Development of a hardware-in-the-loop wind tunnel setup to study the aerodynamic response of floating offshore wind turbines

Abstract

In floating wind turbines, wind and wave excitation leads to motions of the floater that affect the rotor aerodynamic loads, which in turn influence the motion of the floater, in a highly coupled way. Numerical design tools can sometimes fail to predict certain aerodynamic phenomena, and therefore experimental testing is essential for tuning and validating these codes. Hybrid testing in wind tunnels, by measuring aerodynamic loads on a physical scale rotor under high-quality wind while numerically reproducing and actuating the floater motions, allows for higher fidelity in the reproduction of the aerodynamics compared to traditional wave basin tests. This work presents the development of a hybrid hardware-in-the-loop setup designed to study the aerodynamic response of floating wind turbines in wind tunnels. A scale model of a multi-megawatt floating wind turbine is mounted on top of a 6-degree-of-freedom hexapod robot. The full coupling of aerodynamic and floater dynamics is obtained with a hardware-in-the-loop approach with force-feedback–motion-actuation architecture. The rotor loads measured on the physical rotor are fed into a floater numerical simulator, which calculates the motion in real time and actuates it through the hexapod. Key outcomes include the development of a hardware-in-the-loop numerical model with an aerodynamic load estimation method to cope with scaling effects and the assessment of the floater simulator, the force estimation, and the measurement-actuation chain. The aerodynamic effects on the motion response are preliminarily investigated on a 10 MW floating concept, allowing the increase in pitch, yaw, and surge damping to be quantified through measured loads. The capability of testing combined wind and wave cases is also demonstrated, setting the framework for future studies.