Validation of a 3D RANS model to predict flow and stratification effects related to fish passage at hydropower dams

Abstract

This paper discusses the validation and application of a three-dimensional RANS model to simulate flow and temperature distributions within the powerhouse units and the forebay of McNary Dam on the Columbia River. The hydrodynamic model is first validated with data collected from an experimental model study of a single turbine intake unit. The capability of the model to predict stratification effects is then investigated by comparing the predicted temperature field with field data collected within the forebay of McNary Dam. It is found that the model is able to accurately predict the salient features of the thermally stratified flow within the forebay for a test case corresponding to strongly stratified conditions without spill and for a case corresponding to moderately stratified conditions with spill. The model is then applied to investigate the effects of introducing a floating curtain wall in the forebay on the gatewell temperatures at the 14 powerhouse units of the dam. It is found that one of the designs appears to alleviate the occurrence of adverse thermal conditions within the gatewells and fish collection channel

Keywords:

• RANS model
• thermally stratified flow
• fish passage
• hydropower dams