旋回噴流燃焼器を用いた強乱流予混合火炎の研究:第2報, 静電探針を用いた火炎の微細構造の検討

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To examine flame structure in turbulent flow, we have established highly tubulent flames of a propane-air mixture in a cyclone-jet combustor, and have measured ion current by an electrostatic probe. Based on the measured flow field by a hot wire anemometer, we have obtained turbulence characteristics in the non-reacting flow, and have plotted them on the Peter's phase-diagram to classify the micro-structure of turbulent flames. From the ion current characteristics and tomographic images of flames, we have discussed the flame structure and turbulence. Results show that, as the exit velocity is relatively low, a wrinkled laminar flame is formed. As the exit velocity is further increased, the flame wrinkling is intensified to increase the fluctuation in wave of ion current. When the velocity exceeds 30m/s, the PDF of ion current is no longer that of a wrinkled laminar flame, which shows that, with turbulence, one continuous flame sheet cannot be sustained, and the destruction of laminar flame structure occurs, in which small reacting eddies in an intermediate stage of combustion are embedded. It appears that the flame structure changes from the wrinkled laminar flame to those with distribution reaction zone.
2000-02-25