorable economic conditions have renewed interest in the development of low head hydroelectric projects adjacent to existing locks and dam facilities on navigable rivers within the United States. These lock facilities are typically operated by the U.S. Army Corps of Engineers (USACE). Two common concerns expressed by the USACE in adding powerhouses to such facilities are the potential project effects on sediment movement (particularly accretion) within the navigation channels both upstream and downstream of the L&D facility as well as possible adverse effects on navigation in the upstream and downstream lock approaches. The USACE generally requires physical hydraulic model studies for the purpose of developing acceptable approach and tailrace flow conditions to and from the proposed location of the powerhouse that will have minimal impact on sediment movement and navigation. The model often provides the ability to evaluate other potential project impacts including those related to fishery, other aquatic habitat, and recreational concerns.
In addition to addressing the above needs of the USACE, Alden has also used modeling to assist the power generation developer at proposed locks and dam facilities. Design of low head hydroelectric projects, particularly those utilizing horizontal bulb-type turbines involves providing approach flow conditions to the powerhouse intake conforming to turbine generator supplier’s guidelines. The integration of computational fluid dynamics (CFD) techniques with physical modeling has been an effective tool to aid in the design of approach channels and powerhouse intakes. Specifically, numerical modeling is a cost effective tool to evaluate several approach channel design alternatives and to select the best alternative to be incorporated into the physical model, which then provides validation of the numerical model and of the approach design with a time-honored method. Having the ability to use both in tandem to provide the maximum value for minimum cost and project duration is a key Alden advantage.
An example showing the use of physical and CFD modeling for both of these concerns is the Smithland Locks and Dam on the Ohio River, currently under development by American Municipal Power – Ohio, Inc. (AMP-Ohio). Alden performed physical modeling to address navigation concerns, as well as hybrid physical and CFD modeling to optimize the powerhouse approach geometry. MWH America is the owner’s engineering firm for the project.
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Velocity vectors in the approach channel colored by velocity magnitude |
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