Hydrodynamics performance of backward bend duct buoy (BBDB) inregular and irregular waveconditions

There are several projects conducted worldwide on various wave energy converter designs especially floating oscillating water column (FOWC) type. The most investigated FOWC device is currently the backward bent duct buoy (BBDB) concept focusing on regular and high-heave wave conditions, which is different to the low-heave wave ocean conditions in Malaysia. It was found that very few studies were done for BBDB under irregular wave conditions, which represents the real ocean condition. Therefore, this study presents the comparison of the performance and behaviour of BBDB under regular and irregular for low-heave wave conditions. Parameters such as water level inside column, air pressure and the air flow rate inside the device as well as the primary conversion efficiency were measured and calculated. The BBDB model with inclined 45 bottom corner was designed and tested at Natural Hydraulic Research Institute of Malaysia (NAHRIM) using the 3D wave tank in both regular and irregular waves conditions. The result showed that the highest efficiency can be extracted in low heave wave condition ranging from λ/L = 4.2 to λ/L = 4.8. Higher primary conversion efficiencies were achieved in regular compared to irregular wave conditions.