Investigation On Detonation Characteristics Of Liquid Fuel-Air Mixtures, Explosion Suppression And Venting

In this thesis, the experimental investigations, theoretical analysis and numerical simulations are carried out to study the detonation characteristics of fuel-air mixtures, explosion suppressions and venting. The relevant parameters of heterogeneous detonations, explosion suppression and venting are obtained experimentally, and the mechanism is revealed. Some ideas or approaches are put forward to industry explosion hazards mitigation and control.Critical initiation energy is measured by up and down method and on soot foil in vertical detonation tube. Results demonstrate that the relationship of critical initiation energy and equivalence ratio shows an "U" shape curve, the cell size is also. The critical point of the sensitivity of the fuel vapor is slightly larger than 1. The comparison of detonation characteristics among these fuels indicates that detonation of fuel-air mixtures in low fuel vapor pressure is similar to the gaseous detonation. With the enhancing of ignition energy it will lead to a more complex cellular structure. And the ratio of its length to width is less than the gaseous fuel. These experimental results help us deeply understanding the detonation nature of hydrocarbon fuel-air mixtures.In detonation tube, explosions are more or less suppressed by passive or active water mists and inert dust cloud, and the characteristics of corresponding flow-field and relevant parameters are obtained. For inert suppressant (water mists or inert dust), only if the concentration is larger than a critical value, explosion can be suppressed completely, otherwise, it may become strong again after passing through the suppressant flow. Also, the results indicate that contained NaHCO₃ are more efficient.With a cylindrical vented vessel connected to a duct, the experiments on the venting to air under different venting conditions were performed and the pressure-time profiles of the venting flow field were obtained. In addition, the influence factors and characteristics of the intensity of the secondary explosion were discussed in detail according to the experimental data. When the other venting conditions were fixed, the probability of the secondary explosion in low equivalent ratio(less than 1.0) of fuel-air mixtures was lower than the high (more than 1.0).Based on water dispersion experimental data, the two-fluid model is used to simulate the explosive dispersion process of water. Computation results are in good agreement with the experiments. The law of the dispersion process is revealed, and it indicates that the parameters of water dispersion can be well predicted by this model.