| High-speed discharge flow’s aeration in open channel is divided into self-aerated and force-aerated, the self-aerated flow along the line can be divided into developing region and homogeneous region. Predecessors have intensive study on the homogeneous region’s hydraulic characteristics, due to the high-speed velocity and complex air concentration, until now systematic and deep research work on the developing region is not reliable. Cavitation control by aeration is proved by a great of projects to be an important, a useful and an economical technique for preventing cavitation damage. Sometimes self-aerated can’t prevent the structure’s cavitation damage effectively, in most cases need force-aerated. Force-aerated can be divided into many kinds, in order to reduce the structure’s cavitation damage need select the appropriate aeration facilities.In order to research the self-aerated under different situations, the test adopt pressure flow and non-pressure flow, the bottom slopes are 10 degrees and 45 degrees. The article researched on the self-aerated position, flow characteristics after self-aerated, the air concentration distribution, velocity’s change rule and air concentration’s influence on velocity. To the non-pressure flow, the test set three different height aerators around the self-aerated station. To the pressure flow, the test set three different height aerators at the pressure-outlet. The test choose five degrees flow, from changing the flow and aerator’s type to analyze air concentration along the line and air concentration along the depth of water’s change rule.From comparing and analyzing the calculated value and measured value, find pressure flow and non-pressure flow have different rule with different flows, the air concentration influence the water surface’s velocity. The results of study are helpful to realize the self-aerated and force-aerator’s hydraulic characteristics under different flows and different bottom slopes.
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