Hydraulic Performance of a Flexible Curtain Used for Selective Withdrawal ? A Physical Model and Prototype Comparison

by Tracy B. Vermeyen, U.S. Bureau of Reclamation, Denver, United States,
Perry L. Johnson, U.S. Bureau of Reclamation, Denver, United States,

Document Type: Proceeding Paper

Part of: Hydraulic Engineering


Reclamation (U.S. Bureau of Reclamation) studied a 1:120 scale undistorted density stratified physical model to develop a lightweight flexible curtain barrier that would control the outflow temperatures from Lewiston Lake, California. The model scale was selected to allow study of a 3000-ft length of reservoir. The reservoir topography in this reach substantially influences withdrawal layer characteristics and temperature profiles at the intake structures. Unfortunately, this scale yielded flow Reynolds numbers in the laminar to turbulent transitional range. Consequently, mixing and flow entrainment were underestimated in the model. Despite the scale effects, the model was valuable qualitative tool for evaluating various curtain designs and hydraulic responses. Based on model results, a 35-ft-deep, 1000-ft-long curtain was developed which optimized curtain and topography interaction to yield the best possible release temperature control. The curtain was installed in August 1992. Initial field monitoring confirms that design objectives were met. This paper presents model and field observed performance with a discussion of model observations that influenced the final curtain design. The paper also interprets field performance and relates differences in model findings to scaling distortions.

Subject Headings: Scale models | Hydraulic models | Temperature effects | Reservoirs | Hydraulic design | Topography | Physical models | California | United States

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