Flutter Analysis of Two-Dimensional and Two-Degree-of-Freedom Airfoils in Small-Disturbance, Unsteady Transonic Flow

Résumé du livre

Flutter analyses are performed for an NACA 64A006 and an NACA 64A010 airfoil by simultaneously using two transonic aerodynamic computational codes: (1) STRANS2 and UTRANS2 based on the relaxation method and (2) LTRAN2 based on the indicial and time-integration methods. Flutter results are obtained as plots of flutter speeds and the corresponding reduced frequencies versus one of the four parameters; airfoil-air mass ratio; position of the mass center; position of the elastic axis; and free stream Mach number. On each figure, several sets of curves for different values of plunge-to-pitch frequency ratios are shown simultaneously. The flutter results obtained by using relaxation and the indicial methods are, in general, in good agreement. The present flutter results for a special case of a thin parabolic airfoil at a low transonic Mach number of 0.7 compare favorably with that obtained by using linear flat plate theory. The trend of each flutter curve and the effect of each parameter are discussed in detail.