Experimental analysis of submerged flapping foils; implications for autonomous surface vehicles (ASVs)

Autonomous surface vehicles (ASVs) have proven effective as ocean observing platforms for maritime operations. In most cases it is advantageous to operate ASVs for extensive missions in order to maximize their cost effectiveness. Such long endurance missions require ASVs to be capable of scavenging ambient energy from the surrounding ocean environment. Submerged flapping foils are currently utilized as an effective mechanism to convert ocean wave energy directly into propulsion.The authors propose a novel setup whereby these foils can heave relative to the surface vehicle and, through the application of a power take off (PTO) system, can recover a proportion of the incoming wave energy.Experiments were performed to investigate the coupled response between a surface vehicle and submerged flapping foils within the context of generating power and propulsion from incoming waves onboard ASVs. Results show that the response of a surface vehicle with submerged flapping foils is particularly sensitive to design parameters such as the longitudinal location of the foils and the seakeeping characteristics of the surface vehicle.Through optimising the PTO system, this setup could recover a useful proportion of wave energy for ASV platforms