Alden turbines

Consideration of environmental criteria and standards aimed at minimizing the negative impact of turbines on the state of the environment is becoming one of the basic principles used in the selection of hydropower equipment. The greatest damage is done to fish populations. The variability of pressure, velocity and stress conditions, as well as sudden changes in the shape and geometry of the channels through which fish flow, reduce their chances of survival.

The trajectory that a fish must follow as it moves from an upstream to a downstream position contains a number of factors that negatively affect its condition. There are areas of sudden increases and decreases in pressure, areas of cavitation, areas where fish are exposed to abrasion, impact, shearing, crushing and turbulence. The Alden Turbine is one of the few where in designing its shape an effort was made to consider the environmental requirements established by (Cook et al. 1997 and Franke et al. 1997). The criteria are as follows:

– rotor circumferential velocities should be less than or equal to 12 m/s,

– minimum rotor pressure should not be less than 69 kPa,

– the rate of change of pressure in the rotor should be less than 550 kPa/s,