Open Space Flammable Gas Cloud Explosion

Due to the great loss of the national economy caused by the vapor cloud explosion, the prediction of the power generated by the potential explosion and the effective and efficient precautions for preventing or lowering the damage has become the main focus of scientific researchers of different countries.A lot of experiments are conducted with a slab or several slabs put in the explosion field. Then the paper discusses the influence of the four factors on the vapor cloud explosion pressure, which are the radius of the hemisphere-shaped vapor cloud , the distance between the explosion center point and the slab, the horizontal and vertical coordinates on the slab.The relation between the pressure on the slab put in only one direction, which is generated by the explosion of the initially quiescent hemisphere-shaped vapor cloud filled with the homogeneous and stoichiometric acetylene-air mixture, and the four factors described above is formulated by Minimum Quadratic Variance Regression after the analysis of the experiment data by the cubic spline numerical insertion method, the equation for the relation is as follows:By comparison with the related experimentalpressure data we get the errors of the values calculated by the above equation: the relative errors of 50% of the data for check are lower than 10%; the relative errors of 87.5% of the data for check are lower than 20%; the relative errors of 96.9% of the data for check are lower than 30%). But it needs further check by large-scale cloud explosion experiments.This paper also discusses the influence of the number of slabs and the location of each slab on the explosion strength. From the experiments we get: theextent of the confinement in the outer space can influence the power of the vapor cloud explosion a lot.This paper also discusses the influence of the fraises in the cloud on the explosion strength. From the analysis of the experiment data we can get: there is no remarkable difference between the pressures got by the experiments with yarn-net inside the hemisphere-shaped vapor cloud and those by the experiments with no obstacles in the cloud; the ratios of the pressures got by the experiments with 12 bricks inside the hemisphere-shaped vapor cloud to those by the experiments with no obstacles in the cloud correspondingly are from 1.7 to 6.The maximum pressure field formed by the explosion of a spherical vapor cloud having no obstacles in the outer space can be calculated by the simplified one-dimension spherical mass and momentum conservation equations. Based on this field, the pressure distributing on the slab can be computed with reference to the pressure change of the shock when confronted by a rigid obstacle. By analysis of the theory we get:㏕he rule of the maximum pressure field formed by the explosion of a spherical vapor cloud having no obstacles in the outer space is as follows: the pressure in the deflagration field is inversely proportional to the distance between the explosion central point and the dot for calculation.When the vapor cloud burns, the flame are accelerating for a distance. So the pressure got by a large cloud must be bigger than a small cloud. is not very big, the maximum pressure is formed as soon as the flame reaches the verge of the flammable cloud; the maximum pressure of the field is on the verge .The deflagration of the gas with a low burning rate and little reactivity an not generate very high pressures.From the theory about the reflection of the air shock we get: the ratio of the reflection pressure to the incidence pressure of a week shock is 1+cos is the incidence angle).By comparison with the related experiment data, the errors of theoretical results are calculated and described as follows: the relative errors of 40% of the data for check are lower than 10%; the relative errors of 70% of the data for check are lower than 20%; the relative errors of 85% of the data for check are lower than 30%.