Assessing hydraulic conditions through Francis turbines using an autonomous sensor device

Abstract

Fish can be injured or killed during turbine passage. This paper reports the first in-situ evaluation of hydraulic conditions that fish experienced during passage through Francis turbines using an autonomous sensor device at Arrowrock, Cougar, and Detroit Dams. Among different turbine passage regions, most of the severe events occurred in the stay vane/wicket gate and the runner regions. In the stay vane/wicket gate region, almost all severe events were collisions. In the runner region, both severe collisions and severe shear events occurred. At Cougar Dam, at least 50% fewer releases experienced severe collisions in the runner region operating at peak efficiency than at the minimum and maximum opening, indicating the wicket gate opening could affect hydraulic conditions in the runner region. A higher percentage of releases experienced severe events in the runner region when passing through the Francis turbines than through an advanced hydropower Kaplan turbine (AHT) at Wanapum Dam. The nadir pressures of the three Francis turbines were more than 50% lower than those of the AHT. The three Francis turbines had much higher magnitudes and rates of pressure change than the AHT. This study provides critical information on hydraulic conditions and fish passage information of Francis turbines, which can help guide future laboratory studies of fish passing through Francis turbine, design fish-friendly turbines, and optimize the operation of existing turbines for better fish passage conditions.