Research On Propagation And Injury Model Of Coal Dust Explosion In Confined Space

Based on gaseous and coal dust explosion theory, propagation law of coal dust explosion in confined space and law of accident injure are investigated systematically though the experimental testing, theoretical analysis and numerical simulation. This thesis provides important theoretical and technological supports for the coal dust explosion emergency decisions, accident investigation and analysis results from the coal dust explosion.Physical contrast experiments at the propagation characteristics of coal dust explosion in the pipeline and tunnel are made using self-designed piping explosion system. Research indicates that the overall trend of coal dust explosion blast wave is increases first and then attenuation, and large-size roadway tunnel decays more slowly than the small-size. Besides, the flame propagation distance in roadway is about twice as much as the raw coal dust concentration zone, and flame transmission distance in the pipe is much larger than the distance of the propagation distance inside the roadway which has size effect, and both do not follow the similitude of the general fluid mechanics. What's more, from the experimental data we obtained that the propagation distance is exponentially related to the variation of coal dust volume. After the blast wave, the blast air (explosion wind) flows along in the direction of the blast wave at a certain speed. The propagation of toxic gas generated by explosion is carried out in stages, that is, the first stage is that the mixture of high concentrations of toxic gas expanded rapidly under the action of the dynamic pressure. The propagation distance of flame and toxic gas are almost equal, and there may be a limit distance in the first phase. When the expansion of toxic gas group stagnate, then enter the second phase of the spread of turbulent diffusion. The result that the propagation distance is exponentially related to the variation of coal dust volume, is obtained by fitting of the experimental data.According to coal dust explosion propagation theory and the overpressure injury 0criterion, set up the accident damage model of explosion blast wave, flame, impact air-flow and toxic gas. After comparing experimental value with theoretical value of the model, we find that the size of blast wave overpressure is proportional to the amount of coal dust explosion, but is inversely proportional to the square root of transmission distance and the sectional area of roadway. Compared with the static model, the dynamic model about the fireball thermal radiation damage of flame spread can be more rational assessment of the consequences of fireball thermal radiation. Furthermore, this damage model is able to calculate the exact solution about injury affected range or area, and ascertain the dead area, deep wounds area and slight injury area ("three areas"). The calculation method of attenuation of blast wave propagation distance under two different states of the coal dust explosion in the weak and strong explosion is also established through theoretical analysis, and this method can calculate the injurie range of different types of blast.The mathematical model of coal dust explosion propagation established according to the continuous phase, combustion, particles of mathematical equations, which can effectively simulate the transtion of explosive burning to explosive detonation. Numerical simulation of coal dust explosion can emulate the development process of coal dust particles scatter, acceleration and deceleration in coal dust explosion and the diffusion process of toxic gas in a certain wind speed. Numerical simulation results show that the conclusion that the decay law of toxic gas concentration is exponentially related to the propagation distance, derived from experimental and theoretical analysis, which conforms to the simulation results.Typical accident of coal dust explosion induced by gas explosion of coal-mine is analysed through appling the accident damage model of explosion blast wave, flame, impact air-flow and toxic gas which established through experiments, theoretical analysis and numerical simulation. Test results indicate that model data is in basic agreements with the actual data measured from the accident, and this model is also featured with a certain reliability, can be applied in hazard analysis of explosion accident.