摘要
At hydraulic structures,some strong interactions may develop between fast flowing waters and the air adjacent to the water in motion that enhance the air-water transfer of atmospheric and volatile gases in the flow.In turn,in-stream structures may contribute to the aeration and re-oxygenation during overflow.The present study aims to characterize the aeration performance of a steep stepped weir,based upon a detailed physical investigation of air-water interfacial properties across a relatively wide range of discharges.The data showed a strong fragmentation of the air-water flows,a very broad range of entrained bubbles and drops,and a large amount of particle clustering.The results implied a monotonic increase in re-aeration with increasing rate of energy dissipation,while the largest aeration efficiency was observed on the horizontal step weir chute,with the smallest on the 1V:2.33H inclined downward steps.Altogether,the study showed that a steep stepped chute can make a sizeable contribution to the re-oxygenation of the waters,although the downward inclined steps reduce the re-aeration performances.
基金
This work was supported by the Swiss National Science Foundation(Grant No.P2ELP2_181794),the School of Civil Engineering,University of Queensland.
