A214 Enhancement of Jet Diffusion Flame Blowout Limits toy Doublet Flows and Counter-flowing Swirl(Laminar flame-3)

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Two novel methods, namely doublet flows and counter-flowing swirl, were developed to attain enhancement of jet diffusion flame blowout limits. Doublet flows were formed in a concentric annulus, in which fuel was ejected from a nozzle and air was sucked into an outer cylinder encompassing the nozzle. Counter-flowing swirl was generated in the same annulus, in which air was blown tangentially from a tube connected to the cylinder to combine with the suction flow. Results showed that both methods could extend the limits and lower flame lift-off heights. Doublet flows caused frequent flame reattachment while counter-flowing swirl anchored the flame base at certain positions downstream. An equation based on recirculation vortices with self-similarity comparable to turbulent large-scale structure was developed to predict lift-off heights of the swirling flame. The agreement between prediction by the equation and data of experiments provided strong evidence that recirculation vortices dominated turbulent swirling flame stabilization.
一般社団法人日本機械学会の論文
2000-10-01