微型凹腔燃烧器内氢气/空气的预混燃烧特性

Combustion characteristics of hydrogen/air mixture in a micro-combustor with cavities

使用计算流体动力学软件FLUENT,并采用详细的化学反应机理,对当量比为0.5的氢气/空气预混气在带凹腔的平板型微通道内的燃烧特性进行了数值模拟.探讨了进气速度和凹腔的长深比对微通道内的温度场、燃烧效率和排烟温度的影响.计算结果表明:随着进气速度的增大,火焰被吹向下游,并且使火焰变得狭长,这会使得壁温分布更加均匀;在同一长深比下,燃烧效率随着进气速度的增加而降低,而排烟温度随着进气速度的增大先升高后降低;当长深比从1增大到3时,增大凹腔的长深比能拓展吹熄极限;长深比从3增大到4时,其吹熄极限相同.

Premixed combustion of a hydrogen/air mixture in a planar micro-channel with cavities was numerically simulated by FLUENT with detailed chemical reaction mechanism.The equivalence ratio of the mixture was 0.5.Effects of the inlet mixture velocity and length-depth ratio of the cavities on the temperature field,combustion efficiency and exhaust gas temperature were investigated.The results show that with the increase of inlet velocity,the flame front shifts downstream and becomes longer and narrower,and the temperature of outer wall becomes more uniform.Moreover,for the same length-depth ratio,the combustion efficiency decreases with the increase of inlet velocity;however,the exhaust gas temperature first increases and then decreases with the increase of inlet velocity.Furthermore,the blow-off limit is extended as the length-depth ratio is increased from 1to 3,and then remained unchanged when width-depth ratio is raised from 3to 4.