507 温度勾配のある流れ場における微粒子粉の発火

概要

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An experimental study has been conducted to explore the mechanisms of propagation of combustion zone in dust clouds with taking into account of ignition of powder in preheat zone. A vertical duct having 610 mm height, 65 x 65 mm cross section is used to examine behavior of propagation of combustion zone and ignition processes during the propagation [apparatus I]. Furthermore, to establish temperature gradient in flow a plate heated by an external burner is placed above a 30 mm inner diameter nozzle with a powder issuing system [apparatus II]. Powders of tantalum, zirconium, lycopodium and PMMA (polymethylmethacrylate) are used. Aspects of the combustion zone propagating upwards in the duct are examined by using a high-speed video camera and a PIV (Particle Image Velocimetry) system. The results show that the combustion zone which consists of individual burning particles propagates in the same direction (upwards) to the movement of these particles. Ignition behavior of unburned particles in front of the combustion zone is examined based on the experimental results using the PIV system. Since an unburned particle takes some time to be ignited during the propagation, a residence time that the particle remains in the preheat zone (temperature gradient in flow) is needed to propagate the burning zone continuously.
社団法人日本機械学会の論文
2000-09-08