The effects of surge motion on floating horizontal axis tidal turbines
Wave induced motions due to actual sea state conditions will impact the performance of floating horizontal axis tidal turbine systems. This paper presents the results from numerical simulations of a 3-bladed horizontal axis tidal turbine oscillating in surge motion in a moving reference frame. The optimum tip-speed ratio, λ = 4.4 and k-ω SST turbulence model were used in the present study. The Navier-Stokes equation was modified by adding an inertial term to the equation and the Dirichlet boundary condition was also modified in order to simulate in the moving reference frame. The surge oscillations were parameterised in terms of the ratio of surge amplitude to rotor radius, A*, and the ratio of oscillation frequency to the rotational frequency of the rotor, ω*. A series of tests were conducted to study the effect of each parameter on the hydrodynamic performance of the tidal turbine. The results show that stall can occur on the blade when the velocity relative to the rotor is sufficiently high. In certain cases, negative thrust and power coefficients were observed when the velocity relative to the rotor is low. The fluctuation in blade loading increases together with the amplitude and frequency of oscillation, which will contribute to the fatigue of the rotor.
Copyright (c) 2020 Mohamad Osman, Richard H. J. Willden, Christopher R. Vogel
This work is licensed under a Creative Commons Attribution 4.0 International License.
I the author/we the authors understand that I/we retain copyright over our article. I/we grant a licence to IMEJ to: publish my/our article under the terms of the Creative Commons Attribution (CC BY) License which permits use, distribution and reproduction in any medium, provided the original work is properly cited, and identify IMEJ as the original publisher.