Hydrodynamics and Load Shedding Behavior of a Variable-Geometry Oscillating Surge Wave Energy Converter (OSWEC)

Journal Article · Fri Jun 10 04:00:00 EDT 2022 · Renewable Energy

DOI:https://doi.org/10.1016/j.renene.2022.05.169· OSTI ID:1874945

Choiniere, Michael; Davis, Jacob; Nguyen, Nhu; Tom, Nathan; Fowler, Matthew; Thiagarajan, Krish

In order to improve their long-term viability, wave energy converters (WECs) need to be able to shed loads when a threshold wave condition is exceeded. As shown by Tom et al. (2016) [1], provision of adjustable flaps within the body of an oscillating surge wave energy converter (OSWEC) allows wave energy to pass through the device. A control system may then be able to open and close the flaps when waves approaching the device exceed preset thresholds. The variable-geometry OSWEC (VG-OSWEC) concept studied in this paper is a bottom-hinged, rectangular wave paddle with five flaps of elliptical cross-section embedded into the face of the paddle. System ID tests were conducted on this VG-OSWEC device at a 1:14 scale in a wave basin. Free decay tests showed that the damping was distinctly nonlinear when the flaps were fully open, and the natural frequency increased by 40% when compared with the flaps in a fully closed configuration. Tests with regular wave conditions were used to develop the response amplitude operator for the rotational motion about the hinge. These response amplitude operator results when compared with numerical simulations run using WEC-Sim/WAMIT and ANSYS AQWA, show strong agreement with the flap open and closed conditions. The regular-wave condition measurements also show that the wave excitation moment about the hinge was reduced by up to 60% when the flaps were fully open. The experiments serve to demonstrate the potential of the variable geometry design to shed loads and survive harsh ocean environments.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Water Power Technologies Office (EE-4W)
• DOE Contract Number: AC36-08GO28308
• OSTI ID: 1874945
• Report Number(s): NREL/JA-5700-80543; MainId:43745; UUID:4bfce6a6-67bb-4680-82dc-37cb25ce296c; MainAdminID:64797
• Journal Information: Renewable Energy, Journal Name: Renewable Energy Vol. 194
• Country of Publication: United States
• Language: English

Related Subjects

TIDAL AND WAVE POWER
load shedding
model tests
oscillating surge wave energy converter
response amplitude operator
wave energy conversion
wave hydrodynamics