Performance characteristics of a tightly moored piston-like wave energy converter under first- and second-order wave loads

Mavrakos, SA; Katsaounis, GM; Chatjigeorgiou, LK

dc.contributor.author	Mavrakos, SA	en
dc.contributor.author	Katsaounis, GM	en
dc.contributor.author	Chatjigeorgiou, LK	en
dc.date.accessioned	2014-03-01T02:51:46Z
dc.date.available	2014-03-01T02:51:46Z
dc.date.issued	2008	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/35644
dc.relation.uri	http://www.scopus.com/inward/record.url?eid=2-s2.0-77957985549&partnerID=40&md5=16926553de877a3677f5967a53903cb6	en
dc.subject.other	Analysis method	en
dc.subject.other	Axisymmetric	en
dc.subject.other	Concentric cylinders	en
dc.subject.other	Coupling terms	en
dc.subject.other	Different modes	en
dc.subject.other	Diffraction radiation	en
dc.subject.other	First-order	en
dc.subject.other	Floating devices	en
dc.subject.other	Fluid regions	en
dc.subject.other	Forcing terms	en
dc.subject.other	Frequency domains	en
dc.subject.other	Hydraulic cylinders	en
dc.subject.other	Hydraulic system	en
dc.subject.other	Hydrodynamic characteristics	en
dc.subject.other	Hydrodynamic parameters	en
dc.subject.other	Inner cylinder	en
dc.subject.other	Memory effects	en
dc.subject.other	Modes of motion	en
dc.subject.other	Moonpools	en
dc.subject.other	Performance characteristics	en
dc.subject.other	Pressurized oil	en
dc.subject.other	Radiation problems	en
dc.subject.other	Second orders	en
dc.subject.other	Semi-analytical	en
dc.subject.other	Semi-analytical methods	en
dc.subject.other	Velocity potentials	en
dc.subject.other	Wave energy converters	en
dc.subject.other	Wave force	en
dc.subject.other	Wave load	en
dc.subject.other	Wave potentials	en
dc.subject.other	Arctic engineering	en
dc.subject.other	Cylinders (shapes)	en
dc.subject.other	Diffraction	en
dc.subject.other	Fluid dynamics	en
dc.subject.other	Frequency domain analysis	en
dc.subject.other	Hydraulic equipment	en
dc.subject.other	Hydraulics	en
dc.subject.other	Hydrodynamics	en
dc.subject.other	Leakage (fluid)	en
dc.subject.other	Mechanics	en
dc.subject.other	Renewable energy resources	en
dc.subject.other	Sailing vessels	en
dc.subject.other	Structural loads	en
dc.subject.other	Technical presentations	en
dc.subject.other	Wave power	en
dc.subject.other	Wave energy conversion	en
dc.title	Performance characteristics of a tightly moored piston-like wave energy converter under first- and second-order wave loads	en
heal.type	conferenceItem	en
heal.publicationDate	2008	en
heal.abstract	The paper deals with the presentation of a model to predict performance characteristics of a tightly moored piston-like wave energy converter which is allowed to move in heave, pitch and sway modes of motion. The WEC's piston-like arrangement consists of two floating concentric cylinders, the geometry of which allow the existence of a cylindrical moonpool between the external cylinder, the 'torus' and the inner cylinder, the 'piston'. The first-order hydrodynamic characteristics of the floating device, i.e. exciting wave forces and hydrodynamic parameters, are evaluated using a linearized diffraction-radiation semi-analytical method of analysis that is suited for the type of bodies under consideration. According to the analysis method used, matched axisymmetric eigenfiinction expansions of the velocity potentials in properly defined fluid regions around the body are introduced to solve the respective diffraction and radiation problems and to calculate the floats' hydrodynamic characteristics in the frequency domain (Mavrakos et al. 2004, 2005). Based on these characteristics, the retardation forcing terms are calculated, which account for the memory effects of the motion. In this procedure, the coupling terms between the different modes of motion are properly formulated and taken into account (Cummins, 1962; Faltinsen, 1990).The floating WEC is connected to an underwater hydraulic cylinder that feeds a hydraulic system with pressurized oil. The performance of the system under the combined excitation of both first- and second order wave loads is here analyzed. To this end, the diffraction forces originated from the second order wave potentials are computed using a semi- analytical formulation which, by extension of the associated first-order solution, is based on matched axisymmetric eieenfunction expansions. Copyright © 2008 by ASME.	en
heal.journalName	Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE	en
dc.identifier.volume	6	en
dc.identifier.spage	783	en
dc.identifier.epage	792	en