Model Development of a Fish Electromechanical Barrier for Hydraulic Turbines

Abstract

The fish access into the draft tube of hydraulic turbines has caused numerous ecological accidents in several Brazilian hydropower plants. Many Brazilian fish species usually swim upstream for spawning and are attracted by the flow coming from the turbine tailrace pipe into the hydraulic machine. Some technical alternatives have been evaluated as feasible solutions to impede the fish entrance into hydraulic turbines. Electromechanical fish barriers appear to be a promising alternative to repel fishes from hydraulic turbine due to their small impact on the turbine flow and due to their capability of efficiently impeding the entrance of aquatic living beings into the turbine draft tube. This paper presents the development of a reduced model of an electromechanical barrier, designed to be installed on the draft tube stoplog guides, that is intended to impede the fish upstream movement through the turbine. A model of an axial-flow propeller turbine, at scale of 1:10.5, is specially designed for this work. The turbine test bench includes the turbine spiral case and draft tube, the turbine runner and the afterbay tank, which has been built to accommodate the fish individuals tested in this work. The efficacy tests of the electromechanical barrier model are performed at several operating conditions. The fish movement near the barrier is monitored by using small video cameras, which permit to record and to observe the fish reaction under the effect of electrical fields at the entrance of the turbine draft tube.