Extraction of Wave Energy Using the Coupled Heaving Motion of a Circular Cylinder and Linear Electric Generator Cho, Il-Hyoung; Kweon, Hyuck-Min;
The feasibility of wave energy extraction from a heaving truncated cylinder and the corresponding response of the linear electric generator (LEG) composed of spring, magnet, and coil has been investigated in the frame of three-dimensional linear potential theory. The heaving motion of a circular cylinder is calculated by means of the matched eigenfunction expansion method. Further, the analytical results are validated by numerical results using the ANSYS AQWA commercial code. By the action of a heaving circular cylinder, the magnet suspended by a spring can slide vertically inside the heaving cylinder. The mechanical power is extracted from the magnet motion relative to the coil/stator which is attached to the cylinder. The coupled ODE of a heaving cylinder and LEG system in waves is derived to obtain the magnet motion relative to a cylinder. To maximize the relative motion of the magnet, both the buoy draft and the LEG system parameters (spring stiffness, damping) should be selected properly for generating the double resonance considering the peak frequency of the target spectrum.
Heave motion;Linear electric generator;Power absorbtion;Matched eigenfunction expansion method;Double resonance;Circular cylinder;
Design of Wave Energy Extractor with a Linear Electric Generator -Part II. Linear Generator, Journal of the Korean Society for Marine Environment & Energy, 2014, 17, 3, 174
Experimental study of wave energy extraction by a dual-buoy heaving system, International Journal of Naval Architecture and Ocean Engineering, 2016
Wave Power Extraction by Strip Array of Multiple Buoys, Journal of Ocean Engineering and Technology, 2014, 28, 5, 474
Design of Wave Energy Extractor with a Linear Electric Generator -Part I. Design of a Wave Power Buoy, Journal of the Korean Society for Marine Environment & Energy, 2014, 17, 2, 146
Budal, K. and Falnes J. (1975). "A Resonant Point Absorber of Ocean Wave Power", Nature, Vol 256, pp 478-479.
French, M.J. (1979). "A Generalized View of Resonant Energy Transfer", J. Mech. Engng. Science, Vol 21, pp 299-300.
Garrett, C.J.R (1971). "Wave Forces on a Circular Dock", J. Fluid Mech.,Vol 46, pp 129-139.
Grilli, A.R., Merrill, J., Grilli, S.T., Spaulding, M.L. and Cheung, J. (2007). "Experimental and Numerical Study of Spar Buoy-magnet/Spring Oscillators Used as Wave Energy Absorbers", Proc. 17th Intl. Conf. Offshore and Polar Eng., No 2007-JSC-569.
McIver, P. and Evans, D.V. (1984). "The Occurrence of Negative Added Mass in Free-surface Problems Involving Submerged Oscillating Bodies", J. Engrg. Mech.,Vol 18, pp 7-22.
Miles, J.W. and Gilbert, F. (1968). "Scattering of Gravity Waves by a Circular Dock", J. Fluid Mech.,Vol 34, pp 783-793.
Omholt, T. (1978). "A Wave Activated Electric Generator", Proc. "Ocean 78" Marine Technology Conference, Washington, D.C., pp 585-589.
Stallard, T., Rothschild, R., Bradshaw, A. and Aggidis G. (2005). "Comparision of Equivalent Capacity Wave Energy Schemes," Proc. World Renewable Energy Congress IX (WREC 2005).
Tung, C.C. (1979). "Hydrodynamic Forces on Submerged Vertical Circular Cylindrical Tanks Under Ground Excitation", Appl. Ocean Res.,Vol 1, pp 75-78.
Yeung, R.W. (1981). "Added Mass and Damping of a Vertical Cylinder in Finite-depth Waters", Appl. Ocean Res., Vol 3, No 3, pp 119-133.