Abstract
This paper deals with the problem of the aeroelastic stability of a typical aerofoil section with two degrees of freedom induced by 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. The sensitivity analysis of the aeroelastic stability boundaries to the structural parameter is evaluated. The results show that the parameter with the greatest influence on flutter speed is the center of gravity.
Highlights
Flutter is the dynamic aeroelasticity phenolmenon whereby the inertial forces can modify the behavior of a flexible system so that energy is extracted from the incoming flow
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 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
Summary
RESEARCH METHODFlutter is the dynamic aeroelasticity phenolmenon whereby the inertial forces can modify the behavior 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 in-viscid 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. A practical way to tackle the indicial response method is through a state-space formulation in the time domain, as proposed, for instance by Leishman and Nguyen [3]
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