点火条件对密闭管道内预混氢气/空气燃爆特性的影响

基于流体动力学软件Fluent，开展数值模拟，研究点火位置（距管左端壁面100、200和500 mm）、点火温度（1 000、1 500和2 000 K）和点火面积（管左端壁面处半径为50、35和20 mm的点火域）等点火条件对1 000 mm密闭管道中预混氢气/空气（H₂/air）燃爆特性的影响。研究表明:点火位置距管左端壁面越远，中间节点处温度越高，温升越快；不同点火温度下管内最高温升速率基本同步，且提高点火温度，使得燃烧反应更剧烈，能提高管内气体温升速率，但却降低管内的压力峰值；点火面积越小，预混H₂/air燃烧前期温升越快。当采用半径为35 mm的点火域和点火位置距管左端壁面100 mm的点火方式时，预混H₂/air燃爆的各项参数相对较高。不同点火条件对密闭管内气体的动能和内能的影响规律类似于其对管内气体的流速和温度的影响规律，而对涡量的影响不明显。

Influence of different ignition conditions on deflagration characteristics of a premixed mixture of H2 and air in a closed pipe

Numerical simulation was carried out by applying the fluid dynamics software Fluent to explore the influences of different ignition conditions,such as ignition locations (the distances from the left wall of the closed pipe are 100,200,and 500 mm,respectively),ignition temperatures (1000,1500 and 2000 K) and ignition area (ignition radius:50,35 and 20 mm) on the deflagration characteristics of the premixed H2/air mixture in a closed pipe with 1000 mm in length.The results show that,when the ignition positions are far away from the left wall of the closed pipe,the temperature of the intermediate node in the flow field is higher and the temperature rising is faster in the closed pipe.The rising rates of the maximum temperatures are basically synchronous on the conditions of the three different ignition temperatures (1000,1500 and 2000 K).Meanwhile,the combustion reaction of H2/air is more intense with the increasing of the ignition temperatures.The temperature rising rate in the closed pipe is accelerated.However,the peak pressure in the closed pipe is reduced.Moreover,the smaller the ignition area,the faster the temperature rising of H2/air in the early stage.When the radius of the ignition area is 35 mm and the ignition position away from the left side wall of the closed pipe is 100 mm,the deflagration parameters of H2/air are relatively higher.The influence of different ignition conditions on the kinetic energy and internal energy is similar to the influence of different ignition conditions on the velocity and temperature of the premixed gas,but the ignition conditions hardly influence the vorticity.