Jean-Roch Nader

A finite element model for efficiency of a moored floating OWC device in regular waves

Hydrodynamic characteristics of floating OWC can be quite difficult to predict especially when a strong coupling is present between the chamber pressure and the device movements. Mooring properties, and air pressure inside the chamber can also considerably influence the motion of the device and therefore the energy output. A newly developed 3D finite element model based on the linear wave theory has been applied to a cylindrical type OWC device. The study focused principally on the effects of the mooring restoring force and pressure pneumatic damping in the chamber total volume flux and energy conversion of the device. Results show that properly chosen parameters could effectively increase the efficiency band width of such devices. Copyright

On the efficiency of Oscillating Water Column (OWC) devices in converting ocean wave energy to electricity under weakly nonlinear waves

Oscillating Water Column (OWC) devices are regarded as one of the most promising systems developed to harness ocean wave energy. In this paper, we present some preliminary results of our most recent effort in the research of trying to improve the efficiency of OWCs with a focus on the comparison of incident waves being in the linear and weekly nonlinear regimes. As the results show, the counted-in nonlinearity at the second order could contribute to more than a 50% increase in the maximum mean power output.Copyright

System identification of a floating oscillating water column wave energy converter

One of the objectives of studies regarding the performance of floating oscillating water column (OWC) wave energy conversion devices is the prediction of the heave motion of the chamber and the water column. This paper presents a method to evaluate the parameters involved in the dynamics of partially submerged bodies in order to predict the coupled movement of the chamber and the water column in the frequency domain. System identification was performed and a lumped parameter model of the heave motions of a floating OWC was proposed. A novel approach utilising the reverse SISO method was employed to allow frequency dependent parameters for both the floating structure and the oscillating water column to be determined from several forced vibration experiments. Experimental results under forced vibration and wave excitation agree reasonably well with the dynamic model established.© 2011 ASME