Abstract: This study examines the backward bent duct buoy (BBDB) as an oscillating water column (OWC) wave energy converter, and develops a BBDB-OWC device integrated with certain foils to optimize the bottom-mounted appendages. A three-dimensional computational fluid dynamics (CFD) model is constructed in the framework of STAR-CCM+ to couple wave propagation, air chamber compression, and structural response, and focus on comprehensive analysis of the effects of foil parameters－including chord length, width, and spatial positioning－on the hydrodynamic performance of this device under regular wave conditions. The simulation results indicate the foils can alter the local flow field structure and turbulence distribution, imposing a certain influence on the vorticity field around the device. However, its contribution to the overall energy conversion efficiency is limited, with the capture width ratio varying by no more than 5%. This study demonstrates the stability of the device’s hydrodynamic performance under the effect of foils, and helps further studies on parametric design and optimization of the appendage structures for wave energy converters.

Key words: backward bent duct buoy, oscillating water column wave energy converter, foil, numerical simulation, energy conversion efficiency