Experimental investigation of mooring configurations for wave energy converters

Paredes, Guilherme Moura; Palm, Johannes; Eskilsson, Claes; Bergdahl, Lars; Taveira-Pinto, Francisco

doi:10.1016/j.ijome.2016.04.009

Cited by 43 publications

(20 citation statements)

References 6 publications

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“…Here we analyze the influence that deviations in anchor placement have on the dynamics of a moored cylindrical buoy. The case study is based on physical model experiments of a vertical cylinder moored with spread mooring system composed of three catenaries, Figure 9 (see [46] for a close description of the physical experiments). This case has been investigated numerically by coupled mooring analysis using CFD [25] and using linear potential theory [33].…”

Section: Moored Cylindermentioning

confidence: 99%

Uncertainty Quantification in Mooring Cable Dynamics Using Polynomial Chaos Expansions

Paredes

Eskilsson

Engsig-Karup

2020

JMSE

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Mooring systems exhibit high failure rates. This is especially problematic for offshore renewable energy systems, like wave and floating wind, where the mooring system can be an active component and the redundancy in the design must be kept low. Here we investigate how uncertainty in input parameters propagates through the mooring system and affects the design and dynamic response of mooring and floaters. The method used is a nonintrusive surrogate based uncertainty quantification (UQ) approach based on generalized Polynomial Chaos (gPC). We investigate the importance of the added mass, tangential drag, and normal drag coefficient of a catenary mooring cable on the peak tension in the cable. It is found that the normal drag coefficient has the greatest influence. However, the uncertainty in the coefficients plays a minor role for snap loads. Using the same methodology we analyze how deviations in anchor placement impact the dynamics of a floating axi-symmetric point-absorber. It is shown that heave and pitch are largely unaffected but surge and cable tension can be significantly altered. Our results are important towards streamlining the analysis and design of floating structures. Improving the analysis to take into account uncertainties is especially relevant for offshore renewable energy systems where the mooring system is a considerable portion of the investment.

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Section: Moored Cylindermentioning

confidence: 99%

Uncertainty Quantification in Mooring Cable Dynamics Using Polynomial Chaos Expansions

Paredes

Eskilsson

Engsig-Karup

2020

JMSE

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“…Experiments of mooring forces on wave energy converters were conducted in the wave basin of the Faculty of Engineering of the University of Porto [11], Figure 6. A truncated cylinder in regular waves is moored with a three-cable spread catenary system (see Figure 6 for the cable data and [6] for the properties of the buoy).…”

Section: Moored Cylinder Test Case: Validation With Moodymentioning

confidence: 99%

Coupled BEM/hp-FEM Modelling of Moored Floaters

Paredes

Eskilsson

Palm

et al. 2018

Lecture Notes in Civil Engineering

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A coupling between a dynamic mooring solver based on highorder finite element techniques (MooDy) and a radiation-diffraction based hydrodynamic solver (WEC-Sim) is presented. The high-order scheme gives fast convergence resulting in high-resolution simulations at a lower computational cost. The model is compared against a lumped mass mooring code (MoorDyn) that has an existing coupling to WEC-Sim. The two models are compared for a standard test case and the results are similar, giving confidence in the new WEC-Sim-MooDy coupling. Finally, the coupled model is validated using experimental data of a spread moored cylinder with good agreement.

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“…The intention is to compare the coupled and the decoupled simulation procedures and discuss their suitability in the initial fatigue design assessment of WEC mooring lines before the detailed design is carried out. It is well-known that both prototype and full-scale field measurements provide important input data and allow models to be validated, but these measurements are too scarce and costly to present a standalone alternative at the time of writing (Harnois et al, 2015;Johanning et al, 2007;Paredes, et al 2015). Hence, numerical simulation procedures have an important task to accomplish especially in the initial design phase, i.e.…”

Section: Mooring Fatigue and Objective Of The Studymentioning

confidence: 99%

A comparison of coupled and de-coupled simulation procedures for the fatigue analysis of wave energy converter mooring lines

et al. 2016

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Newcastle University ePrints -eprint.ncl.ac.uk Yang S, Ringsberg JW, Johnson E, Hu ZQ. A comparison of coupled and decoupled simulation procedures for the fatigue analysis of wave energy converter mooring lines. Ocean Engineering 2016, 117, 332-345. AbstractMooring systems for floating wave energy converters (WECs) must be designed to survive the cyclical loads and motions to which they are subjected as a result of the wave load-WEC interaction and the motions of the WEC in the random elevation of the sea surface. The current study compares simulation procedures for the fatigue analysis of WEC moorings. The objective is to suggest a simulation procedure suitable for an extensive study of the behaviour of WEC systems and thus for the fatigue analysis of mooring lines. A cylindrical, floating WEC with four spread mooring lines is chosen as case study. The dynamics of the WEC system are simulated and analysed using both coupled and de-coupled models in the timedomain. Four types of simulation procedures are compared using commercial software, DNV DeepC, and an in-house solver, MooDy. A systematic fatigue response analysis based on variations of the numerical and physical parameters is conducted. The results are compared with respect to the fatigue damage calculated using the stress-based approach and the rainflow counting method. The simulation procedure using a coupled model is suggested as the preferred numerical method for capturing the interaction between the components of WEC system, which is proven to be crucial for the fatigue damage evaluation of mooring lines.

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Experimental investigation of mooring configurations for wave energy converters

Cited by 43 publications

References 6 publications

Uncertainty Quantification in Mooring Cable Dynamics Using Polynomial Chaos Expansions

Uncertainty Quantification in Mooring Cable Dynamics Using Polynomial Chaos Expansions

Coupled BEM/hp-FEM Modelling of Moored Floaters

A comparison of coupled and de-coupled simulation procedures for the fatigue analysis of wave energy converter mooring lines

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