掺氢比例对金属丝网阻抑掺氢甲烷燃烧火焰传播的影响

Effect of hydrogen ratio on inhibition property of wire mesh to propagation of the flame by methane premixed with hydrogen

为进一步揭示金属丝网阻抑掺氢甲烷燃烧火焰传播特征的规律,通过实验研究了掺氢比例对不同孔隙密度金属丝网阻火过程的影响。结果表明:随着掺氢比例的增加,金属丝网的阻火难度加大,金属丝网的阻火效果可由成功转为失败,对火焰传播的影响作用可能从抑制转变为促进;当金属丝网阻火失败时,金属丝网会引起火焰褶皱并导致火焰加速,但郁金香形火焰的首现时间有所延迟;随着掺氢比例的增大,火焰穿过金属丝网后的加速现象更为明显;提高金属丝网孔隙密度可提高金属丝网对掺氢甲烷预混火焰的阻火能力,孔隙密度越大,阻火能力越强;60 mpi以上金属丝网能够有效淬熄掺氢甲烷预混火焰。

In order to further reveal the characteristic of metal mesh to inhibit the flame propagation of hydrogen-methane premixed mixture,hydrogen and methane mixed gas with hydrogen mixing ratio of 0%,10%,20%and 30%were selected to conduct the experimental investigation of the effect of hydrogen mixing ratio inhibiting the fire processing through wire mesh with varied size in an explosion pipeline with an inner diameter of 60 mm and a total visible length of 1024 mm.Firstly,the flame propagation process was recorded by a high-speed camera,and the effect of hydrogen mixing ratio on fire resistance of wire mesh with different mesh numbers and the change of flame morphology were analyzed.Secondly,the average velocity of flame front movement was calculated according to the interval of 50 mm,and the flame propagation velocity within the visible area of the pipeline was analyzed.The interaction law between the metal wire mesh and the flame was mainly characterized by the flame propagation velocity on both sides of the metal wire mesh.The results show that with the increase of hydrogen content,the difficulty of flame retardancy of metal wire mesh increases,and the flame retardancy effect of metal wire mesh can transition from success to failure,and the impact on flame propagation may shift from inhibition to promotion.When the wire mesh fails to resist the fire,the wire mesh will cause the flame to fold and cause the flame to accelerate,but the first appearance of the tulip flame is delayed.With the increase of hydrogen mixing ratio,the acceleration phenomenon of flame passing through the wire mesh is more obvious.Increasing the mesh number of wire mesh can improve the fire resistance of wire mesh to hydrogen-methane premixed flame.The larger the mesh number,the stronger the fire resistance.More than 60 mesh wire mesh can effectively quench hydrogen and methane premixed flame.