Frequency Response Tuning for a Two-Body Heaving Wave Energy Converter

摘要

This study investigates frequency response tuning for a two-body heaving wave energy converter. The wave energy converter presented is a scale model "spar-float" configuration to be tested at the National Research Council Institute for Ocean Technology, St. Johns, Newfoundland. The purpose of these tests is to validate a novel tuning mechanism which affords active adjustment of the spar natural frequency. In this work, a systematic optimization procedure is used to demonstrate the utility of this tuning mechanism. The spar geometry is parameterized so that the reference depth can be input to a simplified heaving dynamics model which utilizes the long-wavelength approximation. Closed form solutions to the linear heaving dynamics model are used to establish objective functions. For a range of wave frequencies corresponding to the wave tank capabilities, optimal natural frequencies for the spar are computed. The results show that an ability to vary the spar's natural heaving frequency is indeed beneficial, and that significant power absorption benefits can be attained at low wave frequencies using the suggested tuning mechanism to produce these frequency adjustments.