Scale Effects on Heave Plates for Floating Offshore Wind Turbines

An essential aspect of experimental campaigns in ocean basins is the extrapolation of results to prototype scale. In the case of “spar” or semi-submersible platforms for floating wind turbines, it is customary to use heave plates that reduce the heave motion and/or tune its period. As part of the Hiprwind project, it was decided to study the scale effects on the hydrodynamics of these elements. To this aim, models of one column of the platform, equipped with a plain heave plate, were built. This model is a simplified representation of the actual one, which incorporates an edge vertical flap. The scales were 1:20, 1:27.6, and 1:45.45, with the former leading to added mass values of the order of 300kg, becoming one of the largest model for which experiments with heave oscillations have been carried out. Decay tests starting from various amplitudes and forced oscillations tests were performed at a range of frequencies and operational and extreme KCs (range of motion). Results related to these tests will be discussed in the paper.