Mathematica: a system for doing mathematics by computer (2nd ed.)
Mathematica: a system for doing mathematics by computer (2nd ed.)
Benchmark problems for incompressible fluid flows with structural interactions
Computers and Structures
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The vortex method has been extended to account for blade flexibility, which is a potential source of unsteadiness in the flow past a wind turbine rotor. The code has been validated previously under the assumption of rigid blades. The aerodynamics method is based on the Goldstein model, which distributes the flow vorticity on rigid helicoidal surfaces defined uniquely by the flow parameters (tip speed ratio and average power extracted by the rotor) and the blade geometry (maximum radius and root lengths). The structure is treated as a beam with degrees of freedom in bending and torsion. The high twist of the wind turbine blades is responsible for induced velocities in the plane of the rotor as well as out of plane. A modal decomposition has been shown to be the most accurate and efficient approach for an implicit coupling of the structural and aerodynamics equations. Results for a homogeneous blade are presented for a low speed of 5m/s and yaw angles of 0^o, 5^o and 10^o and compared with rigid blade results and experiments of the National Renewable Energy Laboratory (NREL). The nonhomogeneous NREL blade has also been modeled and results are presented for V=8 and 10m/s at zero yaw that include the effect of the tower on the blade loading.