Efficient approaches to reduce cavitation damage risk in the bottom outlet: Case study of Seymareh dam

The occurrence of the cavitation phenomenon in hydraulic structures operating
under high flow velocities remains a critical challenge. Efficient mitigation
strategies may include increasing air concentration and optimizing the
geometric design, such as minimizing sharp changes in flow direction and
reducing local vortices. The Seymareh dam bottom outlet, operating under
high water heads, is prone to cavitation due to its velocity and pressure fields.
This study numerically investigates the effects of geometric modifications on
cavitation risk reduction. Results showed that removing lateral expansion
increases cavitation indices on outlet walls, while designing a concave curved
bed elevates pressure and cavitation indices on the bed surface. Nonetheless,
implementing both modifications together completely suppresses cavitation
risk. The numerical analysis was conducted under single-phase flow
conditions, without considering air entrainment, which, in practice, could
further improve outlet safety. These findings could provide useful insights for
geometric design approaches to control cavitation in high-velocity hydraulic
structures.