Modelling, simulation and testing of a submerged oscillating water column

Abstract

This paper presents the development of a time-domain simulation model, with experimental verification, for a submerged oscillating water column (OWC). The Stellenbosch Wave Energy Converter (SWEC) makes use of series of these submerged chambers in order to create a rectified flow through a single turbine. The main objective of this research was to produce a verified and validated simulation model for a single chamber of the SWEC. The mathematical model was derived from first principles and then coded in Simulink. The simulation results were verified using measurements from a scale model in a wave tank test. The model provides a better understanding of the hydrodynamics and thermodynamics associated with the submerged chamber. The submerged chamber achieved a peak conversion efficiency of 22%. The device achieved a conversion efficiency of 13% at the expected operating conditions when orientated at 45° with regards to the incident waves. The simulation model predicted the transmissibility of the device with errors which ranged from 0% to 20% with the majority of the errors being less than 5%. The model predicted the conversion efficiency of the device with errors which ranged from 0% to 43% with the majority of the errors being less than 15%.