Performance of a Tethered Point Wave-Energy Absorber in Regular and Irregular Waves

Handle URI:
http://hdl.handle.net/10754/599164
Title:
Performance of a Tethered Point Wave-Energy Absorber in Regular and Irregular Waves
Authors:
Bachynski, Erin E.; Young, Yin Lu; Yeung, Ronald W.
Abstract:
The importance of the mooring system on the dynamic response of a point-absorber type ocean-wave energy converter (WEC) is investigated using a frequency-domain approach. In order to ensure the safety of WECs, careful consideration of the response and resonance frequencies in all motions must be evaluated, including the effects of the mooring system. In this study, a WEC floater with a closed, flat bottom is modeled as a rigid vertical cylinder tethered by elastic mooring lines. The WEC hydrodynamic added mass and damping are obtained using established potential-flow methods, with additional damping provided by the energy-extraction system. The results show that the response of the WEC, and the corresponding power takeoff, varies with the diameter-to-draft (D=T) ratio, mooring system stiffness, and mass distribution. For a given wave climate in Northern California, near San Francisco, the heave energy extraction is found to be best for a shallow WEC with a soft mooring system, compared to other systems that were examined. This result assumes a physical limit (cap) on the motion which is related to the significant wave height to draft ratio. Shallow draft designs, however, may experience excessive pitch motions and relatively larger viscous damping. In order to mitigate the pitch response, the pitch radius of gyration should be small and the center of mass should be low. Copyright © 2010 by ASME.
Citation:
Bachynski EE, Young YL, Yeung RW (2010) Performance of a Tethered Point Wave-Energy Absorber in Regular and Irregular Waves. ASME 2010 7th International Symposium on Fluid-Structure Interactions, Flow-Sound Interactions, and Flow-Induced Vibration and Noise: Volume 3, Parts A and B. Available: http://dx.doi.org/10.1115/fedsm-icnmm2010-30545.
Publisher:
ASME International
Journal:
ASME 2010 7th International Symposium on Fluid-Structure Interactions, Flow-Sound Interactions, and Flow-Induced Vibration and Noise: Volume 3, Parts A and B
KAUST Grant Number:
KAUST-25478-EE08K1
Issue Date:
2010
DOI:
10.1115/fedsm-icnmm2010-30545
Type:
Conference Paper
Sponsors:
The authors gratefully acknowledge the funding provided byKing Abdullah University of Science and Technology (KAUST)to UC Berkeley, under AEA Award # KAUST-25478-EE08K1.The first author would also like to acknowledge the funding providedby the University of Michigan College of Engineering J.Reid and Polly Anderson Fellowship and a SNAME William M.Kennedy Scholarship.
Appears in Collections:
Publications Acknowledging KAUST Support

Full metadata record

DC FieldValue Language
dc.contributor.authorBachynski, Erin E.en
dc.contributor.authorYoung, Yin Luen
dc.contributor.authorYeung, Ronald W.en
dc.date.accessioned2016-02-25T13:54:05Zen
dc.date.available2016-02-25T13:54:05Zen
dc.date.issued2010en
dc.identifier.citationBachynski EE, Young YL, Yeung RW (2010) Performance of a Tethered Point Wave-Energy Absorber in Regular and Irregular Waves. ASME 2010 7th International Symposium on Fluid-Structure Interactions, Flow-Sound Interactions, and Flow-Induced Vibration and Noise: Volume 3, Parts A and B. Available: http://dx.doi.org/10.1115/fedsm-icnmm2010-30545.en
dc.identifier.doi10.1115/fedsm-icnmm2010-30545en
dc.identifier.urihttp://hdl.handle.net/10754/599164en
dc.description.abstractThe importance of the mooring system on the dynamic response of a point-absorber type ocean-wave energy converter (WEC) is investigated using a frequency-domain approach. In order to ensure the safety of WECs, careful consideration of the response and resonance frequencies in all motions must be evaluated, including the effects of the mooring system. In this study, a WEC floater with a closed, flat bottom is modeled as a rigid vertical cylinder tethered by elastic mooring lines. The WEC hydrodynamic added mass and damping are obtained using established potential-flow methods, with additional damping provided by the energy-extraction system. The results show that the response of the WEC, and the corresponding power takeoff, varies with the diameter-to-draft (D=T) ratio, mooring system stiffness, and mass distribution. For a given wave climate in Northern California, near San Francisco, the heave energy extraction is found to be best for a shallow WEC with a soft mooring system, compared to other systems that were examined. This result assumes a physical limit (cap) on the motion which is related to the significant wave height to draft ratio. Shallow draft designs, however, may experience excessive pitch motions and relatively larger viscous damping. In order to mitigate the pitch response, the pitch radius of gyration should be small and the center of mass should be low. Copyright © 2010 by ASME.en
dc.description.sponsorshipThe authors gratefully acknowledge the funding provided byKing Abdullah University of Science and Technology (KAUST)to UC Berkeley, under AEA Award # KAUST-25478-EE08K1.The first author would also like to acknowledge the funding providedby the University of Michigan College of Engineering J.Reid and Polly Anderson Fellowship and a SNAME William M.Kennedy Scholarship.en
dc.publisherASME Internationalen
dc.titlePerformance of a Tethered Point Wave-Energy Absorber in Regular and Irregular Wavesen
dc.typeConference Paperen
dc.identifier.journalASME 2010 7th International Symposium on Fluid-Structure Interactions, Flow-Sound Interactions, and Flow-Induced Vibration and Noise: Volume 3, Parts A and Ben
dc.contributor.institutionUniversity Michigan Ann Arbor, Ann Arbor, United Statesen
dc.contributor.institutionUC Berkeley, Berkeley, United Statesen
kaust.grant.numberKAUST-25478-EE08K1en
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