Large-scale coherent structures resulting from hydrodynamic instabilities can interact with
turbulent swirl flames and lead to combustion instabilities. The present work investigates the
impact of density stratification and azimuthal velocity on the growth of coherent structures in
a convectively unstable swirl flame. Flame structure and flow field are measured by
simultaneous hydroxyl planar laser-induced fluorescence and stereoscopic particle image
velocimetry (S-PIV) at a repetition rate of 10 kHz and are analyzed by using the spectral …