A CFD Model to Evaluate the Effect of Sluiceway Deflectors on the Hydrodynamics and TDG Field in the Tailrace of Hells Canyon Dam

摘要

A computational fluid dynamics (CFD) study was performed to evaluate the effect of installing spillway deflectors in the tailrace of Hells Canyon Dam (HCD). Free surface simulations were carried out to predict spillway jet regimes with and without deflectors. Model results were compared against deflector performance curves from a 1: 48 scale model. Through a Lagrangian particle tracking technique, accelerations, strain rate and pressure change rate were calculated to estimate the possibility of fish injury due to the inclusion of the deflectors. According to the model results, changes on the flow field caused by deflectors do not pose a major threat to fish survival. A two-phase flow model for prediction of Total Dissolved Gas (TDG) was also validated to evaluate possible gas bubble disease in fish. The model takes into account the attenuation of the turbulence at the free-surface and the effect of the bubbles on the turbulence. Bubble diameter changes due to dissolution and pressure. Predicted TDG values matched field measurements with a deviation of +/- 3%. Future work will use the TDG model to analyze changes in TDG due to the inclusion of deflectors.