Numerical Simulation of a Wave-Powered Autonomous Underwater Vehicle Charging System

Wave energy converters (WECs) hold immense potential to provide electrical power for various applications, from
grid connections to remote sensors. One possibility within the "Powering the Blue Economy" initiative is generating
power for Autonomous Underwater Vehicles (AUVs). This can be achieved either through wave-powered charging
stations or by integrating WECs directly into the AUV design. The latter approach was employed in developing the
Platypus Prowler WEC, a WEC/AUV design created for the DOE/NOAA Ocean Observing Prize contest. This
system features a module that functions as a WEC when the AUV is oriented vertically (bow up), converting
mechanical energy into electrical energy via a drivetrain and generator. The WEC design includes three paddle arms
that fold down during transit and extend out in charging mode. These arms capture wave energy by oscillating due
to variations in net buoyant force and fluid loadings from the wave field. To evaluate and optimize the performance
of this system, numerical simulations using WEC-Sim were conducted. WEC-Sim employs the Morison load
approach to model the interaction between the WEC and dynamic waves, and the Boundary Element Model (BEM)
approach to calculate hydrodynamic response coefficients through a discretized panel mesh. This enables the
calculation of added mass, excitation, and radiation forces. Initially, system loading, and power output capabilities
were analyzed to optimize PTO damping. Following this, the system's performance was assessed across various
wave periods and heights to determine its capture width under different wave conditions. This provides valuable
insights into the potential of WECs to effectively harness wave energy for AUV charging.