Designing Turbine Improvements for Safe Fish Passage

摘要

The US Army Corps of Engineers' (COE) Walla Walla District intends to replace arnfailing turbine unit at the Ice Harbor Lock and Dam. The goal of replacing the new runner alongrnwith other turbine modifications will be to improve the hydraulic conditions for safer fish passage.rnHowever, design criteria for safe fish passage are not well developed nor are the tools forrnevaluating designs in regards to safe fish passage; therefore, the COE is pursuing a new designrnand procurement process that will allow the COE to work with a manufacture to develop andrnevaluate turbine design improvements that would be implemented with a new runner designed forrnsafe fish passage.rnThe COE Turbine Survival Program has been working to develop operational and designrncriteria for over a decade and is developing several tools in the endeavor. Therefore, the COErnhas elected to work directly with a turbine manufacturer in the design of the runner and otherrnmodifications. The areas of focus for improvement include decreasing: the probability of fishrnstriking the stay vanes, wicket gates, and runner blades; sheer, and turbulence throughout thernwater pathway; and the pressure change experienced through the runner. In addition to thernperformance modeling typically used in runner design, design alternatives will be evaluated usingrna 1:25 clear acrylic physical model, and computational fluid dynamics modeling. The clear acrylicrnmodel allows general observations of flows but also Laser Doppler Velocimeter measurements ofrnvelocities, flow distributions, and turbulence. The model is also used to observe neutrally buoyantrnbeads, with the aid of high speed video, to estimate the potential for fish striking structure andrnencountering sheer while passing the turbine. The Computational Fluid Dynamics modeling willrnbe used to estimate the pressure history fish could experience in passing the runner. Preliminaryrndata suggest that fish passing through pressure nadirs of <9 – 12 psia could be fatal, dependingrnon many other factors.rnThe contractor and the COE will develop alternatives and assess them with the toolsrndiscussed above. We expect many refinements and iterations in the process. The final designrnwill likely include modifications to the stay vanes and draft tube in addition to the new runner.rnOnce the modifications are made and the new runner installed, we will conduct field studies torndocument the survival and injury rates of fish passing the unit. If this Project is successful inrnmeeting the goal of working collaboratively with a turbine manufacturer to design a turbine saferrnfor fish this approach will likely be adopted for future turbine rehabilitations or replacements of allrnFCRPS dams on the lower Snake River and lower Columbia River.