Formation and flame-induced suppression of the precessing vortex core in a swirl combustor: Experiments and linear stability analysis

摘要: Abstract The precessing vortex core (PVC) is a coherent flow structure that often encountered in swirling flows gas turbine (GT) combustors. In some swirl combustors, it has been observed PVC present under non-reacting conditions but disappears the corresponding reacting cases. Since numerous studies have shown strong effects on flame stabilization, desirable to understand formation and suppression of PVCs GT work experimentally field model combustor at atmospheric pressure. Whereas all detached M-shaped flames exhibit PVC, suppressed for attached V-shaped flames. A local linear stability analysis then applied measured time-averaged velocity density fields. For cases where appeared experiment, shows global hydrodynamic instability manifests single-helical mode with its wavemaker located inlet. frequency excellent agreement oscillation growth rate approximately zero, indicating marginally stable limit-cycle. V-flame without radial density/temperature gradients are inlet, which suppress instability. interplay between further investigated by considering bi-stable case intermittent transitions V- M-flame. transients via simultaneous highspeed PIV OH-PLIF. experiments reveal sequence events wherein forms prior transition shape. results demonstrate essential role thereby importance design combustor.