大尺寸坑道气体爆炸试验状态控制数值仿真

Numerical simulation on the state control of gas explosion trial in a largescale tunnel

真实管廊尺寸或大尺寸气体爆炸试验是研究城市管廊气体泄漏爆炸事故最直接有效的方法,为使该类试验的设计更加科学有效,通过对坑道甲烷气体泄漏爆炸试验进行等尺寸的数值仿真,探究了坑道内甲烷气体泄漏及静置过程中甲烷分布的时空规律,提出了相关参数,以有效地定量表征三维空间内甲烷气体分布的不均匀程度,并研究了坑道内甲烷气体分布的不均匀程度控制方式,以及其对气体爆炸燃爆参数的影响。

The present paper intends to explore the spatio-temporal regularity of the methane gas leakage in the tunnel and the distribution of the methane concentration rates during the static process by conducting an equal-size numerical simulation of the tunnel methane gas leakage explosion experiment needed.The real pipe gallery size or the large-scale gas explosion experiment can be said to be the most direct and effective research method for testing of the gas leakage and explosion accidents of urban pipe gallery.To study its safety in the gas explosion accidents,a relatively large gas explosion load and dangerous state has to be gained through effective scientific experimental design.To successfully finish the said experiment,it is of absolutely necessary to effectively quantify the unevenness of methane gas concentration distribution in the 3-D space.And,therefore,to study and find the effect of changes in inflation mode and standing time on the methane gas concentration distribution in the tunnel,it is also in turn to study the influence of gas unevenness on gas explosion.Due to the influence of the combustion and explosion parameters,we have found that changing the inflation mode to make the inflation rate more uniformly helps to reduce the unevenness of the methane gas concentration distribution in the tunnel effectively.And,proper choice of the standing time can help to mix the methane gas in the tunnel more evenly and uniformly so as to get rid of the diffusion and stratification of the methaneair mixed gas under the action of gravity under the expansion effect of the methane-air mixed gas,The reason is that,the explosion overpressure of the methane-air mixed gas is inversely related to the uneven degree of the gas concentration distribution for the equivalence ratio of the said mixed gas.Thus,it can be concluded that the degree of unevenness of methane gas in the tunnel can be controlled through controlling the inflation method and the standing time so as to obtain a more idealistic explosion load,which should serve as the basis for controlling and choosing the initial conditions in the design of such experiments.