钝体阶梯扩管型微燃烧器内氢气-空气燃烧特性及协同性分析

Premixed hydrogen/air combustion characteristics and field synergy in micro combustor with bluff body and backward-facing step

为提高微燃烧器燃烧稳定性和燃烧效率,基于钝体直管和钝体阶梯扩管燃烧器进行微尺度燃烧数值模拟分析研究。研究结果表明:在钝体微燃烧器中加入阶梯扩管结构有助于促进火焰传播和扩大火焰稳定燃烧极限,而且两者的吹熄极限均随当量比(即完全燃烧所需的理论空气质量与实际供给的空气质量之比)的增大而增大;燃烧器的燃烧效率均随当量比和入口混合气速度的增大而降低,而且钝体直管型燃烧器的燃烧效率要比扩管型燃烧器低;散热损失比均随当量比增大呈先增大后降低,随入口速度增大而降低;钝体直管燃烧器协同数高于钝体阶梯扩管,两者的协同数都随入口的混合气速度增大先增大后降低再增大。

In order to improve combustion stability and combustion efficiency, micro-combustor mathematical simulationwas studied based on bluff body and backward-facing step combuster. The results show that the backward-facing step incombustion chamber can increase the flame propagation speed and expand the blow-off limits of flame, and bothincreases with the increase of the equivalence ratio （that is, the ratio of the theoretical air mass of complete combustion tothe actually air mass）. Furthermore, the combustion efficiency of combustors increases firstly and then decreases with thecontinual increase of inlet velocity or equivalence ratio, and combustion efficiency of combustor with backward-facingstep is higher than that of without step under the same conditions. While the heat dissipation ratio of the two types ofmicro combustors increases with the decrease of inlet velocity, and it increases firstly and then decreases with theincrease of equivalence ratio. With the increase of inlet mixed gas velocity, field synergy numbers of the micro combustorwith and without the backward-facing step increase firstly and then decrease, but increase again.