For When We Return Home: Reverse-Engineering and Examining the Kaplan Turbine Performance in the Vardnilhesi Hydro Power Plant Cascade in Abkhazia, Georgia

Abstract

The current thesis studies the performance of Vardnilhesi -2, 3, 4 Hydro Power Plants in Abkhazia, Georgia, in the face of regular seismicity in the region. Motivated by Georgia's goal of becoming more energy independent, the Vardnilhesi HPP Kaplan turbine performance was evaluated under seismic loading in a laboratory setting to enhance HPP's technical groundwork. A reverse-engineered Kaplan turbine geometry was determined, scaled to 5%, and manufactured for testing. An experimental seismicity cage was also designed and manufactured to serve as a testing foundation, as well as a fully replicable methodology and data analysis tools. The experiment evaluated the rotational behavior of the manufactured turbine for two water flow speeds and seismic frequencies in the (0, 2) hz range. Two key findings were observed for the higher water flow speed. Firstly, (i) with an increase in the shaker input frequency (stronger earthquakes), the turbine rotational frequency first decreased, then increased over a larger range of values, and finally dropped again. Two peaks were observed at shaking frequencies of approximately 0.9-1.0 hz, and 1.6-1.7 hz, respectively. Secondly, (ii) for shaker frequencies below 1.2-1.4 hz, turbine slowing was observed compared to the original no-earthquake rotational speed; for shaking above this range, the turbine grew faster. Two hypotheses were proposed and examined to explain this behavior, inspired by the unsteady sailing studies: (i) an instantaneous change in the flow speed direction and magnitude, and (ii) advantageous vortex creation at certain frequencies downstream of the turbine. Recommendations for future work were developed.