Cavitation Risk through the Bottom Outlet of the Dam Using Numerical Solution of Ansys Model

The objective of the present research was to investigate the flow properties through the bottom outlet of the Nesa dam based on numerical and experimental studies. 22 piezometers were employed to measure the static pressure through the experimental model. The bottom outlet section was divided into three blocks to measure the endangered region. The graph of cavitation numbers was plotted for different flow discharge and cavitation damage levels to compare with a safe zone to find out the areas with a high risk of cavitation. The results illustrate that block No. 1 cavitation index is located at the “possible cavitation” damage. The studies showed that the cavitation index is the dependent parameter with the height of the water at the upstream reservoir. Furthermore, for block No. 2, the level of cavitation ranged from x/L = 0.44 to 0.90 and the cavitation level is related to the velocity, and by increasing the velocity to 16 m/s, the threat of the cavitation and its consequences is raised, dramatically. Regarding block No.2 and 3, the cavitation through this block depends on the negative pressure since the negative values of the cavitation index is related to the negative static pressure and it is assumed that the negative pressure can reach the threat of major damage. Also, a comparison between different numerical turbulence models illustrates that the k-ε RNG with fine mesh showed less error with experimental values which causing the numerical model with this condition to reach an appropriate agreement between numerical and experimental simulations.