Guzman de la Rosa, Javier2024-02-092024-02-092023https://hdl.handle.net/11299/260609University of Minnesota M.S.M.E. thesis.--- 2023. Major: Mechanical Engineering. Advisor: Craig Hill Hill. 1 computer file (PDF); viii, 65 pages.Power performance and turbulent wake characteristics of a scaled current-driven marine turbine were simulated using unsteady 3D RANS with the k-ω SST turbulence model and sliding mesh technique. The turbine is an axial flow, dual rotor tidal turbine with counter-rotating rotors, each with two blades and a diameter of d_T = 0.5 m, representing an approximately 1:40 scale system based on the U.S. Department of Energy’s Reference Model 1 (RM1) tidal turbine. Validation of numerical results for three tip speed ratios was performed by comparison with experimental data. The influence of rotor cross-stream spacing on power production was also studied by modeling three distinct lateral rotor separations, equal to 1.2d_T, 1.4d_T, and 1.6d_T. Numerical results showed a good correlation ranging within ±3.8% of turbine performance to experimental measurements for all tip-speed ratios studied, validating the numerical results for power estimation and demonstrating the advantages of this model when dealing with high-flow detachment. Inflow dynamics were captured well, exhibiting a difference of less than 5% compared to experimental data. However, wake dynamics showed a significant difference between numerical results and experimental data, ranging from 16% error at approximately 〖X/d〗_T=4, up to 170% error at 〖X/d〗_T=8. Finally, numerical results indicated a tendency for higher power production as the rotors are spaced farther apart, with the resulting power coefficient values of C_p = 0.449, 0.461, and 0483 for lateral rotor spacings of 1.2d_T, 1.4d_T, and 1.6d_T, respectively. This behavior was accredited to the reduction of the flow through the swept area of the rotors, causing what is known as 'choking effect’.esComputational Fluid Dynamics (CFD)Reference Model 1Renewable EnergyTidal energyThesis or Dissertation