Dynamic instability analysis of aeroelastic systems with application to aircraft wings

Abstract

In this research, a set of computational algorithms have been developed to obtain a solution for steady and unsteady aeroelastic effects with specific applications to rectangular and swept aircraft wings. The solution includes calculation for the dynamic response and prediction for the occurrence of aeroelastic instability. Two aircraft wing models, under different combinations of flight conditions, were used in testing. Good results that match with those obtained in the lab have been observed, except in certain conditions where severe external conditions, such as shocks, flow separation, or transonic flow occurred. The results were also validated with multiple computational methods. For instance, the pressure coefficient, Cp, calculated with vortex lattice was also calculated with Woodward's method and showed good match. For the unsteady flow, the calculated pressure coefficient and phase angle were compared with the measured values obtained in the lab, and the calculated and experimental results were very close. The generalized aerodynamic force function (QRS) was determined using two different schemes: a direct formula using the interpolation technique and using the downwash vectors. Both schemes produced very close results. The transfer function was calculated using direct and closed form solutions, producing identical results. The instability calculation showed very close match: for case 3A, the flutter point occurred at dynamic pressure, frequency, and flutter velocity of 20.933 Hz, 0.9 Psi, and 566 fps, respectively, compared with measured values of 20.38 Hz, 0.924 Psi, and 565.8 fps. For case 3B, the results showed flutter occurring at (16.015, 0.605, and 973.2) vs (16.09, 0.62, and 973.4) measured.

Model Parameter Estimation Method on Multichannel Structural Response from Turbulence Flutter Test

“…The modal parameters can be determined by collecting the structure response. Thehabey [1] used the matrix pencil (MP) method to the dynamic instability analysis of aeroelastic systems. Kiviaho et al [2] performed a study based on the complex exponential method and MP method to identify the modal parameters of the flutter test signal to predict the flutter boundary.…”