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Ocean Systems Engineering
  Volume 5, Number 2, June 2015, pages 125-138

Performance prediction of horizontal axis marine current turbines
Sakir Bal, Mehmet Atlar and Deniz Usar

    In this study, hydrodynamic performance of a 400 mm diameter horizontal axis marine current turbine model was tested in a cavitation tunnel with 1.21 m x 0.8 m cross-section for over a range of tip speed ratios. Torque and thrust data, as well as cavitation visualizations, for certain operating conditions were acquired. Experimental results indicated that the turbine can be exposed to significant amount of sheet and cloud cavitation over the blades along with vortex cavitation at the blade tips. Inception and distribution of cavitation along the blades of the model turbine were then modelled numerically for design operating conditions using a vortex lattice method. The method was also applied to a turbine tested previously and obtained results were compared with the data available. The comparison between simulation results and experimental data showed a slight difference in terms of span-wise extent of the cavitation region. The cloud and tip vortex cavity observed in experiments cannot be modelled due to the fact that the VLM lacks the ability to predict such types of cavitation. Notwithstanding, the use of such prediction methods can provide a reasonably accurate approach to estimate, therefore take the hydrodynamic effects of cavitation into account in design and analysis of marine current turbines.
Key Words
    marine current turbine; cavitation; vortex lattice method
Sakir Bal and Deniz Usar: Department of Naval Architecture and Marine Engineering, Istanbul Technical University,
Maslak 34469, Istanbul, Turkey
Mehmet Atlar: School of Marine Science and Technology, Newcastle University, Newcastle upon Tyne, NE2 1PT, United Kingdom

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