An Experimental Study on Primary Efficiency of a Wave Energy Converter "Backward Bent Duct Buoy" in regular wave conditions

Imai, Yasutaka; Nagata, Shinji; Toyota, Kazutaka; Murakami, Tengen

doi:10.2534/jjasnaoe.19.79

Cited by 9 publications

(6 citation statements)

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“…(12), (14), or (15), and this will become evident when we look at the effect of the piston lengths later in the research. However, due to the interaction between the float body and the imaginary pistons, in the dynamic system, the mass and added mass must be considered together, as shown in Table II.…”

Section: Comments On the Piston Representationmentioning

confidence: 99%

“…Toyota et al 14 have shown that both the size of the air chamber and the length of the horizontal duct length of a Backward Bent Duct Buoy (BBDB) device have significant effects on the primary power conversion of the OWC wave energy converters. Imai et al 15 have studied the influence of the horizontal duct length to the wave energy capture capacity in a BBDB device and shown that a longer horizontal duct has increased the maximum IWS response to a longer resonance period. As a result of this, a longer horizontal duct may be desirable for tuning the BBDB to the wave states of longer wave periods.…”

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confidence: 99%

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Assessment of primary energy conversions of oscillating water columns. I. Hydrodynamic analysis

Sheng

Alcorn

Lewis

2014

Journal of Renewable and Sustainable Energy

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This is an investigation on the development of a numerical assessment method for the hydrodynamic performance of an oscillating water column (OWC) wave energy converter. In the research work, a systematic study has been carried out on how the hydrodynamic problem can be solved and represented reliably, focusing on the phenomena of the interactions of the wave-structure and the wave-internal water surface. These phenomena are extensively examined numerically to show how the hydrodynamic parameters can be reliably obtained and used for the OWC performance assessment. In studying the dynamic system, a two-body system is used for the OWC wave energy converter. The first body is the device itself, and the second body is an imaginary “piston,” which replaces part of the water at the internal water surface in the water column. One advantage of the two-body system for an OWC wave energy converter is its physical representations, and therefore, the relevant mathematical expressions and the numerical simulation can be straightforward. That is, the main hydrodynamic parameters can be assessed using the boundary element method of the potential flow in frequency domain, and the relevant parameters are transformed directly from frequency domain to time domain for the two-body system. However, as it is shown in the research, an appropriate representation of the “imaginary” piston is very important, especially when the relevant parameters have to be transformed from frequency-domain to time domain for a further analysis. The examples given in the research have shown that the correct parameters transformed from frequency domain to time domain can be a vital factor for a successful numerical simulation

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Section: Comments On the Piston Representationmentioning

confidence: 99%

mentioning

confidence: 99%

Assessment of primary energy conversions of oscillating water columns. I. Hydrodynamic analysis

Sheng

Alcorn

Lewis

2014

Journal of Renewable and Sustainable Energy

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“…Relevant wave energy conversion efficiencies for a number of OWC devices evaluated in wave tanks/flumes have been included in Table 2 , showing significant variations from one another. In this regard, 55 claims that a generic OWC has a relatively poor wave energy conversion efficiency of 7.5%, while in studies 56 the efficiency was found to be 35%. Wells turbine is limited to avoid stalling behaviour.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

A regressive machine-learning approach to the non-linear complex FAST model for hybrid floating offshore wind turbines with integrated oscillating water columns

Ahmad

M’zoughi

Aboutalebi

et al. 2023

Sci Rep

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Offshore wind energy is getting increasing attention as a clean alternative to the currently scarce fossil fuels mainly used in Europe’s electricity supply. The further development and implementation of this kind of technology will help fighting global warming, allowing a more sustainable and decarbonized power generation. In this sense, the integration of Floating Offshore Wind Turbines (FOWTs) with Oscillating Water Columns (OWCs) devices arise as a promising solution for hybrid renewable energy production. In these systems, OWC modules are employed not only for wave energy generation but also for FOWTs stabilization and cost-efficiency. Nevertheless, analyzing and understanding the aero-hydro-servo-elastic floating structure control performance composes an intricate and challenging task. Even more, given the dynamical complexity increase that involves the incorporation of OWCs within the FOWT platform. In this regard, although some time and frequency domain models have been developed, they are complex, computationally inefficient and not suitable for neither real-time nor feedback control. In this context, this work presents a novel control-oriented regressive model for hybrid FOWT-OWCs platforms. The main objective is to take advantage of the predictive and forecasting capabilities of the deep-layered artificial neural networks (ANNs), jointly with their computational simplicity, to develop a feasible control-oriented and lightweight model compared to the aforementioned complex dynamical models. In order to achieve this objective, a deep-layered ANN model has been designed and trained to match the hybrid platform’s structural performance. Then, the obtained scheme has been benchmarked against standard Multisurf-Wamit-FAST 5MW FOWT output data for different challenging scenarios in order to validate the model. The results demonstrate the adequate performance and accuracy of the proposed ANN control-oriented model, providing a great alternative for complex non-linear models traditionally used and allowing the implementation of advanced control schemes in a computationally convenient, straightforward, and easy way.

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“…1B shows the hydrodynamic counterpart (note only the wetted surface must be modeled for the potential flow BEM solver). The width of the device is 27 m. The majority of the device dimensions were selected based upon the conclusions of the following papers Imai et al (2011), Suzuki et al (2011), and Hong et al (2004. The ballast is assumed to be seawater and is added to the buoyancy chambers as shown in Fig.…”

Section: Bbdbmentioning

confidence: 99%

An improved understanding of the natural resonances of moonpools contained within floating rigid-bodies: Theory and application to oscillating water column devices

Bull

2015

Ocean Engineering

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a b s t r a c tThe fundamental interactions between waves, a floating rigid-body, and a moonpool that is selectively open to atmosphere or enclosed to purposefully induce pressure fluctuations are investigated. The moonpool hydrodynamic characteristics and the hydrodynamic coupling to the rigid-body are derived implicitly through reciprocity relations on an array of field points. By modeling the free surface of the moonpool in this manner, an explicit hydrodynamic coupling term is included in the equations of motion. This coupling results in the migration of the moonpool's natural resonance frequency from the piston frequency to a new frequency when enclosed in a floating rigid-body. Two geometries that highlight distinct aspects of marine vessels and oscillating water column (OWC) renewable energy devices are analyzed to reveal the coupled natural resonance migration. The power performance of these two OWCs in regular waves is also investigated. The air chamber is enclosed and a three-dimensional, linear, frequency domain performance model that links the rigid-body to the moonpool through a linear resistive control strategy is detailed. An analytic expression for the optimal linear resistive control values in regular waves is presented.

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An Experimental Study on Primary Efficiency of a Wave Energy Converter "Backward Bent Duct Buoy" in regular wave conditions

Cited by 9 publications

References 0 publications

Assessment of primary energy conversions of oscillating water columns. I. Hydrodynamic analysis

Assessment of primary energy conversions of oscillating water columns. I. Hydrodynamic analysis

A regressive machine-learning approach to the non-linear complex FAST model for hybrid floating offshore wind turbines with integrated oscillating water columns

An improved understanding of the natural resonances of moonpools contained within floating rigid-bodies: Theory and application to oscillating water column devices

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