Analysis of transonic buffet using dynamic mode decomposition

Abstract The buffet flow field around supercritical airfoils is dominated by self-sustained shock wave oscillations on the suction side of wing. Theories assume that this unsteadiness driven a feedback loop disturbances in downstream whose upstream propagating part generated acoustic waves. High-speed particle-image velocimetry measurements are performed to investigate transonic over DRA 2303 airfoil. freestream Mach number $$M_{\infty } = 0.73$$ M ? = 0.73 , angle attack $$\alpha 3.5^{\circ }$$ ? 3 . 5 ? and chord-based Reynolds $${\mathrm{Re}}_{c} 1.9\times 10^6$$ Re c 1.9 × 10 6 . obtained velocity fields processed sparsity-promoting dynamic mode decomposition identify dominant features contributing strongest field. Two pronounced modes found which confirm presence two main proposed loop. One related oscillation frequency its shape includes movement coupled pulsation recirculation region wave. other represents form corresponds waves these traveling In study, post-processing, i.e., DMD, highlighted substantiate existence vortex mode. It via Lamb vector excites oscillations. measurement data based DMD results numerical findings, good agreement with suggested Lee. Graphic abstract