Report of a towing test campaign of a scaled wind turbine

For the full physical testing of FOWTs in combined wind and waves, it is necessary to generate good quality wind in order for the modeled wind turbine rotor to deliver the desired scaled down thrust. Limiting the turbulence to an acceptable level for steady wind tests can only be done at the price of important loss of output wind speed for fan based generator. It is not precisely known what is acceptable for the level of turbulence during the testing of FOWTs? Also, it is very difficult to generate a uniform wind field in a basin. The idea at the origin of this work was to think of a way to avoid or minimize these issues. MARIN carried out towing tests of a turbine made with the same rotor as it has been used for testing in combined waves and wind conditions. These data could be compared with the results of previous model tests in the Offshore Basin with the same rotor in a generated wind field. In this way, the effects of turbulence and slight non-uniformity of the wind field on the performance of this scaled down rotor in a fan generated wind field could be evaluated.