Abstract
We developed the burner that was able to form a cylindrical diffusion flame that had a high curvature, and investigated behavior and the extinction characteristics of the flame. The fuel and the oxidizer used the methane and air respectively. The fuel was diluted with helium. The fuel flows from a center axis to surroundings, and air flows from surroundings toward a center axis. The obtained results are summarized as follows. (1) The developed burner can form the flame that has a high curvature of about 2.5mm in the diameter. (2) The airflow velocity greatly changes the radius of the flame than the fuel flow velocity. (3) The flame luminosity increases when the fuel flow velocity is constant and the airflow velocity is increased. However, the flame luminosity decreases when airflow velocity exceeds a certain value. (4) Flame strength strengthens remarkably as the fuel-flow velocity decreases when the Lewis number of fuel-flow is large. (5) The extinction stretch rate increases as the dilution rate of the fuel decreases, and the flame radius at extinction decreases.
