Experimental Uncertainty Analysis of an OWC Wave Energy Converter

This paper presents a practical example of an uncertainty analysis applied to the results of an oscillating water column (OWC) wave energy converter (WEC) model test experiment in regular waves. The 1:20 scale OWC device equipped with a porous mesh power takeoff (PTO) system was integrated into a fully reflective breakwater and installed in the Australian Maritime College Model Test Basin. Using phase-averaging as a data analysis technique, device performance in terms of capture width was determined across the frequency range tested, using probe data of the incident wave elevations, and the resulting wave elevations and pressure inside the OWC chamber. This paper is devoted to evaluating the uncertainty of this data. Type A uncertainty (statistical means via repeat observations) was determined through a series of repeat observations, whereas Type B uncertainty (non-statistical means) was determined using sensor calibration data and through regression analysis. Total uncertainty results include < ± 2% for all wave probe data, < ± 11 % for pressure, ± 22% for damping, producing a total uncertainty of ± 30% for the mean power of the device. This large uncertainty in power is because the calculation is a function of damping and pressure that both eventuated to relatively large uncertainty. This study highlights the importance of presenting experimental results with a description of the uncertainties involved.