Extraction of Wave Energy Using the Coupled Heaving Motion of a Circular Cylinder and Linear Electric Generator

doi:2011.25.6.9

J. Ocean Eng. Technol. > Volume 25(6); 2011 > Article

J. Ocean Eng. Technol. 2011;25(6):9-16.
DOI: https://doi.org/10.5574/KSOE.2011.25.6.009

Cho Il-Hyoung,Kweon Hyuck-Min

Department of Ocean System Engineering Jeju National University,Department of Civil Engineering Kyongju University

원기둥과 선형발전기의 연성 수직운동을 이용한 파 에너지 추출

조일형,권혁민

제주대학교 해양시스템공학과,경주대학교 토목공학과

Keywords: Heave motion, Linear electric generator, Power absorbtion, Matched eigenfunction expansion method, Double resonance, Circular cylinder

핵심용어: 수직운동, 선형발전기, 에너지 흡수, 고유함수전개법, 이중 공진, 원기둥

Abstract

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.