Experimental study of a new multi-column tension leg-type floating wind turbine concept

Abstract

Offshore deep-water region is rich in high-quality wind energy. Currently offshore floating wind turbine is the most potential equipment to exploit it. The relevant scaling laws need to be considered during the offshore floating wind turbine model test were analysed and a proper scaling methodology was established according to the loading conditions. The wave tank model test was conducted for the proposed new multi-column tension leg-type floating wind turbine concept in SKLOE’s wave basin with the geometric scaling factor of 50 according to the main dimensions and environmental conditions. By using a modified blade design based on the same wind turbine thrust coefficient, the aerodynamic Reynolds number scaling effect was dissimilated during the model test. Still water tests, white noise wave tests and combined wind wave and current tests were carried out. During the combined wind, wave and current tests, both the turbine operating (DLC01-05) and parked conditions (DLC06, DLC07) were investigated. To identify the dominate load of the dynamic responses, each design load case was further separated into four different sub-load cases: wind only case, wave only case, current only case and combined load case. Global response variables including platform motion, tendon tension, rotor thrust, and nacelle accelerations were examined. In summary, the proposed WindStar TLP system showed relatively small dynamic motion responses to environmental loads due to its natural frequencies are well kept away from the dominant wave periods and the tendons still holds a sufficient safety factor, and the minimum tendon tensions remain positive under all the selected DLCs. The model testing results could serve as a reference for the further research.