An innovative tank testing method to efficiently characterise wave energy converters. (Septembre 2021)

Tank testing is an integral part of wave energy converter (WEC) development. It allows the development team to gather data about their concept early in the development cycle before having sophisticated simulation tools, and the assumptions and limitations of tank testing are different from the ones required by hydrodynamic modelling. The tank testing objective are traditionally reached using a combination of simple regular waves to characterise the device, and realistic irregular waves which replicate conditions close to future deployment environment. Characterising the device behaviour requires either multiple regular wave runs, and the frequency resolution of irregular seas required to provide realistic characteristics is such that it imposes long tank runs. Both methods are time consuming and limiting when the objective is to quickly sieve through numerous device configurations. This article presents an innovative sea state, Ir0, dedicated to characterise efficiently WEC configurations. It was tested during the Seaturns tests at the Aalborg basin in February 2020. Composed of 25 components, Ir0 has a waveheight H_S = 2.1 m and a period T_E = 10.0 s at equivalent full scale. At tank scale, Ir0 has a repeat period of 256 s only, allowing for quick testing and multiple repetitions. The Response Amplitude Operators are obtained from regular waves testing and Ir0 and are compared to the device behaviour in irregular waves. It shows that the Ir0 is accurate and provide a truthful characterisation of the concept. Ir0 was used to characterise 51 configurations during the two weeks testing.