ブラフボデーを用いた高速水素拡散燃焼における保炎特性の計測:第2報, 燃料噴射による循環流構造の変化と渦放出

概要

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A fiber Laser Doppler Velocimeter(LDV)was used to measure a flow field behind a bluff body at high fuel flow rate condition which was considered to be close to the real operating circumstances in reacting flow. These results were compared to that of low fuel flow rate condition in smooth combustion in order to understand the reason of the onset of rough combustion characterised by flame stretch, noise generation and oscillating combustion. It was found that as the fuel flow rate increased, the reverse flow regions started to show very complex shapes because of the fuel jet penetration. At the end, the recirculation zones combined surrounding the jet. This recirculation zone combination hindered the growth of the recirculation zone itself. Therefore, the air entrainment flow rate into the flame holding regions was not proportional to the increase of bulk air velocity and fuel flow rate. Oscillating frequency was observed in velocity power spectrum at high fule flow rate. The very sharp peak at high frequency was due to the vortex shedding. The main reason of rough combustion at high fuel flow rate were found to be the lack of air entrainment caused by the combination of the recirculation zones together with the vortex shedding behind the bluff body.
社団法人日本機械学会の論文
2000-01-25