Gyroscopically enhanced vertical axis pendulum for wave energy conversion

Abstract

The vertical axis pendulum is a type of point absorber device which can absorb wave energy from a width exceeding the physical width of the device. Mechanical power is harvested from the rotation of the pendulum, in which the pivot point is directly connected to the generator. In this paper, a new concept of the vertical axis pendulum device is proposed by adding a spinning flywheel to create a gyroscopic effect with the aim to enhance the motions of the pendulum. In the vertical axis of the pendulum, the reaction torque from the power take off (PTO) is included as a linear function of the pendulum rotation velocity to model the mechanical power conversion into electrical power. The initial spinning velocity of the flywheel is used as the parameter to obtain the maximum energy in the PTO. To demonstrate the effect of adding a flywheel to the pendulum system, two models are simulated and compared, i.e. a classical vertical axis pendulum and a ‘gyroscopic-pendulum’. The results of the comparison are presented in terms of the pendulum motions and the PTO converted power.