Physical model study on the performance of a pneumatic wave energy converter

• Conduct a physical model study on pneumatic backward bent duct buoy wave energy converter . • Explore the effect of air chamber height on wave energy capture width ratio. • Reveal the efficiency enhancement and bandwidth expansion of bow bottom plate. • Demonstrate the performance of floating ball mooring is better than bottom mooring or Y-shaped mooring. • Find the occurrence of maximum air chamber pressure and mooring loads in large sea conditions rather than largest sea conditions. In order to provide reference data for the detailed design of the first 100 kW pneumatic backward bent duct buoy (BBDB) wave energy conversion (WEC) device ‘WaveLoong’ in China, a series of physical model tests were conducted in a wave flume. The effect of air chamber height, bow bottom plate length, mooring method and wave parameter on the distribution of operational range with high capture width ratio (CWR) were explored. Results revealed that the performance of a short air chamber is superior to that of a tall air chamber, and that the converter with bow bottom plates exhibit bimodal CWR distribution, while the converter with a floating ball mooring system exhibits trimodal CWR distribution and thus shows the widest working range among all tested cases. The influence of four representative actual waves on the mooring force of the wave energy converter with a floating ball mooring system was studied, and it was found that the maximum mooring force acting on the converter occurred under medium large wave conditions rather than the most extreme wave conditions.