why new fish-friendly turbine designs are a vital part of hydro’s
future. The U.S. Department of Energy’s Advanced Hydropower Turbine
System program has identified specific injury mechanisms, which include:
flows or cavitation in turbine water passages resulting from
low-efficiency designs or plant operating strategies where extremely
low water pressures cause the formation of vapor bubbles, which
subsequently collapse violently.
flows and the trapping and cutting of fish in the zone of flow passing
near the turbine hub when large gaps between blade and hub exist
(characterizing the lower-output operation of Kaplan turbines).
of fish by turbine blades or impact of fish on structures including
runner blades, stay vanes, wicket gates, and draft tube piers.
stress when two bodies of water of different velocities collide across
a fish’s body. The highest values of shear stress are found close to
the interface between the flow and solid objects it speeds by, such as
the blade leading edges, vanes, and gates.
and extreme pressure changes (water pressures within the turbine may
increase to several times atmospheric pressure, then drop to
sub-atmospheric pressure, all in a matter of seconds).
and grinding: Abrasion occurs with the rubbing action of a fish against
rough turbine surfaces by flow turbulence and is dependent on flow
discharge and velocity, number and spacing of turbine blades, and the
geometry of flow passages. Grinding injury can occur when a fish is
drawn into small clearances (gaps of sizes close to that of the fish)
within the turbine system.
Maybe we could be of some help? Let’s find somebody interested in ‘fish-turbulence’ interactions.