WER-25: Aeroelastic analysis of the NASA MOD-0 100 kw wind turbine with aileron controlled blade tip
Abla, M. and B.J. Brock. Edited by B.S. Liebst and W.H. Wentz. Aeroelastic analysis of the NASA MOD-0 100 kw wind turbine with aileron controlled blade tip. Wind Energy Report no.25. Wichita State University. Center for Energy Studies, 1984, 157 p.
An aeroelastic analysis was conducted to determine the design requirements for the aileron control on the NASA MOD 0 100 KW wind turbine to prevent flutter or divergence. The configuration of the ailerons was 2~1 chord over the outboard 30% span of the blades. The results of the analysis shows that either rotational stiffness about the aileron hinge line must be maintained or mass balancing is required to prevent flutter. A 10 HZ hinge stiffness (5,621 IN-LB/RAD per side) or 60 IN-LB of mass balance added ahead of the hingeline at the tip is sufficient to prevent flutter under all operating conditions. In addition, a vibration analysis of the blade was performed to determine if any of the resonant frequencies coincide with any of the frequencies of the potential forcing functions. The only mode that appears potentially troublesome is the first "symmetric" (cantilevered) bending mode. It comes close to the 2P (twice per revolution) excitation frequency at 40 RPM. If this frequency is reduced because of joint flexibility where the blade joins the hub, there may be a frequency coincidence with the strong 2P excitation caused by the blade passing through the wake behind the tower.