Open AccessStability investigation of an airfoil section with active flap control
Author(s) -
Bergami Leonardo,
Gaunaa Mac
Publication year - 2009
Publication title -
wind energy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.743
H-Index - 92
eISSN - 1099-1824
pISSN - 1095-4244
DOI - 10.1002/we.354
Subject(s) - airfoil , trailing edge , flutter , aerodynamic center , aerodynamics , structural engineering , engineering , control theory (sociology) , helicopter rotor , aerodynamic force , leading edge , aileron , aeroelasticity , angle of attack , aerospace engineering , pitching moment , computer science , rotor (electric) , mechanical engineering , artificial intelligence , control (management)
Abstract This work presents a method to determine flutter and divergence instability limits for a two‐dimensional (2‐D) airfoil section fitted with an actively controlled trailing edge flap. This flap consists of a deformable trailing edge, which deformation is governed by control algorithms based on measurements of either heave displacement, local angle of attack or aerodynamic pressure difference measured over the airfoil. The purpose of the controlled deformable flap is to reduce fluctuations in the aerodynamic forces on the airfoil, which, according to recent studies, have a significant potential for fatigue load alleviation. The structural model of the 2‐D airfoil section contains three degrees of freedom: heave translation, pitch rotation and flap deflection. A potential flow model provides the aerodynamic forces and their distribution. The unsteady aerodynamics are described using an indicial function approximation. Stability of the full aeroservoelastic system is determined through eigenvalue analysis by state–space formulation of the indicial approximation. Validation is carried out against an implementation of the recursive method by Theodorsen and Garrick for ‘flexure–torsion–aileron’ flutter. The implemented stability tool is then applied to an airfoil section representative of a wind turbine blade with active flap control. It is thereby observed that the airfoil stability limits are significantly modified by the presence of the flap, and they depend on several parameters: flap structural characteristics, type of control, control gain factors and time lag. Copyright © 2009 John Wiley & Sons, Ltd.