Air entrainments by vortices at water surfaces inside surface intake facilities of electrical power plants cause some problems, such as deterioration of power generation, destruction of blade in a turbine, etc. To suppress air entrainments by the vortices, some vortex-preventing devices have been proposed and have been used in many electrical power plants. The vortex-preventing devices used in the intake facilities are working effectively in many cases. However, the hydraulic properties of flow structure by the vortex-preventing devices are still unclear.
In this paper, the effects of the vortex-preventing devices in surface intake facilities have been investigated experimentally by using the particle tracking velocimetry. The results show that the vortex-preventing devices suppress the turbulent intensity and the vorticity inside the facility.