Investigation of the effects of aerators in reducing cavitation damage on spillways using two-phase numerical modeling

One of the most critical challenges in ensuring the safety and performance of dams is cavitation damage occurring in spillways, which are among the most vital structural components of dams. The spillway of the Gelevard-Neka Dam, located in Mazandaran Province, Iran, is potentially susceptible to cavitation. In this study, a two-phase air-water numerical model was developed using FLOW-3D software to simulate flow conditions in the Gelevard-Neka spillway. Based on the simulation results, five cavitation damage risk levels were identified along the spillway. At locations where the flow velocity exceeded 15 m/s, the cavitation damage was classified as major. Aerators were subsequently designed according to these risk levels, incorporating a combination of ramps, offsets, grooves, and duct aerators. Four scenarios were evaluated, and the results demonstrated that the best scenario-incorporating four aerator systems-significantly improved cavitation damage mitigation. The cavitation number increased by approximately 70%, and the maximum air concentration reached 0.868. Furthermore, the damage levels were successfully reclassified, ranging from major damage to no damage, while the maximum velocity decreased from 33 m/s to 19 m/s.