**Author details**

**Figure 30.** Damping coefficient against rotational speed and flutter frequency against rotor speed

118 Advances in Wind Power

**Figure 31.** Flutter simulation with ANSYS-CFX at 1) 1.8449 s, 2) 1.88822 s and 1.93154s

We present here the results obtained for the same case study using ANSYS-CFX. The fre‐ quency of the movement using Matlab is 6.5 Hz while that using the ANSYS-CFX model is 6.325 Hz compared with the experimental value of 7.1Hz [35]. Furthermore, the amplitudes of vibration are very close as well as the trend of the oscillations. For the points identified as 1, 2 and 3 on the flutter illustration, we illustrate the relevant flow over the airfoil. The maxi‐ mum air speed at moment noted 1 is 26.95 m/s. We note such a velocity difference over the airfoil that an anticlockwise moment will be created which will cause an increase in the an‐ gle of attack. Since the velocity, hence, pressure difference, is very large, we note from the flutter curve, that we have an overshoot. The velocity profile at moment 2, i.e., at 1.88822s shows a similar velocity disparity, but of lower intensity. This is visible as a reduction in the gradient of the flutter curve as the moment on the airfoil is reduced. Finally at moment 3, we note that the velocity profile is, more or less, symmetric over the airfoil such that the mo‐ ment is momentarily zero. This corresponds to a maximum stationary point on the flutter

Drishtysingh Ramdenee1,2, Adrian Ilinca1 and Ion Sorin Minea1

1 Wind Energy Research Laboratory, Université du Québec à Rimouski, Rimouski, Canada

2 Institut Technologique de la Maintenance Industrielle, Sept Îles, Canada
