Nonlinear Response of Vortex Breakdown over a Pitching Delta Wing

Abstract

A e ow visualization study was carried out to investigate the response of breakdown location to small amplitude pitching oscillations of a delta wing. At moderate angles of attack, left and right breakdown locations are inphase and locked to the pitching frequency. At large angles of attack, low-frequency antisymmetric modes and the symmetric mode at the pitching frequency are observed simultaneously. The existence of multiple frequencies in the spectra and other features suggest that vortex breakdown behaves like a nonlinear self-excited oscillator.