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Stability of large horizontal-axis axisymmetric wind turbinesThe stability of large horizontal axis, axi-symmetric, power producing wind turbines was examined. The analytical model used included the dynamic coupling of the rotor, tower and power generating system. The aerodynamic loading was derived from blade element theory. Each rotor blade was permitted tow principal elastic bending degrees of freedom, one degree of freedom in torsion and controlled pitch as a rigid body. The rotor hub was mounted in a rigid nacelle which may yaw freely or in a controlled manner. The tower can bend in two principal directions and may twist. Also, the rotor speed can vary and may induce perturbation reactions within the power generating equipment. Stability was determined by the eigenvalues of a set of linearized constant coefficient differential equations. All results presented are based on a 3 bladed, 300 ft. diameter, 2.5 megawatt wind turbine. Some of the parameters varied were; wind speed, rotor speed structural stiffness and damping, the effective stiffness and damping of the power generating system and the principal bending directions of the rotor blades. Unstable or weakly stable behavior can be caused by aerodynamic forces due to motion of the rotor blades and tower in the plane of rotation or by mechanical coupling between the rotor system and the tower.
Document ID
19810003935
Acquisition Source
Legacy CDMS
Document Type
Thesis/Dissertation
Authors
Hirschbein, M. S. (NASA Lewis Research Center Cleveland, OH, United States)
Young, M. I. (Delaware Univ. Newark, United States)
Date Acquired
September 4, 2013
Publication Date
January 1, 1980
Subject Category
Structural Mechanics
Report/Patent Number
E-633
NASA-TM-81623
Meeting Information
Meeting: Miami Conf. on Alternative Energy Sources,
Location: Miami, FL
Country: United States
Start Date: December 15, 1980
End Date: December 17, 1980
Accession Number
81N12446
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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