D. J. Malcolm, Engineering Structures, April 1988
A method is presented for the frequency response analysis of a Darrieus rotor wind turbine subject to turbulent flow. A number of time series vectors of longitudinal and lateral turbulent velocities are generated and the interaction with a two-bladed rotor is carried out with a double multiple streamtube model. The resulting time domain loads are transformed into the frequency domain in terms of components of a real set of eigenvectors of the rotor.
T.G. Carne, D.R. Martinez, S.R. Ibrahim, Sandia National Laboratories, 1983
A new testing technique and the Ibrahim time domain (ITD) modal identification algorithm have been combined, resulting in a capability to estimate modal parameters for rotating blade systems. This capability has been evaluated on the Sandia two-meter, vertical-axis wind turbine. Variation in modal frequencies as a function of rotation speed has been experimentally determined from 0 rpm (parked) to 800 rpm. Excitation of the rotating turbine was provided by a scheme which suddenly released a pretensioned cable, thus plucking the turbine as it rotated. The structural...
David Malcolm, for Wind Harvest International, December 2017
K. McLaren, S. Tullis and S. Ziada, McMaster University, 2007
The motivation for this project arose from an expected vibration source of a small-scale vertical axis wind turbine currently undergoing field-testing. The turbine consists of three 3-metre long vertically aligned blades each fixed to the central shaft by two horizontal arms and separated from one another by an angle of =120º. The blade profile is a NACA 0015 with a chord length of 0.4 metres fixed at zero angle of attack to the support arms. The turbine optimally operates at a blade-tip speed ratio (the ratio of the blade rotational velocity to the ambient wind velocity) of 1.6. As the blades turn about the...