Author(s): Chenjun Zeng, Qiuwen Chen, Jin Zhang, Yuqing Lin, Xia Hu
Linked Author(s): Qiuwen Chen
Keywords: Total dissolved gas, supersaturation, dissipation coefficient, hydraulic characteristic.
Abstract: Dam discharge is the main source for total dissolved gas (TDG) supersaturation, which may cause fishes to suffer from gas bubble disease, especially when the dissipation process of supersaturated TDG is slow. Hydraulic characteristics are important factors in the dissipation process of supersaturated TDG, the quantitative relationship between the dissipation process and hydraulic characteristic has not been previously clarified. This paper aimed to study the impacts of hydraulic characteristic on supersaturated TDG dissipation process in different conditions by using annular flume. Through a series of experiments, an equation describing the relationship between Reynolds number and dissipation coefficient was established in this study. The results showed that the supersaturated TDG dissipation coefficient increased with the Reynolds number and the flow velocity under the same water depth. When the TDG saturation was higher than 112%, the dissipation rate increased with the flow velocity. The dissipation of supersaturated TDG was dominated by the release of gas molecules which filled in the water molecule gaps in this period. When the TDG saturation was decreased down to 112%?110% or even lower, the dissipation rate appeared stable, in this situation, the dissipation of supersaturated TDG was dominated by the release of compounds which are formed by gas molecules and water molecule