Development and evaluation of a new helical fish-friendly hydroturbine

A new hydroturbine was developed to improve fish survival during their downstream migration. This turbine includes a normal scroll case, few but relatively long wicket gates, a streamlined downturn before the runner inlet, a runner with only three helical blades attached to a tapered hub and a rotating shroud attached to the outside edges of the blades. After design of the turbine using analytical methods and construction of a 1:3.25 scale pilot turbine and flow loop, engineering studies and tests with live fish were conducted at full-scale heads and velocities. Resulting test data indicated that the full-scale turbine would have an efficiency of about 90% and that fish survival would be about 98% for fish 100 mm (4 in.) long. Survival would be greater for smaller fish and less for larger fish. Various improvements to the turbine design were identified prior to full-scale field application.