Analytical and experimental modelling of non-linear aeroelastic effects on prismatic bodies

This paper deals with the aeroelastic instability and non-linear post-critical behaviour of a two degree-of-freedom oscillatory system. The main goal of the study is an introduction of a realistic non-linear theoretical model making possible a detailed non-linear analysis of post-critical states of an aeroelastic system. Two component self-induced vibration of a body is described by a system of two simultaneous non-linear differential equations. The coupling of the resultant motion is due to linear and non-linear aeroelastic effects only, while the elastic forces are taken independent. Differential system is auto-parametric and represents a combination of Rayleigh or Van der Pol with Duffing types of differential equations. The qualitative analysis is based on the uplift coefficients and torsional moments as the functions of the flow velocity and structural response components. The effects of non-linearities are tested on the model where the motion of one degree of freedom is prevented. The analysis is verified experimentally by the new generation technique allowing excessive amplitudes of the oscillation.