Performance enhancement for a dual-chamber OWC conceived from side wall effects in narrow flumes

Abstract

Performance enhancement is always the focus for the exploration in oscillating water column (OWC) wave energy converter devices. In the present study, the hydrodynamic characteristics of a dual-chamber OWC system composed of two 3D circular sub-units is examined under the framework of OpenFOAM. The model-scale simulations are firstly carried out in a wave flume with different widths under the excitation of regular waves. Then, conceived from the side wall effects in narrow flumes, a pair of harbor walls parallel to the wave propagation direction is introduced; by tuning its deployed location and geometric dimension, the enhancement of wave power extraction can be expected. The results indicate that significant estimation errors in the capture width ratio may occur when the incident wave length is nearly equal to the flume width or the resonant frequency of water column is close to the wave frequency in a narrow flume. In addition, the integrated system consisting of OWC and harbor walls shows that the distance between above two structures can be tuned to a threshold value to maximize the capture width ratio by strengthening the fluids and structures interaction. The medium submerged depth of harbor walls may be an alternative when the trade-off between performance enhancement and economic costs has to be considered during practical construction. Moreover, a well agreement between the model-scale and prototype-scale results proves that the performance enhancement can be scalable to large scales by integrating OWC device with harbor walls.