Comparison of lean blowout behavior of a swirling spray combustor with prefilming and non-prefilming airblast atomizers

In the design of modern high-performance aircraft engine combustors, the lean blowout (LBO) limit is a critical parameter that requires significant attention due to its direct impact on the safety and stability of flight operations. To examine the effects of prefilming (S1) and non-prefilming (S2) atomization on flame features and LBO characteristics, swirling spray flames in a realistic combustor were studied using high-speed optical diagnostic techniques under conditions near LBO. The results indicate that, under the combined influence of atomization performance and swirling flow field structure, S1 flames exhibit a wider LBO limit compared to S2 flames. The S1 flames experience the stages of extinction, re-ignition, and recovery, respectively, while S2 flames gradually extinguish as LBO approaches. Time-averaged images show that the S1 strategy results in a dome-attached flame, whereas S2 leads to a large-scale lifted flame near LBO. Besides, a blowout precursor detection method based on the continuous wavelet transform was proposed. The proposed method can successfully identify the blowout precursor event of weak swirling flames and advance the warning time for LBO by ∼ 60 %. These findings hold significant practical implications for industrial gas turbine and aero-engine combustors.