Author(s): Zhiqun Deng; Gregory R. Guensch; Marshall C. Richmond; Mark A. Weiland; Thomas J. Carlson

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Keywords: Prototype measurement; pressure fluctuation; stilling basin; pressure spectra; fish injury

Abstract: At The Dalles Dam on the Columbia River, fish are believed to sustain injury from exposure to turbulence and from collisions with baffle blocks and end sills in the stilling basin at high spillway discharges. Because taking velocity measurements would be exceedingly difficult in this environment, a system of pressure transducers was installed to record high-frequency pressure data for a range of spillway discharges. The sensors were mounted below two of the spillbays on the tops, faces, and sides of baffle blocks; in the gaps between baffle blocks; and on the top and face of the end sill. Statistical analyses on results from three sensors below one of the two spillways showed that mean pressure increased during head-on flow, decreased in flow separation zones, and was proportional to water depth. Power spectra indicate increased low-frequency spectral power with increased discharge, typical spectral decay rates, and the existence of spectral peaks of possible hydraulic origin. The high-frequency pressure data collected at full scale in extremely turbulent environments will contribute to efforts to improve fish passage and to develop and validate three-dimensional computational fluid dynamics models.

DOI: https://doi.org/10.1080/00221686.2007.9521803

Year: 2007