Study of Transonic Flutter of a Two-Dimensional Airfoil Using the U-g and p-k Methods (Une Etude sur les Vibrations Aeroelastiques en Regime Transsonique d'Un Profil Aerodynamique Bidimensionnel au Moyen des Methodes U-g et p-k)

摘要

Transonic flutter of a NACA64A006 airfoil undergoing plunging and pitching oscillations is studied using the U-g and p-k methods. The aerodynamic coefficients are calculated using an improved version of an ONERA unsteady transonic aerodynamics code which include the second time derivative term of the velocity potential in the governing equation. Comparisons with LTRAN2-NLR show good agreement up to and in some cases exceeding kc = 0.4, except for the pitching moment curves at the transonic dip Mach number of 0.85. All flutter results are presented for M = 0.85. The p-k method gives flutter speeds identical to those from the U-g method. Subcritical damping ratios using the U-g method with Frueh's and Miller's damping formula are quite close to those obtained from the p-k method, especially for large values of the airfoil-air mass ratio. Response of the airfoil to externally applied forces and moments is studied using the p-k method and a viscous damping model for coupled motions.