摘要
工业尾气回收网结构复杂,存在许多变径结构,回收气体大多燃易爆,因此有发生燃爆事故的风险。为探究变径结构对可燃气云燃爆过程的影响,在管长为0.5 m变截面管道内,采用预混燃烧模型和Zimont湍流燃烧模型,对可燃预混气体燃爆特性开展了大涡模拟(LES)研究。结果表明:在0.5 m管长的通径管道内,管道截面越小,管壁对火焰的约束作用越大,壁面反射增强,管道壁面形成的湍流加速壁面附近的火焰传播速度,使得Tulip火焰出现越早,达到最大火焰传播速度的位置距点火端越近;管道截面越小,火焰厚度越大。不同管道结构下Tulip火焰结构不同,在突缩和连续突缩管道中Tulip火焰产生变形,火焰锋面不再光滑;变截面结构对火焰传播有激励作用,管道内截面变化后涡团的产生和演化加速了火焰传播,突缩管道结构对火焰传播有明显的加速作用,因此尾气回收管网设计需尽量减少突缩管道结构或在突缩管道结构位置增加阻火装置。
The present paper is inclined to make an exploration of the impact of the variable diameter structure on the combustion process of the flammable gas clouds through a large eddy simulation mode(LES)for the premixed combustion model and the Zimont turbulent combustion model so as to disclose and clarify the explosive features of the premixed combustible gas in the variable cross-section pipe with the length of 0.5 m.As is well-known,the recovery structure of the industrial exhaust gas is both complex and complicated with a great potential risk of explosion.As it has been found,the smaller the pipe cross-section,the sooner the tulip flame would appear,and,in turn,the nearer and closer the flame will be approaching to the ignition end.For example,in the flame propagation process,the transition and transmission from the laminar flow to the turbulence tends to be happening in a mutually accompanying manner,for the reason that,with the reduction of the pipe cross-section,it would be highly possible for the interior surface of the pipe to become turbulent.And,accompanyingly,the wall would produce a great restraining effect on the flame,which is likely to enhance the wall reflection.At the same time,the flame propagation near the wall surface can be accelerated by the turbulence of the pipe wall.The thickness or the strength of the flame is actually related inversely to the cross-section of the pipe just near the pipe in a distance of 0.5 m.And,when the cross-section of the pipe decreases,the thickness or the strength of the flame would increase to lead the tulip flame to a structure various under the action of the different pipe structures.What is more,in the constrained continuously contracted pipe,the tulip flame can be deformed with the flame frontage turning to be no longer smooth.Thus,the variable cross-section structure would bring about a kind of incentive effect on the flame propagation.And,consequently,in the variable cross-section pipeline,there may appear a vortex as a result of the cross-section change,so as to deform its further development and evolution and cause the flame front to wrinkle the tulip flame,which should accelerate the flame propagation due to the generation and evolution of the vortex.Therefore,as compared with the continuous contraction of the pipe,the contracted pipe structure is likely to result in a significant acceleration effect on the flame propagation.And,that is why in the design of the network of the exhaust gas recovery pipe,the structure of the said pipe should be minimized or the fire arresting device should be added at the position of the constricted pipe.
作者
周宁
戴瑶瑶
陈兵
李雪
赵会军
黄维秋
ZHOU Ning;DAI Yao-yao;CHEN Bing;LI Xue;ZHAO Hui-jun;HUANG Wei-qiu(School of Petroleum Engineering,Changzhou University,Changzhou 213164,Jiangsu,China;China Academy of Safety Science and Technology,Beijing 100012,China)
出处
《安全与环境学报》
CAS
CSCD
北大核心
2021年第2期599-606,共8页
Journal of Safety and Environment
关键词
安全工程
变截面管道结构
可燃气云燃爆规律
Tulip火焰
火焰速度
湍流燃烧
safety engineering
variable section pipe structure
explosion law of combustible gas cloud
Tulip flame
flame velocity
turbulent combustion
