Alden Research Laboratory, Inc. (Alden) has completed pilot scale testing of the new Alden/Concepts NREC turbine that was designed to minimize fish injury at hydropower projects. The test program was part of the U.S. Department of Energy’s (DOE) Advanced Hydropower Turbine Systems Program. The prototype turbine operating point was 1,000 cfs at 80 ft head and 100 rpm. The turbine was designed to: 1) limit peripheral runner speed; 2)have a high minimum pressure; 3) limit pressure change rates; 4) limit the maximum flow shear; 5) minimize the number and total length of leading blade edges; 6) maximize the distance between the runner inlet and the wicket gates and minimize clearances (i.e., gaps) between other components; 7)maximize the size of flow passages.
A pilot scale facility was designed and constructed to test a 1:3.25 reduced scale turbine with and without wicket gates. The test loop was operated at flows ranging between 50-95 cfs and 35-85 ft heads and the pilot scale turbine was operated at speeds ranging between 200-375 rpm to determine the Best Efficiency Point (BEP) over the range of wicket gate positions. Engineering tests were conducted to define the turbine BEP speed and head/flow combinations without and with wicket gates. Biological testing was conducted to evaluate turbine passage survival relative to: 1) fish injection location at the turbine inlet; 2) size of fish; 3) species; 4) high and low turbine speed/head/flow conditions; 5) BEP with and without wicket gates, and; 6) off-BEP wicket gate positions.
A final CFD analysis was completed as part of the pilot scale study to investigate the turbine flow patterns at off-BEP wicket gate positions for comparison to the flow patterns at the BEP gate position and observed fish injury at the different gate settings. The pilot scale test results indicate that the Alden/Concepts NREC turbine has the potential to pass fish at hydroelectric projects with minimal injury and mortality.
