This paper describes the coupled flow and flame dynamics during blowoff and reattachment events in a combustor consisting of a linear array of five interacting nozzles using 10 kHz repetition-rate OH planar laser-induced fluorescence and stereoscopic particle image velocimetry (S-PIV). Steady operating conditions were studied at which the three central flames randomly blew-off and subsequently reattached to the bluff-bodies. Transition of the flame from one nozzle was rapidly followed by transition of the other nozzles, indicating cross-nozzle coupling. Blow-off transitions were preferentially initiated in one of the off-center nozzles, with the transition of subsequent nozzles occurring in a random order. Similarly, the center nozzle tended to be the last nozzle to reattach. The blow-off process of any individual nozzle was similar to that for a single bluff-body stabilized flame, though with cross-flame interactions providing additional means of restabilizing a partially extinguished flame. Subsequent to blowoff of the first nozzle, the other nozzles underwent similar blow-off processes. Flame reattachment was initiated by entrainment of a burning pocket into a recirculation zone, followed by transport to the bluff-body; the other nozzles subsequently underwent similar reattachment processes. Several forms of cross-nozzle interaction that can promote or prevent transition are identified. Furthermore, the velocity measurements indicated that blowoff or reattachment of the first nozzle during a multinozzle transition causes significant changes to the flow fields of the other nozzles. It is proposed that a single-nozzle transition redistributes the flow to the other nozzles in a manner that promotes their transition.
Blowoff and Reattachment Dynamics of a Linear Multinozzle Combustor
Manuscript received June 28, 2018; final manuscript received July 12, 2018; published online September 14, 2018. Editor: Jerzy T. Sawicki.
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Kwong, W. Y., and Steinberg, A. M. (September 14, 2018). "Blowoff and Reattachment Dynamics of a Linear Multinozzle Combustor." ASME. J. Eng. Gas Turbines Power. January 2019; 141(1): 011015. https://doi.org/10.1115/1.4041070
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