Open Space Flammable Gas Cloud Explosion

Unconfined gas cloud explosions have caused great casualty and economic loss. It is very necessary to predict the power of potential explosions and to take effective measures to prevent or lower the damage.The main work and conclusions of present paper are as follows.(1) Three conservation equations on unconfined gas cloud explosions were deduced and reasonably simplized. Based on finite difference technique, a new numerical simulation program on hemispherical gas cloud was worked out by homogeneous energy addition method and artificial viscosity, with which deflagration parameters were computed.(1)The larger the gas cloud radius is, the higher the maximum explosion pressure is. With the rising of gas cloud radius, the explosion pressure increases quickly during energy releasing period, and rapidly attenuates when the flammable gas burns up within gas cloud.(2) The larger the explosion heat is, the higher the maximum explosion pressure is. With the growing of explosion heat, the explosion pressure sharply increases during energy releasing period, and rapidly attenuates after the flame is distinguished within gas cloud.(2) The Liman Problem is normally adopted to check the liability of numerical method. The calculation error was within 9% by comparison with the theoretic solutions of Liman Problem in the following case, the dimensionless calculation length was 2 with high pressure zone 0.8, and the dimensionless stateparameters were p1=2,p2 = 1, p1 = p2 = 1 , u1 = u2 = 0 . Experiment results inLiterature [8] were used to check the adaptability of the numerical model developed here for unconfined gas cloud explosions and the calculation error was within 13%.(3) A testing system consisting of pressure transducers, data-collecting card, computer and electrical-ignition instrument was designed and a flammable gas cloud deflagration experimental system was developed. Based on the orthodoxy experiments, the experiments was conducted on C2H2 -air flame acceleration resulted from hemispherical porous barriers in hemispherical gas cloud. The relations between the explosion overpressure and its influence factors weresummarized.(1) Radius and interspaced ratio of barriers show distinctive effect on explosion overpressure.(2)For single spherical barrier, in case of given gas cloud radius and barrier radius , the explosion overpressure decreases with the increasing of barrier interspaced ratio, and the relation between explosion overpressure, barrier interspaced ratio and distance from explosion center can be expressed by at the range of r/R0 = 1 .2 - 4.0 .(3)For single spherical barrier, in case of given gas cloud radius and barrier interspaced ratio, the explosion overpressure decreases with the rising of barrier radius, and the relation between explosion overpressure, barrier radius anddistance from explosion center can be expressed by the range of r/R0 = 1.2 - 4.0 .(4)When the gas cloud radius and the barrier interspaced ratio are given, the explosion overpressure increases with the growing of barrier number.