예혼합 합성가스 충돌 제트 화염에서 화염 진동에 관한 연구 Part II : 진동하는 평면 화염의 특성
A Study on Flame Oscillation in Premixed Syngas(H2/CO) Impingement Jet Flames Part II : Characteristic of Oscillating Lifted Disc Flame
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This work was experimentally conducted in impingement jet configuration with a premixed syngas-air mixture having the volume ratios of 10% and 90% for H2 and CO, by varying Reynolds number(950 to 2550) and equivalence ratio(0.675 to 1.1). The study focused on clarifying the mechanisms on the oscillation generated in lifted noisy disc flame(noisy flame) and the instability driven by flame-vortex interaction mechanism. The results suggest that the flames were formed at fully developed flow beyond potential core region by confirming free jet propagation theory and measuring experimentally velocity profiles between nozzle and plate. These mean that the effect of the flow to the flame could be ignored. Also, the non-reacting flow field presented divergent flow shape, but the reacting flow field showed a “S” shape by high speed camera(1000 fps), video camera(960 fps). The FFT frequencies of flame and vortex were acquired by high speed camera images. The frequency was obtained by analyzing data which measured pressure fluctuation inside and outside of burner. The frequency of cold vortex(Vcd = 140 ~ 180 Hz) was different to natural frequency of burner itself(60 Hz). The frequencies of vortex and pressure perturbation were similar to flame frequency. Thus, the cause of oscillation was not the flow but by flame and the flame-vortex interaction was associated with feedback mechanism as comparison of frequency, pressure perturbation and vortex.
Abstract
This work was experimentally conducted in impingement jet configuration with a premixed syngas-air mixture having the volume ratios of 10% and 90% for H2 and CO, by varying Reynolds number(950 to 2550) and equivalence ratio(0.675 to 1.1). The study focused on clarifying the mechanisms on the oscillation generated in lifted noisy disc flame(noisy flame) and the instability driven by flame-vortex interaction mechanism. The results suggest that the flames were formed at fully developed flow beyond potential core region by confirming free jet propagation theory and measuring experimentally velocity profiles between nozzle and plate. These mean that the effect of the flow to the flame could be ignored. Also, the non-reacting flow field presented divergent flow shape, but the reacting flow field showed a “S” shape by high speed camera(1000 fps), video camera(960 fps). The FFT frequencies of flame and vortex were acquired by high speed camera images. The frequency was obtained by analyzing data which measured pressure fluctuation inside and outside of burner. The frequency of cold vortex(Vcd = 140 ~ 180 Hz) was different to natural frequency of burner itself(60 Hz). The frequencies of vortex and pressure perturbation were similar to flame frequency. Thus, the cause of oscillation was not the flow but by flame and the flame-vortex interaction was associated with feedback mechanism as comparison of frequency, pressure perturbation and vortex.
참고문헌 (20)
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