Improved Understanding of Transonic Flutter: A Three-Parameter Flutter Surface

This is the authors' abstract. We don't add key points for this paper.

An understanding of transonic flutter is often critical for high-speed aircraft development. A presentation of the transonic flutter velocity as a function of the Mach number and mass ratio is shown here to provide many advantages. Such a presentation offers new insights when comparing computational and wind-tunnel flutter results. The benefits of such a presentation are also evident in parameter studies. Finally, the subject of flutter similarity rules for airfoils of different thicknesses is also addressed. Nomenclature a = nondimensional location of airfoil elastic axis, e/b a0 = stagnation speed of sound b, c = semichord and chord, respectively e = location of airfoil elastic axis, measured positive aft of airfoil midchord h = airfoil plunge degree of freedom (DOF) Iα = second moment of inertia about elastic axis Kh, Kα = airfoil plunge stiffness and torsional stiffness about elastic axis, respectively L = aerodynamic lift M = freestream Mach number Mea = aerodynamic moment about elastic axis m = airfoil sectional mass rα = radius of gyration of airfoil about elastic axis; r 2 α is identical to Iα/mb 2