Non-dimensional analysis for matching an impulse turbine to an OWC (oscillating water column) with an optimum energy transfer

OWC (Oscillating water column) wave power plants are widely used in ocean wave energy conversion. It is universally accepted that for a good efficiency of the plant, the turbine and the chamber should match each other according to the wave climate site. In this work an alternative methodology is presented for coupling the chamber and the turbine efficiently, carrying out a whole dimensional analysis of the OWC plant. Basically, the wave data and the chamber geometry are the input data. The behaviour of the chamber is numerically simulated. From the numerical results, the optimum damping could be identified for every wave condition. Once the optimum chamber damping is found, the objective is to determine which turbine matches this damping. Numerical results, based on the quasi-steady assumption, were used to simulate turbine performance under periodic conditions. The calculation of the diameter is based on the damping caused by the turbine on the OWC, whereas the rotational speed is fixed to maximize the turbine mean efficiency. Furthermore, this methodology is worked out to compare the size and the rotational speed of different kinds of turbines. Finally, the influence of sea state changes on the parameters of the optimum turbine is also studied.