Seyyed A. Sina; B. Balanian
Abstract
Multi-Megawatt wind turbines have long, slender and heavy blades that can undergo extremely wind loadings. Good understanding of the modal dynamics of these large machines is of great priority. In this paper, modal dynamics of NREL 5 MW wind turbine is investigated. To this aim, FAST software has been ...
Read More
Multi-Megawatt wind turbines have long, slender and heavy blades that can undergo extremely wind loadings. Good understanding of the modal dynamics of these large machines is of great priority. In this paper, modal dynamics of NREL 5 MW wind turbine is investigated. To this aim, FAST software has been implemented. Vibration characteristics of blades, tower and whole wind turbine machine is extracted. To examine the effects of wind velocity, two operating conditions of machine have been considered. Namely: normal operating condition at rated wind velocity and rated rotor speed and the other, parked condition with fixed rotor at the wind velocity equal to rated wind velocity. Blades root bending moments (both in plane and out of plane) and tower bending moments (both longitudinal and lateral) are extracted. Frequency spectrum of the results is utilized as a tool to study the effects of each vibration mode on wind turbine dynamics in each of aforementioned operating conditions. It is shown that tower vibration during normal operation is highly influenced from blade edge-wise bending mode. On the other hand, during parked condition the effects of flap-wise bending modes become more dominant. The results are expected to offer better predictions of the vibrational behavior of large wind turbines.
Seyyed A. Sina
Abstract
Multi-Megawatt wind turbines have long, slender and heavy blades that can undergo extremely wind loadings. Aeroelastic stability of wind turbine blades is of great importance in both power production and load carrying capacity of structure. This paper investigates the aeroelastic stability of wind turbine ...
Read More
Multi-Megawatt wind turbines have long, slender and heavy blades that can undergo extremely wind loadings. Aeroelastic stability of wind turbine blades is of great importance in both power production and load carrying capacity of structure. This paper investigates the aeroelastic stability of wind turbine blades modeled as thin walled composite box beam, utilizing unsteady incompressible aerodynamics. The structural model incorporates a number of non-classical effects such as transverse shear, warping inhibition, non-uniform torsional model and rotary inertia. The unsteady incompressible aerodynamics based on Wagner’s function is used to determine the aerodynamic loads. Governing differential equations of motion are obtained using Hamilton’s principle and solved using extended Galerkin’s method. The results obtained in this paper, related to clarification of the effects of angular velocity and wind speed on the aeroelastic instability boundaries of the thin-walled composite beams. The obtained results are expected to be useful toward obtaining better predictions of the aeroelastic behavior of composite rotating blades.