泡沫铜对密闭管道内合成气爆炸特性影响的实验研究

Experimental study on influences of copper foam on explosive characteristics of syngas in a closed pipe

为研究泡沫铜孔隙密度和H2体积分数对合成气爆炸特性的影响,在封闭的管道中安装了孔隙密度为15、25和40 ppi的泡沫铜,实验分析了当量比为1的合成气-空气在不同H_(2)体积分数时的火焰结构、尖端速度和超压等参数变化规律。实验结果表明:火焰在泡沫铜上游的行为是受“郁金香”火焰形成过程的影响,泡沫铜对其没有影响。但是孔隙密度和H2体积分数的改变不仅会影响“郁金香”火焰的形成时间,还会影响变形“郁金香”火焰的形成。泡沫铜将火焰分割促使其从层流向湍流转化,对爆炸火焰传播起到加速作用。泡沫铜会引起管道内超压和火焰尖端速度的极大提升,且孔隙密度越小,H_(2)体积分数越大,火焰穿过泡沫铜后的最大火焰尖端速度越大,压力上升幅度越大,超压峰值越高。

In order to investigate the effect of the pore density of copper foam and hydrogen volume fractions(φ)on the inair-explosive characteristics of premixed syngas,copper foams with pore densities of 15,25 and 40 ppi were fixed in a closed pipe(100 mm×100 mm×1000 mm)500 mm from the ignition end.Correspondingly,the premixed syngas-air flame propagates in duct without copper foam was compared.The configuration,tip velocity and overpressure,etc.of the flame were observed by igniting the premixed syngas with equivalence ratio of 1 to the air and a wide range of hydrogen volume fractions(from 10% to 90%).Detailed flame evolution process was visualized by a high-speed camera and the overpressure was recorded by pressure transducer.The results indicates that the copper foam has a significant impact on flame propagation and overpressure-time history.Before the flame reaching the copper foam,its configuration and tip velocity,as well as the overpressure,are only determined by the fuel component,but not the foam,during its formation process to a tulip shape.The pore density and φ affect not only the formation time of tulip flame,but also the appearance of distorted tulip flame.The copper foam could lead to the segmentation of flame front and transform the flame front from laminar to turbulence,resulting in the flame acceleration.This phenomenon becomes more evident with the decreasing of pore density.The presence of copper foam can increase the flame tip speed and overpressure significantly.For the case with a smaller pore density,both the maximum flame tip speed,growth of overpressure and maximum overpressure of premixed syngas-air increase with the.