Vibration Characteristics of an Experimental Wind Turbine with a 15 m Teetered Rotor

Vibration spectra of the experimental 15m wind turbine of the Mechanical Engineering Laboratory were obtained in field operation to clarify the vibration characteristics of general teetered-rotor wind turbines. To investigate the causes of steady vibration, step response tests were also conducted, where excitations were made with the disk brake located at the high-speed shaft. As a result, a Campbell diagram for the system has been established. The tower-bending resonance with one-per-rev and two-per-rev excitations of the rotor, as well as the transmission-torsion resonance with two-per-rev excitation, has been observed. It has also been found that the one-per-rev gravitational force is predominant for the blade chordwise bending and that various n-per-rev components due to wind speed variation can be seen on the blade flapwise bending.