波纹管道阻火器内火焰传播的实验与数值模拟研究

发布时间：2018-02-09 16:18

本文关键词： 波纹阻火器淬熄 “郁金香”火焰爆燃火焰速度爆炸压力　出处：《爆炸与冲击》2017年02期 　论文类型：期刊论文

【摘要】：对乙烯-空气预混火焰在波纹管道阻火器中的传播与淬熄过程进行了实验和数值模拟研究,实验结果显示:当乙烯接近当量浓度时,预混气体爆炸压力变化过程可分为4个阶段,等压燃烧阶段、缓慢上升阶段、快速上升阶段和压力振荡阶段;在爆炸过程中,由于反射压力波和火焰相互作用的影响,超压值出现多次振荡,压力振荡阶段一般可以持续数十毫秒;乙烯-空气火焰传播速度随管径增加、阻火单元波纹高度减小呈递增趋势,而且随着阻火单元厚度的增加,阻火器的阻火能力明显提高,可以更有效地使火焰淬熄。数值模拟结果显示:在管道封闭端点火后,火焰面呈半球形并以层流扩散的方式向四周传播;当火焰传播到管道壁面时,在管道壁面的约束作用下,火焰面发生变形,壁面附近的火焰逐渐超过了管道轴线附近的火焰,最后形成了"郁金香"状的火焰结构;当爆燃火焰经过阻火单元时,高温已燃气体被其吸收大量热量,同时在反应区产生的稀疏波作用下,气体温度逐渐降低、化学反应速率迅速减小,最终导致火焰被熄灭。通过模拟计算结果可以看出,在整个爆炸过程中,火焰传播速度与爆炸压力波动均较为明显。并提出了孔隙率和阻火单元厚度对火焰传播的影响机制。基于传热学理论模型,并结合实验数据,得出了爆燃火焰速度与爆炸压力之间的关系,为工业装置阻火器的设计和选型提供更为准确的参考依据。
[Abstract]:The propagation and quenching process of ethylene-air premixed flame in bellows are studied experimentally and numerically. The experimental results show that when ethylene is close to equivalent concentration, The process of pressure variation of premixed gas explosion can be divided into four stages: isobaric combustion stage, slow rising stage, rapid rising stage and pressure oscillation stage. The pressure oscillation stage usually lasts for tens of milliseconds, and the propagation velocity of ethylene-air flame increases with the pipe diameter, and the corrugation height of the flame arrester unit decreases with the increase of the thickness of the flame arrester unit. The flame quench can be effectively quenched by the fire arrester. The numerical simulation results show that the flame surface is hemispherical and propagated in the form of laminar diffusion after igniting at the closed end of the pipe. When the flame propagates to the pipe wall, under the restraint of the pipe wall, the flame surface is deformed, the flame near the wall gradually exceeds the flame near the pipeline axis, and finally the "tulip" flame structure is formed. When the deflagration flame passes through the flame arrester unit, the high temperature gas body is absorbed by it, and the gas temperature decreases gradually and the chemical reaction rate decreases rapidly under the action of sparse wave generated in the reaction zone. And eventually the flame was extinguished. From the results of the simulation, we can see that during the whole explosion, The flame propagation velocity and explosion pressure fluctuate obviously. The influence mechanism of porosity and the thickness of fire resistance unit on flame propagation is proposed. Based on the theoretical model of heat transfer, and combined with the experimental data, The relationship between deflagration flame velocity and explosion pressure is obtained, which provides a more accurate reference basis for the design and selection of industrial igniter.
【作者单位】：大连理工大学化工机械学院;沈阳特种设备检测研究院;
【基金】：国家质检总局科技计划项目(2011QK083) 沈阳市科技计划项目(F14-048-2-00)
【分类号】：X932

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