当量比和初压对二甲醚-空气爆炸特性的影响研究  

Effect of the equivalence ratio and the initial pressure on the particular features of the dimethyl ether-air explosion

作　　者：丁以斌 高伟 DING Yi-bin;GAO Wei(Anhui Research Institute of Emergency Management,Hefei 230061,China;School of Chemical Engineering,Dalian University of Technology,Dalian 116024,Liaoning,China)

机构地区：[1]安徽省应急管理科学研究院,合肥230061 [2]大连理工大学化工学院,辽宁大连116024

出　　处：《安全与环境学报》2021年第5期2076-2080,共5页Journal of Safety and Environment

摘　　要：为探究二甲醚-空气爆炸特性,采用高速光学纹影技术和高频动态压力测量技术获取当量比和初压对二甲醚-空气火焰形态和爆炸超压峰值的影响规律。采用刘易斯数、热膨胀比和火焰厚度理论分析了火焰形态,采用燃烧热损失理论分析了爆炸超压峰值。结果表明,高速光学纹影技术和高频动态压力测量技术可清晰、准确地获取二甲醚爆炸火焰形态和爆炸超压峰值。在热扩散不稳定和流体动力学不稳定相互作用下,火焰形态大致可以划分为3类:光滑火焰、裂痕火焰和胞状火焰。当量比Φ=0.8和Φ=1.0时,刘易斯数大于1.0,热扩散不稳定迫使球形膨胀火焰趋于稳定,不同初压下火焰形态相对光滑或表面出现少许裂痕,未观测到胞状火焰;当量比Φ=1.5时,刘易斯数接近于1.0,球形膨胀火焰仅受流体动力学不稳定的影响,初压达到200 kPa时形成胞状火焰。随初压增加,刘易斯数几乎恒定,热膨胀比缓慢增加,火焰厚度迅速减小,即热扩散不稳定对球形膨胀火焰的影响效应不变,流体动力学不稳定对球形膨胀火焰的失稳效应逐渐增强。另外,对于不同当量比和初压,绝热工况二甲醚爆炸超压峰值均高于试验工况。随初压增加,绝热工况和试验工况二甲醚爆炸超压峰值均线性增加,不同当量比下燃烧热损失单调增加。The present paper is aimed at exploring and exposing the effects of the equivalence ratio and the initial pressure on the special flame features and the maximum explosion overpressure of dimethyl ether-air mixture via the high-speed schlieren technology and that of the high-frequency dynamic pressure measurement so as to predict or assess the likeliness of the DME-air explosion.For such a research goal,we have chosen the Lewis number,the thermal expansion ratio and the flame thickness to analyze the DME-air flame morphology,with the combustion heat loss taken to analyze the maximum explosion overpressure.The above research results may tend to indicate that it would be possible for the flame morphology and the maximum explosion overpressure of D ME-air mixture to be gained accurately via the high-speed schlieren technology and that of the high-frequency dynamic pressure measurement.For instance,the flame morphology of DME-air mixture can be properly divided into the following sections,say,the smooth flame,the crack flame and the cellular flame under the thermal-diffusive and hydrodynamic instability conditions.For instance,when the equivalence ratio stands asΦ=0.8 andΦ=1.0,the spherically expanding flame may tend to get stable under the condition of the thermal-diffusive instability with the Lewis number being greater than 1.However,if the smooth flame and the crack flame can only be observed at the various initial pressures,though the cellular flame would not be formed on the condition whereinΦ=0.8 andΦ=1.0.For instance,when the equivalence ratio isΦ=1.5,the spherically expanding flame can only be affected by the hydrodynamic instability.And,then,when the cellular flame is turning up to the initial pressure of 200 kPa,with the increase of the initial pressure,the Lewis number may tend to become almost constant,and the thermal expansion ratio would then in turn grow up slowly,with the flame thickness or strength getting down promptly.Or,in other words,the effects of the thermo-diffusive instability on the sph

关 键 词：安全工程 二甲醚 火焰形态 爆炸超压峰值 燃烧热损失 

分 类 号：X932[环境科学与工程—安全科学]