催化微燃烧室内氢气和氧气预混合燃烧特性

Combustion Characteristic of Premixed Hydrogen / Oxygen Mixture in Catalytic Micro-combustor

针对带催化的微燃烧室内部氢氧预混合燃烧过程,利用CFD计算软件建立模型进行数值模拟,在实验验证的基础上改变入口参数,分析了表面反应与气相反应的相互作用以及催化反应对火焰吹熄极限的影响。结果表明,表面反应对气相反应中间产物的消耗会使气相反应强度减弱;在催化剂表面附近的反应以表面反应为主,在远离催化剂表面的反应以气相反应为主。催化剂的添加能够极大地拓宽火焰吹熄极限,在当量比为1.0时,催化燃烧室和无催化燃烧室的吹熄极限分别为46、22 m/s。在当量比为1.0时,表面反应强度最高,此时燃烧室出口截面温度最高。

The premixed hydrogen / oxygen combustion process in a catalytic micro-combustor was numerically simulated with CFD software. The interaction between gas-phase and catalytic reaction was analyzed by changing inlet parameters on the basis of experimental verification. Meanwhile,the blow-off limits for combustor with and without catalyst were also investigated. The results showed that gas-phase reaction was subdued with the intermediate products consumed in catalytic reaction. At the same velocity,the flame temperature of catalytic combustor was lower than that of non-catalytic combustor. The OH mass fraction near up-wall of Pt cell in catalytic combustion chamber was also lower than that near up-wall of Si C cell in non-catalytic combustor. While owing to the exothermic surface reaction with Pt cell,the temperature of Pt cell in catalytic combustor was higher than that of Si C cell in non-catalytic combustor. Catalytic reaction was dominant near the surface of catalyst,while gas-phase reaction was dominant away from the surface. The OH mass fraction distribution trend near the inner up-wall in catalytic combustor was consistent with that near the inner up-wall in non-catalytic combustor. The blowoff limit can be widened by adding catalyst. The blow-off limits for combustor with and without catalyst were 46 m / s and 22 m / s,respectively. At equivalence ratio of 1. 0,the strongest activity of catalytic was shown,and the gas-phase reaction was obviously restrained. With the increase of equivalence ratio,the mean temperature of out-wall was risen at the beginning and then it was dropped later. The highest mean temperature of out-wall was achieved with equivalence ratio of 1. 0.