Abstract
The present study investigated physical phenomena related to stall-induced vibrations potentially existing on wind turbine
blades at standstill conditions. The study considered two-dimensional airfoil sections while it omitted three-dimensional
effects. In the study, a new engineering-type computational model for the aeroelastic response of an elastically mounted
airfoil was used to investigate the influence of temporal lag in the aerodynamic response on the aeroelastic stability in deep
stall. The study indicated that even a relatively low lag significantly increases the damping of the model. A comparison
between the results from a model with lag imposed on all force components with the results from a model with lag imposed
exclusively on the lift showed only marginal difference between the damping in the two cases. A parameter study involving
positions of the elastic hinge point and the center of gravity indicated that the stability is relatively independent of these
parameters. Another parameter study involving spring constants showed that the stability of each mode is dependent only
on the spring constant acting in the direction of the leading motion of the mode. An investigation of the influence of the
added mass terms showed that only the pitch-rate and flapwise-acceleration terms have any influence on the stability. An
investigation of three different profiles showed that the stability is heavily dependent on the aerodynamic characteristics
of the profiles—mainly on the lift. It was also shown that only the edgewise mode is unstable in deep stall. Moreover,
independent of the amount of temporal lag in the aerodynamic response of the model, the inflow-angle region in the vicinity
of 180ı remains unstable in the edgewise mode. Therefore, this inflow-angle region may create stability problems in real
life. The other type of vibrations potentially present at standstill conditions is vortex-induced, being outside the scope of
the present study. Copyright © 2014 John Wiley & Sons, Ltd.
Original language | English |
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Journal | Wind Energy |
Volume | 18 |
Issue number | 3 |
Pages (from-to) | 515–527 |
Number of pages | 13 |
ISSN | 1095-4244 |
DOIs | |
Publication status | Published - 2015 |
Keywords
- Standstill conditions
- Aerodynamics
- Aeroelasticity
- Deep stall
- Engineering model
- Blade vibration
- Stall-induced vibration
- Stall-flutter