Aeration and deaeration at bottom aeration devices on spillways

Abstract

Aeration devices are introduced along chute spillways and at bottom outlets to prevent cavitation damage in high velocity flows. Bottom aerators are characterized by large quantities of air entrained along the jet interfaces and also by a strong deaeration process near the impact of the water jet with the spillway bottom. In this paper, the aeration and deaeration occurring respectively in the aeration region and in the impact region are reviewed. A reanalysis of air concentration data obtained on models provides information on the flow characteristics at the end of the impact region. These results enable an accurate initialization of the downstream flow calculations using the method developed by Chanson. Key words: bottom aeration devices, aerators, spillways, air entrainment, detrainment.