Numerical Study on Simultaneous Operation of Spillway and Power Intake

Run-of-river hydropower dams almost have a small reservoir and therefore, the spillway starts with the smallest flood in simultaneous with operation of power intakes. In the present study, by forming 16 vortex in different classes using Flow-3D software, the effect of simultaneous operation of spillway and power intakes in Masjed Soleyman dam and power plant was investigated. VOF method and LES model were used for simulating free surface and turbulence, respectively. Regarding the cost of calculations and the amount of error, the network size of 5 mm was selected as the appropriate mesh size. In Class A vortices when the spillway flow is at its peak, the strength of formed vortices reduced about 23%, 36%, and 68% in different intake submerged depths. The results showed that by increasing the discharge of spillway, the formed vortices were weaker. Moreover, spillway flow in Class A formed vortices did not eliminate the vortex, But it caused to change the vortex class to B and C in some cases; However, in the formed vortex of Class B and C, with simultaneous operation of the spillway and power intakes, the vortex disappear completely and rotation was not observed on the surface of the reservoir.