Numerical modelling of an array of heaving point absorbers

Sinha, Ashank; Karmakar, D.; Soares, C

doi:10.1201/b18973-54

Cited by 11 publications

(8 citation statements)

References 5 publications

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“…5(a) are indicating the localization of the tags for measuring the movements of the platform deck and the red ones for monitoring the movements of buoys. The buoy tags are named as B 11 , B 12 , B 21 , B 22 and their associated tags on the deck as C 11 , C 12 , C 21 , and C 22 , respectively from port to starboard. The T-section and mentioned camera tags for monitoring the movements of the platform in 6 DoF are presented in Fig.…”

Section: Methodsmentioning

confidence: 99%

“…In addition, studies were developed on the concentric WEC arrays however dedicated to point floater WECs made of different shapes [22,23]. The simulations indicate that a cone-cylinder floater is a better wave absorber than the hemisphere-cylinder and hemisphere floaters, because it has better hydrodynamic properties [22]. Meanwhile, the average power absorbed by coneshape floater does not contribute to a significant improve when compared to the other floater shapes.…”

Section: Concentric Wec Concept and Modelmentioning

confidence: 99%

“…Meanwhile, the average power absorbed by coneshape floater does not contribute to a significant improve when compared to the other floater shapes. The use of these cone shaped floaters in circular arrays was also studied for a layout of 12 WECs with different diameters, and a better total extracted power was found for the larger radius of array, despite of the increasing costs in the construction and maintenance of a bigger structure [22]. The absorbed power is uniformly distributed in the circular arrangement while it is unevenly distributed in the linear and grid type arrays, where the front floaters extract more power than the rear ones, and thus, the circular array provides a better power quality (smoothness).…”

Section: Concentric Wec Concept and Modelmentioning

confidence: 99%

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Experimental analysis of wave energy converters concentrically attached on a floating offshore platform

et al. 2020

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This 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 takeoff 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 takeoff 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 takeoff system and related control strategies.

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Section: Methodsmentioning

confidence: 99%

Section: Concentric Wec Concept and Modelmentioning

confidence: 99%

Section: Concentric Wec Concept and Modelmentioning

confidence: 99%

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Experimental analysis of wave energy converters concentrically attached on a floating offshore platform

et al. 2020

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“…6) [20] with an apex angle of 90 and a diameter of 5 m extended by a cylindrical part of 0.5 m (3 m total equilibrium draft) was used in the analysis. This floater was attached to a structure borrowed from Ref.…”

Section: Hydrodynamics Of the Point Floater Wecmentioning

confidence: 99%

Speed control of oil-hydraulic power take-off system for oscillating body type wave energy converters

et al. 2016

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a b s t r a c tThe variable displacement oil-hydraulic pumps for the Power Take-Off (PTO) of wave energy converters must work above 80% of maximum displacement in order to have an overall efficiency of approximately 94.5%. This is achieved by controlling their rotational speed when the oil-hydraulic power fluctuates in time. Three speed control strategies have been presented, the first fixing the maximum possible speed in each sea state, the second by slowly varying the pump speed between speed peak values and average ones, and the third by working with highly variable speed reference values. The worst pump efficiency is achieved with the first strategy while the best one with the third strategy. However, the first has less impact than the third one in the pump lifecycle. On the other hand, the second strategy is used to make a trade-off between pump efficiency and lifecycle. However, this paper presents a fourth speed control strategy, which is a hybrid of the second and third strategies. So, the objectives of this paper were to know if these strategies are implementable in a test rig and also on a new PTO concept and determining what modifications should be introduced in these PTO strategies and hardware. This paper also contributes with the application of new methodologies in this field of research for the modelling of pump efficiency and pressure control, such as Neuro-Fuzzy modelling and Fuzzy Logic control systems.

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“…Moreover, the floaters in the inner circle are placed 30° from the corresponding floaters on the outer circle. The results of these concentric arrays are compared with linear and grid arrangements as in Sinha et al (2015) and Backer et al (2009), respectively. From the previous study (Sinha et al, 2015), a cone-cylinder floater shape, with an apex angle of 90° and a diameter of 5 m extended by a cylindrical part of 0.5 m, is chosen to be used in all the concentric arrays.…”

Section: Concentric Arraysmentioning

confidence: 99%

Hydrodynamic performance of concentric arrays of point absorbers

Sinha

Karmakar

Soares

2016

The International Journal of Ocean and Climate Systems

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The behaviour of arrays of 12 heaving point absorbers in concentric arrangements is numerically assessed in a frequency domain model. The floaters are attached to a central cylindrical bottom-mounted structure. Each point absorber is restricted to the heave mode and is assumed to have its own linear power take-off system consisting of an external damping coefficient enabling power extraction and a supplementary mass coefficient tuning the point absorber to the incoming waves. The external damping and supplementary mass coefficients are optimized to maximize the power absorption by each floater in the array, with a restriction on the total control force that can be applied on the floaters. Various concentric arrangements with different radii and number of concentric circles are analysed to determine the most efficient among them. Moreover, the influence of the presence of a central bottom-mounted pillar and the effect of change in its dimension and shape on the power absorption are also studied.

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Numerical modelling of an array of heaving point absorbers

Cited by 11 publications

References 5 publications

Experimental analysis of wave energy converters concentrically attached on a floating offshore platform

Experimental analysis of wave energy converters concentrically attached on a floating offshore platform

Speed control of oil-hydraulic power take-off system for oscillating body type wave energy converters

Hydrodynamic performance of concentric arrays of point absorbers

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