Abstract
Multi-rotor system (MRS) wind turbines can be a competitive alternative to large-scale wind turbines. In order to address the structural behavior of the turbine tower, an in-house aeroelastic tool has been developed to study the dynamic responses of a 2xNREL 5MW twin-rotor configuration wind turbine. The developed tool has been verified by comparing the results of a single-rotor configuration to a FAST analysis for the same simulation conditions. Steady flow and turbulent load cases were investigated for the twin-rotor configuration. Results of the simulations have shown that elasticity of the tower should be considered for studying tower dynamic responses. The tower loads, and deformations are not straightforward with the number of rotors added. For an equivalent tower, an additional rotor will increase the tower-top deflection, and the tower-base bending moment both in the fore-aft direction will be more than doubled. The tower torsional stiffness becomes a crucial factor in the case of a twin-rotor tower to avoid a severe torsional deflection. Tower natural frequencies are dominant over the flow conditions in regards to the loads and deflections.
Highlights
With the world’s high demand of energy, and the limitation of the amount of fossil fuels, renewable energies have become a field of interest for many researchers
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Two load cases were investigated for the twin rotor configuration; one is in a steady wind condition, and the other is in cases turbulent conditions
Summary
With the world’s high demand of energy, and the limitation of the amount of fossil fuels, renewable energies have become a field of interest for many researchers. The world’s largest wind turbine has a 12 MW capacity, and a 107-meter blade length [2] With this large size comes big challenges, such as the huge transportation and installation cost of extremely large wind turbines and the severe structure dynamic loads on the blades and the tower, as well as the need to develop each component, including the blade, bearing, generator, gearbox, etc. Energies 2019, 12, 1881 used to construct the rotors have a higher strength to weight ratio With those advances in the materials technology, MRS is a promising alternative to large-scale wind turbines. The present tool is used to model a twin-rotor wind turbine, with two coplanar rotors placed on a T-shaped tower This tool can be later extended to model support structures for different configurations of MRS.
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