Alden has developed a new hydraulic turbine runner to reduce fish injury and mortality at hydroelectric projects. The new runner was developed as part of the Advanced Hydropower Turbine Project sponsored by the U.S. Department of Energy (DOE). The first phase of the project utilized three-dimensional computational Fluid Dynamic (CFD) analysis to define a unique turbine runner that met established criteria for safe fish passage while achieving hydraulic power efficiency comparable to other turbines. The second phase of the program was pilot-scale testing to quantify the effect of fish passing through the runner and verify the basic hydraulic performance of the turbine.
A pilot-scale turbine test facility was designed by Alden engineers and fisheries biologist and constructed at Alden. The closed loop facility has a 2,000 HP pump, fish injection system, pilot-scale turbine, and fish collection system. The pilot-scale turbine included a scroll case, wicket gates, runner, shaft dynamometer, and draft tube.
Engineering and biological tests were conducted with the 1:3.25 scale pilot turbine with and without the wicket gates. Preliminary tests without the gates indicated that the measured best efficiency point (BEP) was 86% with 93 cfs at 80 ft head and 345 rpm. The measured BEP was slightly less than the BEP predicted with the CFD model (89% with 95 cfs at 80 ft head and 325 rpm). Tests with rainbow trout indicated that the handling and holding procedures minimized fish injury and mortality and no statistical difference in survival of rainbow trout released in the bottom, middle, and bottom of the turbine inlet pipe. Tests with rainbow trout indicated 83-93% survival rates after 96 hours depending on the fish length and turbine test speed and head.
Preliminary tests with the wicket gates indicated that the measured BEP was at a gate setting of 18º from fully closed, about 4º more closed than the original CFD predicted gate position of 22º. The measured BEP with the gates was 86.5% with 84 cfs at 80 ft head and 345 rpm. Tests with three sizes of rainbow trout confirmed that survival rates were related to fish size and turbine rotation speed/head condition. Wicket gate tests results with the rainbow trout were statistically similar to the results without the wicket gate indicating that wicket gates do not contribute to turbine passage survival.
Testing with other species and the turbine operating at 240 rpm (40 ft head) indicated 90-100% survival, similar to rainbow trout survival for the same turbine operating set points. Off-BEP tests with rainbow trout indicated no statistical difference in fish survival over the 10º range of wicket gate positions evaluated.
Results of the pilot-scale tests indicate that fish survival through the full size prototype turbine would be 94-100% depending on the fish length. The full sized turbine would have a 90.5% maximum efficiency.
Prototype studies are being planned for a hydroelectric site. Contact gallen@aldenlab.com for more information.
