Parametric experimental investigation of a floating pneumatic wave energy converter with forward and backward bent ducts

This study experimentally investigates the wave energy conversion and wave attenuation performance of a floating pneumatic wave energy converter with forward and backward bent ducts. Physical model experiments at a 1:20 scale were conducted in a wave flume to examine the effects of three key geometric parameters—orifice ratio, draft depth, and the relative height difference between the forward and backward bent-duct bottoms. Results show that the front orifice ratio governs energy conversion at short wave periods, whereas the rear orifice ratio dominates at medium-to-long periods. A favorable balance is identified with front and rear orifice ratios of 2% and 1%, yielding a broad efficient bandwidth and a low transmission coefficient of 0.57 at a prototype period of 8.2 s. Shallower draft benefits short-wave conversion, while deeper draft improves long-wave attenuation. A reduced relative height difference between the bent-duct bottoms notably enhances short- and medium-period conversion efficiency without compromising long-period performance. These findings provide quantitative design guidance for the development of floating pneumatic wave energy converters with forward and backward bent ducts.