Document Type : Original Article
Authors
1 Master of Science, Sea-Based Energy Research Group, Babol Noshirvani University of Technology,
2 Professor, Sea-Based Energy Research Group, Babol Noshirvani University of Technology, Babol, Iran
3 Assistant Professor, Sea-Based Energy Research Group, Babol Noshirvani University of Technology, Babol, Iran
Abstract
The performance of tidal turbines hinges on geometric characteristics and wave-current properties. This study investigates the performance of a three-bladed, 1:6 scale horizontal axis tidal turbine (HATT), with a particular focus on the underexplored influence of flow direction—a critical factor for bi-directional tidal sites. The effects of various variables, including pitch angle, flow direction, electrical load, and wave-current interaction under different tip speed ratios, were systematically studied. Power and moment of force coefficients (Cp and Cm) alongside their TSRs were considered as the objective functions. The wave characteristics of the Khoran Strait were scaled using Froude methodology. The Cp and Cm at the optimal pitch angle range for downstream flow do not exceed a maximum increase of 6.5% compared to the no-wave modes. When the HATT operates at its optimum variables, the power coefficient increased by 35% compared to the lowest level. However, due to the generator's characteristics, the increase in power and moment of force follows a non-linear trend. The variations in Cp and Cm at different TSRs also form a parabolic pattern. A key novel contribution of this study is the comprehensive comparison of upstream versus downstream flow configurations, revealing that the turbine's power and moment of force coefficients in the upstream flow state increase by 36.1% and 18.1%, respectively, compared to the same pitch angles in the downstream flow state, due to the absence of the nacelle impeding the current. This finding provides crucial design guidance for bi-directional tidal turbine installations.
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