Abstract
Adequate design of energy dissipation structures is essential for effective flood control. The effect of aeration on water flow has been one of most analyzed phenomena during the last decades due to its influence on hydraulic structures. The purpose of this study is to characterize the influence of aeration on the boundary friction in supercritical and fully turbulent flows. Our analysis is based on a physical model to reproduce these phenomena and consists of a spillway chute 6.5 m high, followed by a 10 m length and 2 m high still basin. Water and air are supplied by a pump and compressors, and is controlled at the entrance by several valves and flowmeters, while the channel is monitored to measure the velocity profile and air concentration in the intake flow to the still basin. Velocity results included in this paper show the relation between air concentration and energy dissipation by friction. To determine this relation, Manning roughness numbers have been obtained for all scenarios. It has been found that greater air entrainment implies acceleration of the flow, since friction is the main energy dissipation mechanism in open channels flow.
Highlights
The social and economic impact of floods represents a very important issue due to the enormous amounts of losses involved
Dams play a crucial role to match the requirements for hydrological regulation against flooding phenomena, especially in basins with extreme hydrological regimes. This is the reason why hydraulic and dam operation requirements need to cope with increasing safety standards, and future dam technical regulation should include the need for higher levels of dam operation control and safety devices, as well as higher discharge capacities
Results obtained during the experimental phase show that, in a constant water flow, there is a velocity increase with aeration growth
Summary
The social and economic impact of floods represents a very important issue due to the enormous amounts of losses involved In this context, dams play a crucial role to match the requirements for hydrological regulation against flooding phenomena, especially in basins with extreme hydrological regimes. Dams play a crucial role to match the requirements for hydrological regulation against flooding phenomena, especially in basins with extreme hydrological regimes This is the reason why hydraulic and dam operation requirements need to cope with increasing safety standards, and future dam technical regulation should include the need for higher levels of dam operation control and safety devices, as well as higher discharge capacities. The Hydraulic Laboratory of CEDEX (Spain) is carrying out an experimental study of the aeration influence over chutes and stilling basins in the framework of the Proceedings 2019, 7, 5; doi:10.3390/ECWS-3-05812 www.mdpi.com/journal/proceedings
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