Aeroelastic Wind Tunnel Testing of Yawed Wind Turbine Rotor with Teetering Hub

This paper presents an experimental investigation into the aeroelastic behavior of an innovative wind turbine design featuring a downwind two-blade rotor with a teetering hub mounted on a tower with adjustable tilt. The rotor model incorporates two sets of elastic blades—stiff and flexible—for scaling purposes, each instrumented with strain gauges and accelerometers. Ground and wind tunnel tests were conducted to analyze the aeroelastic response. Static deformation tests revealed discrepancies between measured and numerically predicted displacements. Maximum displacements near the tip exceeded numerical predictions by 14% and 31% for flexible and stiff blades respectively. Frequency differences between measured and numerically simulated elastic modes ranged from 0.5% to 18% for both blade sets, as determined by ground vibration tests. No dynamic aeroelastic instability was observed during wind tunnel tests, as rotational speed harmonics dominated the rotor’s response. The tower tilt angle was found to be the dominant parameter in static response, while the tip speed ratio in conjunction with rotational speed emerged as the most crucial parameters in the dynamic response. Overall, this research provides valuable insights into the aeroelastic behavior of yawed, two-blade wind turbine rotors with flexible blades and a teetering hub and could aid in the refinement of numerical models that incorporate elastic blades.