ABSTRACT
The dissipater with jets collision before entering the plunge pool is often used and efficient for the flood discharge and energy dissipation in a high-arch dam with surface spillways and mid-level outlets. However, the collision of jets in air often results in strong atomization, which can cause landslides and slope instability and affect the ecological environment. In this study, the contracted dissipaters, such as flaring gate piers and slit-type buckets, were adopted for the surface spillways and mid-level outlets in a high arch dam to achieve energy dissipation without jets collision in air. Then experiments were conducted to study the flow regime, atomization, and hydrodynamic pressure on the slab of the plunge pool. The comparison between the collision and non-collision dissipaters showed that the contracted dissipaters could avoid the jets collision in air, so that the rainfall intensity of atomization was reduced greatly; it also indicated that the hydrodynamic pressure and fluctuation pressure on the plunge pool slab caused by jets impacting could be effectively decreased with the contracted dissipaters. This study proves that the case of jets non-collision energy dissipation is feasible and can provide a good alternative for flood discharge and energy dissipation for high-arch dams in narrow valleys where strong atomization should be avoided.
