Experimental and Numerical Study of a New Dynamic Phenomenon for Two-bladed Wind Turbines

In this paper the dynamics of a two-bladed turbine is investigated numerically as well as experimentally with respect to how the turbine frequencies change with the rotor speed. It is shown how the turbine frequencies of a two-bladed rotor change with the azimuthal position at standstill and how the frequencies start whirling during rotor rotation.

The whirling for two-bladed rotors change with multiple P contributions and not only ±1P as is previously seen for three-bladed wind turbine rotors. A three-bladed turbine was also analyzed in similar way and results were compared. This turbine was investigated both in a perfect isotropic condition where all blades have identical properties as well as an imbalanced edition where one blade had increased mass.