Flutter Analysis of Two-Dimensional and Two-Degree-of-Freedom MBB A-3, CAST 7, an TF-8A Supercritical Airfoils in Small-Disturbance Unsteady Transonic Flow

摘要

Flutter analyses at transonic Mach numbers are performed for three supercritical airfoils: (1) MBB A-3; (2) CAST 7; and (3) TF-8A wing section at the 65.3% semispan station. For all airfoils, two degrees of freedom, pitching and plunging, are considered. The unsteady aerodynamic data are obtained by using two separate transonic aerodynamic computational codes: (1) LTRAN2 based on the time integration method and (2) STRANS2 and UTRANS2 based on the harmonic analysis method. The steady aerodynamic results are shown in the form of upper and lower surface pressure curves. The unsteady aerodynamic coefficients are obtained for various values of low reduced frequencies by pitching the airfoils about the quarter chord axis. Unsteady results are presented as plots of unsteady coefficients versus angle of attack for the MBB A-3 airfoil and versus Mach number for the CAST 7 and TF-8A airfoils.