Unsteady aerodynamic forces for aeroelastic analysis of two-dimensional lifting surfaces

Abstract

The present work is part of an effort for developing a methodology for the aeroelastic analysis of two-dimensional lifting surfaces using an unsteady, Euler-based, CFD tool for the calculation of the aerodynamic operator. The CFD tool solves the flow problem with the finite-volume method applied to an unstructured grid context. The proposed methodology is based on the determination of the aerodynamic operator with the transfer function technique, which is given, in the frequency domain, by the analysis of the system response to an exponentially-shaped pulse in the time domain. The response in the frequency domain is achieved with the Fast Fourier Transform (FFT) technique available in any mathematical manipulation tool, such as Matlab©. Some numerical experiments are performed involving unsteady subsonic and transonic flows around a flat plate and a NACA 0012 airfoil, and the results are presented as curves of generalized aerodynamic forces. The unsteady simulations start from a converged steady state solution obtained by the same CFD tool. Some unsteady validation results are compared with available data in the literature and the initial steps of the methodology are tested. The frequency domain results obtained agree very well with other numerical solutions given in the literature, which validates the present approach for the evaluation of the generalized aerodynamic forces for use in efficient, frequency domain, aeroelastic analyses

Prediction of Transonic Limit-Cycle Oscillations Using an Aeroelastic Harmonic Balance Method

“…These discrepancies are consistent with the results reported in the literature [27][28][29]. Additionally, a convergence study concerning the number of harmonics required to accurately recreate the periodic forces is also carried out and the results are shown in Fig.…”

Aeroelastic behaviour of a wing with over-the-wing mounted UHBR engine

“…For the investigation of the unsteady aerodynamics an impulse motion according to [12,13] is used. A pulse movement is impressed on the profile in the time domain and the resulting coefficients are recorded.…”

Flow past a self-oscillating airfoil with two degrees of freedom: measurements and simulations

“…The classical example is the flutter instability of airfoils, which occurs for systems with two degrees of freedom when the critical flow velocity is surpassed [1]. The consequent large-amplitude oscillations can result in destruction of the elastic part due to low-cycle fatigue [2], with possibly catastrophic consequences. Thus, the importance of theoretical and experimental analysis of the aeroelastic phenomena in these applications cannot be placed in doubt.…”