Abstract: To analyze the explosion characteristics of coal dust, the effects of particle size and concentration of coal on the maximum explosion pressure , explosion index were investigated by using a 20 L explosive ball test device and the Fluent software. The results show that in the experimental environment 293-303 K,when the ignition energy is 10 kJ,with the increase of dust concentration, the maximum explosion pressures of three different clouds of coal dust, particle sizes of which are 26,73 and 115 μm respectively, rise first and drop afterwards , reaching their maxima at 350 g/m³, that at the same dust concentration, the maximum explosion pressure and the explosion index all increase with the decrease of the particle size , that the particle size of 26 μm, concentration of 350 g/m³ coal dust can maintain a relatively stable state during the period of 60-120 ms,and the diffusion reaches a relatively uniform state in around 60 ms ,that after the explosion, the highest temperature in the combustion zone reached 2 060 K, and the unburned area temperature increased from 300 K to 375 K, and that 26 μm dust cloud explosion hazard is rated gradeⅡ,73 and 115μm dust clouds explosion hazards are rated gradeⅠ.

Key words: dust particle size, explosion pressure, ignition delay, numerical simulation, turbulence