置障条件下含氢瓦斯爆炸特性试验

Experimental study on the special explosion features of the gas with highly hydrogen content at presence of obstacles

为了获得置障条件下含氢瓦斯爆炸特性,通过试验研究了50 mm×50 mm×250 mm透明管道内连续障碍物条件下氢气体积分数对瓦斯爆炸火焰锋面位置、火焰传播速度、超压及最大超压上升速率的影响规律。结果表明,与氢气体积分数为0时相比,当氢气体积分数分别为1. 5%、3. 5%和6. 5%时,火焰锋面到达出口所用时间分别缩短了3. 3 ms、6. 7 ms和8. 3 ms,最大超压分别增大了10. 5%、62. 8%和109. 2%,最大超压到达时间分别缩短了18. 7%、31. 3%和41. 3%,最大超压上升速率大致呈线性增长趋势。此外,当氢气体积分数增加时,其爆炸超压主要频率对应的分量随之增大,爆炸产生超压振荡的周期性增强,其频率主要分布于200～400 Hz,这种高频超压振荡现象可能与含氢瓦斯爆炸产生较大水蒸气分压进而引起的燃烧诱导快速相变有关。

The paper is to engage itself in conducting an experimental study of the effects of different hydrogen contents at the front flame position.Such a situation comes about due to the flame propagating speed,the overpressure and maximally rising rate of the gas explosion overpressure in a transparent pipe at presence of the continuous obstacles so as to identify and determine the explosion special features of the hydrogen-added gas.In the above said experiment,it is necessary to observe and determine the special features of the explosion process at the pressure of the likely explosion risk of the hydrogen/methane/air mixture under the conditions with the different hydrogen contents being in existence through a high-speed camera and pressure sensors.Theresults of our experiments show that,as compared with the zero hydrogen content,when the hydrogen contents were to be at1.5%,3.5%and 6.5%,the flame front lasting time in the pipe can be shortened by 3.3 ms,6.7 ms and 8.3 ms,respectively.And,in contrast,the maximum overpressure can increase by 10.5%,62.8%and 109.2%,respectively,whereas the time for the greatest overpressure arrival can be cut off by18.7%,31.3%and 41.3%,respectively.Thus,it can be found that the maximum increasing rate of the overpressure also tends to appear in an approximately linear increasing trend.This may imply that,in case the gas contains a small amount of hydrogen,it would be possible for the maximally limited overpressure time to arrive can be significantly reduced with the considerable increase of the explosion power.More exactly speaking,at presence of hydrogen,the continuous obstacles can promote the acceleration of the gas explosion flame.And,what is more,with the increase of hydrogen content,it would be possible for the combustion rate and the flame temperature to get higher.Thus,it can be deduced that the coupling process of the flame and turbulence intensification may turn to be in a position to accelerate the process of the flame front propagation.In addition,with the increase of hydrogen content,the overpressure frequencies of the main corresponding components can get increased,too.When the explosion overpressure periodicity is stronger,its frequency would be mainly distributed in the section of 200-400 Hz.The high frequency oscillation of the overpressure can be related to the combustion-induced phase of the fast transition of the higher partial pressure of the water steam which may result from the explosion due to its great hydrogen content of the gas.