AN EXPLICATION OF AIRFOIL SECTION BENDING-TORSION FLUTTER

Abstract

This thesis examines the dynamic instability known as flutter using a two-degree-of-freedom airfoil section model in both quasi-steady and unsteady flow. It explains the fundamental forces and moments involved in the bending-torsion flutter of an airfoil section, and demonstrates a solution method for determining the critical flutter frequency and speed for both flow cases. Additionally, through the use of a programmed Mathcad 11 worksheet, it evaluates the flutter characteristics of six example sections, illustrating the effects of the elastic, inertial and aerodynamic properties of an airfoil section. For each section, a parametric study of the effect of the section Center of Gravity position along the section chord is performed. The flutter frequency and speed are calculated using both quasi-steady and unsteady aerodynamic forces and moments, and the results compared. Software used was MathSoft Mathcad 11, Microsoft Word and Intergraph Smart Sketch LE.