Abstract The efficiency of modern methods of experimental hydromechanics for determining local and global instability modes in turbulent flows is demonstrated. The particle image velocimetry technique and the method of dynamic mode decomposition for the analysis of instantaneous flow velocity fields were used to study non-swirling and strongly swirling jet flows of rich propane-air mixture issuing into atmospheric air and burning as a suspended flame. Modes induced by the Kelvin-Helmholtz instability and vortex core precession are determined.@en