Flutter Analysis of a Two-Dimensional and Two-Degree-of-Freedom Supercritical Airfoil in Small-Disturbance Unsteady Transonic Flow.
- 1 March 1980
- report
- Published by Defense Technical Information Center (DTIC)
Abstract
Flutter analysis is performed for a MBB A-3 supercritical airfoil at transonic Mach numbers. 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 and tabulated for various values of low reduced frequency by pitching the MBB A-3 airfoil about the quarter chord axis. For the case of zero mean angle of attack, the coefficients obtained by the two computer codes are directly compared and discussed. At design Mach number of 0.765 and zero mean angle of attack, flutter results are obtained by both methods and compared. They are presented as plots of flutter speed and the corresponding reduced frequency vs. one of the four parameters: airfoil - air mass ratio; position of mass center; position of elastic axis; and plunge-to-pitch frequency ratio.Keywords
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