MEASUREMENT OF CONCENTRATION DISTRIBUTION OF SELF-AERATED FLOW IN FLOOD DISCHARGE TUNNEL

摘要

In flood discharge tunnels with free flow, because of the influence of the roofs, the characteristics of self-aerated flows is different from that in the open channels. In order to test the influence of the roofs on the characteristics of self-aerated flows, the experiments on self-aerated flows in open channels and flood discharge tunnels were made and the influence of the roof on the air concentration distribution was studied. The measured results show: the air concentration decreases with the increasing height near the roof; besides, the air concentration in the water drop zone will decrease, even the maximum value of the air concentration on the vertical line may be lower than 99%. Therefore, the influence should be noticed in the calculations of the air concentration distribution, the aerated flow depth, even the air flow rate in the flood discharge tunnel with free flow.