An analysis of turbulent effects on hydrokinetic power generation

Thesis (M.S.) University of Alaska Fairbanks, 2022The effects of turbulence on power generation from a Current Energy Converter (CEC) are not fully understood. This thesis investigates the correlation between a vertical axis CEC's power output and the water velocity in the frequency and time domains. Chapter 2 shows the correlation between velocity and electrical power in frequency space. This correlation gives insight into the size of eddies that influence the CEC's power output. The results of this correlation analysis show that eddies of diameter around 0.8m have a noticeable impact on the power generation. Calculating the observed average integral length scale, the range of eddy diameters around the CEC are 0.52m-5.8m. Since 0.8m is in this observed range it suggests that the turbulence may influence the CEC's power output. Chapter 3 analyzes the relationship between the turbulence velocity cubed and electrical power through the correlation of the two data sets. The correlation was carried out by first separating out the four velocity components derived from cubing the sum of the turbulence and average velocities. The commonly used ratio of the turbulence kinetic energy to total kinetic energy does not include these cross terms nor are these cross terms typically included in the calculation of power derived from the turbulence velocity. The turbulence velocity cubed has a correlation of -0.007 with the CEC power output indicating that the turbulence has a small, negative impact on the CEC power output.Alaska State Legislature Finance Committee through the "ACEP Partnership to Development Statewide Energy Solutions." U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE) under the Water Power Technologies Office Award Number DE-EE0008389, “Water Horse Hydroelectric Harvester Development.”Chapter 1: Introduction -- 1.1. Current energy converter designs -- 1.2. Microgrids -- 1.3. Alaska rivers -- 1.4. Tanana River test site -- 1.5. Debris -- 1.6. Fisheries -- 1.7. Effects of ice on CECs -- 1.8. Seasonal river flow changes -- 1.9. Summary -- 1.10. Work cited. Chapter 2: Efficiency Analysis of a New Energy 5 kw CEC in an Alaska Environment -- 2.1. Abstract -- 2.2. Introduction -- 2.3. Methods -- 2.4. Results -- 2.5. Discussion -- 2.6. Conclusion -- 2.7. Work Cited. Chapter 3: A time series and spectral analysis of turbulence effects on current energy converter power generation -- 3.1. Introduction -- 3.2. Methods -- 3.3. Results -- 3.4. Discussion -- 3.5. Conclusion -- 3.6. Work cited. Chapter 4: General conclusions -- 4.1. Eddy size -- 4.2. Cross terms -- 4.3. Future work -- 4.4. Conclusion