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- Numerical and experimental analysis of a hybrid wind-wave offshore floating platform’s hullPublication . Hallak, Thiago S.; Gaspar, José F.; Kamarlouei, Mojtaba; Calvário, Miguel; Gonçalves Cavaco Mendes, Mário José; Thiebaut, Florent; Guedes Soares, CarlosThis paper presents a study regarding a novel hybrid concept for both wind and wave energy offshore. The concept resembles a semi-submersible wind platform with a larger number of columns. Wave Energy Devices such as point absorbers are to be displayed around the unit, capturing wave energy while heaving and also enhancing the stability of the platform. In this paper, a first numerical study of the platform’s hull, without Wave Energy Converters, is carried out. Experiments in wave basin regarding the same unit have been conducted and the results are presented and compared to the numerical ones. Both stability and seakeeping performances are assessed and compared.
- On the experimental study of a concentric wave energy array adapted to an offshore floating platformPublication . Kamarlouei, Mojtaba; Gaspar, José F.; Calvário, Miguel; Hallak, Thiago S.; Mendes, Mário J. G. C.; Thiebaut, Florent; Guedes Soares, CarlosExperimental results of the dynamics of a small scale concentric wave energy converter array adapted to a floating offshore platform are presented. A small scale prototype is tested without and with twelve conical heaving point absorbers. The free decay and regular wave tests are carried out in an ocean basin to understand the hydrodynamic interactions between various elements of the floating offshore platform and wave energy converter array. Meanwhile, the heave motions of the buoys are observed in regular waves with and without dampers for the initial estimation of power take-off damping as a pitch control module. The results show the improvements in heave, pitch, and roll performance of the platform due to the interaction between the buoys and platform.
- Experimental analysis of wave energy converters concentrically attached on a floating offshore platformPublication . Kamarlouei, M.; Gaspar, José; Calvário, Miguel; Hallak, T. S.; Mendes, Mário J. G. C.; Thiebaut, F.; Soares, Carlos GuedesThis paper presents an initial experimental study of wave energy converters concentrically arranged and attached on a floating offshore platform model. The 1:27 scale model, has been designed, built and tested, in two main situations, without and with twelve cone shape wave energy converters. To simulate the power take-off system in each wave energy converter, rotational friction dampers have been installed on the joints of the floaters arms to the platform deck. The experimental results show that the interaction between buoys and platform have a positive effect on the platform heave and pitch motions. However, the reduction in heave and pitch motions of the platform, after installing the wave energy converter array, depends on the damping of the equivalent power take-off system. Thus, the effect of dampers in the motion of buoys is presented to allow an initial understanding of the required damping range of the power take-off system and related control strategies.
- Experimental study of wave energy converter arrays adapted to a semi-submersible wind platformPublication . Kamarlouei, M.; Gaspar, José; Calvário, Miguel; Hallak, T. S.; Mendes, Mário J. G. C.; Thiebaut, F.; Guedes Soares, CarlosThe design of an offshore wind turbine floating platform seeks to minimize platform pitching motions that otherwise generate large accelerations and loads on the turbine, nacelle and blades, and decrease their lifetime. This objective is harder to achieve as the upscaling to more powerful wind turbines amplify the effects of pitching motions since the wind turbines’ height and mass are higher. Thus, innovative solutions to control the pitching motions should be developed. This study presents a solution based on a concentric array of wave energy converters which was originally designed to be attached on a floating platform to generate wave energy. Meanwhile, it was found that the concept may provide bigger restoring moments for platforms, amplified by its lever type arms, which are useful to control the pitching motions. Thus, a wind thrust simulator is adapted to the original experimental model and tests performed to understand the advantage of using these converters in the control of the pitching motions of a wind turbine platform. The experimental results indicate that platform motions are controllable by the wave energy converters however must be optimized to achieve better performance. These results also provide some design knowledge to test the concept at bigger rated power wind turbines.