Preliminary Assessment Of A Wave Energy Conversion Principle, Using Fully Enclosed Multi-Axis Inertial Reaction Mechanisms

A novel concept of Wave Energy Converters is considered, composed from a class of fully enclosed, appropriate, internal body mechanisms, which provide inertial reaction against any multi-axis, multi-direction motion of an external vessel. This ensures maximum wave energy capture in comparison to other types of wave energy converters, based on internal reaction mechanisms. The internal bodies are suspended from the external vessel body in such an appropriate geometrical configuration, resulting to a linear trajectory for the center of the mass of the suspended body with respect to the external vessel. Moreover, the suspension geometry ensures a quite simple and robust technological implementation, removing the restrictions of other linear, pendulum or gyroscopic variants of inertial reacting bodies. Furthermore, the mass and the inertia distribution of the internal body is optimized for the maximal conversion and storage of the wave energy. As a result, the dynamic behavior of the internal body assembly, is essentially that of an equivalent vertical physical pendulum. However, the resulting equivalent pendulum length and inertia can far exceed those achieved by an actual technical implementation of other pendulum variants, resulting to a significant reduction of the suspended mass. A preliminary design of such a mechanism is considered and a simple equation is derived to estimate the power conversion potential of such a mechanism, as a function of the main geometrical and inertial design parameters. Then, the behavior of the mechanism is evaluated under a combination of surge and pitch excitations.