| This research was performed to study characteristics of wheat dust flame propagation with a 5 x 5 x 214.1 cm 3 square tube. Dust particle size used is a diameter of 106 μ m–300 μm and as a supplementary, the dust particle size of 300 μm–325 μm was used.; The dust particles were fed from the top of the tube and a flame was ignited at the bottom of the tube by an electric coil. Flame speeds were measured with series of photographs taken by a video camera and the expanded gas velocities were determined by measuring dynamic pressure with a pressure transducer. The peak flame speeds of small particles and large particles are 532 cm/sec and 373 cm/sec, respectively. The burning velocities vary from 3 cm/sec to 7.5 cm/sec depending on dust concentration. The flame thickness was determined by graphical analysis. However, no distinct relation between the flame thickness and dust concentration was found. The rich flammability limit of wheat dust of the smaller dust is estimated as 790 g/m3. However, since it is believed that rich limit of dust combustion is controlled by heat transfer not by the volume replacement of oxidant by fuel and heat transfer and/or heat loss is dependent upon experimental setups, the value of 790 g/m3 may also depend upon the experimental setups. |
