Study on Aeroelastic Characteristics of a Cropped Delta Wing Before and After Vortex Breakdown

• 1、National Key Laboratory of Aerodynamic Design and Research, Northwestern Polytechnical University

Abstract：Aeroelastic analysis at high angle of attack is an attractive and complicated research in modern aircraft design. By using N-S equations and coupling with structural motion equations, an aeroelastic analysis of a 70 degree cropped delta wing before and after vortex breakdown in time-domain is carried out in state-space. It is shown that the unsteady fluctuation characteristics of flow become highly obvious after the vortex breakdown, and have a significant impact on the aeroelastic characteristics of the wing. Before the vortex breakdown, the aeroelastic instability presents only a simple flutter. However, after the vortex breakdown, aeroelastic problem is likely neither a simple flutter, nor a simple buffet induced by the external excitation loads on the wing, but a complex problem including flutter and buffet. As the angle of attack increases, the vortex breakdown location moves forward, and the external excitation loads due to the vortex breakdown rise, and the influence of buffet enhances, and the aeroelastic characteristics present a more obvious phenomena involving flutter and buffet. Besides, from the analysis of the power spectra density (PSD), it is also found that the fluctuating loads on the wing rise and the frequency of the peak on the PSD decreases as the angle of attack increases.

Keywords： aeroelasticity Navier-Stokes equations delta wing high angle of attack separation vortex flutter buffet