Multi-scale proper orthogonal decomposition analysis of instabilities in swirled and stratified flames

This study examines the flow field dynamics of bluff-body stabilized swirling and non-swirling flames produced from Cambridge/Sandia Stratified Swirl Burner. burner has been used in previous studies as a benchmark for high-resolution scalar velocity measurements validating numerical models. The was designed to create reacting conditions that are representative turbulent flows modern combustion systems, including sufficiently high turbulence levels, operate under both premixed stratified conditions. High-speed stereoscopic particle image velocimetry acquire time-resolved data series methane/air at We employ multi-scale proper orthogonal decomposition (mPOD) identify main patterns isolate coherent structures linked various instabilities. results show most energetic consistent with Bénard–von Kármán (BVK) instability due presence Kelvin–Helmholtz (KH) caused by shear layer between inner outer flow. In cases, BVK is suppressed combustion, except case. Moreover, does not affect KH because coincide flame position.