Numerical Study of Flutter of a Two-Dimensional Aeroelastic System

Riccy Kurniawan

doi:10.1155/2013/127123

Abstract

Numerical Study of Flutter of a Two-Dimensional Aeroelastic System: This paper deals with the problem of the aeroelastic stability of a typical aerofoil section with two degrees of freedom induced by the unsteady aerodynamic loads. A method is presented to model the unsteady lift and pitching moment acting on a two-dimensional typical aerofoil section, operating under attached flow conditions in an incompressible flow. Starting from suitable generalisations and approximations to aerodynamic indicial functions, the unsteady loads due to an arbitrary forcing are represented in a state-space form. From the resulting equations of motion, the flutter speed is computed through stability analysis of a linear state-space system.

Highlights

Flutter is the dynamic aeroelasticity phenomenon whereby the inertia forces can modify the behaviour of a flexible system so that energy is extracted from the incoming flow
The flutter or critical speed VF is defined as the lowest air speed at which a given structure would exhibit sustained, simple harmonic oscillations
Wagner [2] obtained a solution for the so-called indicial lift on a thin aerofoil undergoing a transient step change in angle of attack in an incompressible flow

Summary

Introduction

Flutter is the dynamic aeroelasticity phenomenon whereby the inertia forces can modify the behaviour of a flexible system so that energy is extracted from the incoming flow. Theodorsen [1] obtained closed-form solution to the problem of an unsteady aerodynamic load on an oscillating aerofoil. This approach assumed the harmonic oscillations in inviscid and incompressible flow subject to small disturbances. Wagner [2] obtained a solution for the so-called indicial lift on a thin aerofoil undergoing a transient step change in angle of attack in an incompressible flow. The indicial lift response makes a useful starting point for the development of a general time domain unsteady aerodynamics theory. The main objective of this paper is to investigate the aeroelastic stability of a typical aerofoil section with two degrees of freedom induced by the unsteady aerodynamic loads defined by the Leishman’s state-space model

Aeroelastic Model Formulation

Results and Discussion

Conclusions