Abstract
Large modern wind turbine blades are highly flexible structures that are susceptible to severe aeroelastic vibrations under turbulent wind conditions. These dynamic oscillations accelerate fatigue damage and reduce the operational lifespan of the structural components. This study investigates the application of Tuned Liquid Column Dampers (TLCDs) integrated within the blade cavity to passively control the first flapwise vibration mode. A coupled aero-servo-elastic mathematical model of a 5 MW wind turbine blade equipped with a TLCD is developed, incorporating Kaimal-spectrum turbulent wind fields and Blade Element Momentum (BEM) theory. Scaled experimental testing in a boundary-layer wind tunnel was conducted to validate the numerical model. The performance of the TLCD is evaluated under various turbulence intensities and wind speed profiles. Results demonstrate that the optimized TLCD achieves a reduction of up to 34.5% in peak flapwise displacement and a 28.2% reduction in the root bending moment standard deviation under extreme turbulent conditions. Furthermore, parametric studies indicate that the liquid mass ratio and orifice damping ratio are critical design parameters, with an optimal liquid mass ratio of 1.5% providing the most cost-effective damping performance. This research provides a robust framework for implementing passive liquid dampers in next-generation, ultra-long wind turbine blades to mitigate fatigue and enhance structural reliability.
