Author(s): Marcela Politano, Ran Li
Keywords: Total dissolved gas; Air entrainment; Bubble dissolution;
Abstract: One environmental concern of hydropower is the supersaturation of total dissolved gas (TDG), which may induce gas bubble disease in affected fish. The main source of TDG downstream of dams is the dissolution of bubbles entrained during spill events. Current two-phase flow models predict TDG based on an Eulerian approach with the entrained gas volume fraction and bubble size as model parameters. These parameters are typically calibrated against TDG measurements downstream of the dam. In this study, a mechanistic model is used to compute the air entrained in the spillway. The model was implemented in the open source code OpenFOAM. Preliminary results in a single spillway bay of Tongjiezi dam in the Dadu River in China show that the model is able to reproduce the observed TDG during a spill event with the bubble size at the entrainment region as the only parameter.