Experimental investigation on laminar burning velocities and flame intrinsic instabilities of lean and stoichiometric H2/CO/air mixtures at reduced, normal and elevated pressures
Experimental investigation on laminar burning velocities and flame intrinsic instabilities of lean and stoichiometric H2/CO/air mixtures at reduced, normal and elevated pressures
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DOI：
10.1016/j.fuel.2014.06.074
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发表时间：
2014-11-01
期刊：
影响因子：
7.4
通讯作者：
Zhou, Zihang
中科院分区：
文献类型：
--
作者：
Li, Hongmeng;Li, Guoxiu;Zhou, Zihang
实验采用纹影系统在定容燃烧室中进行，研究了不同氢馏分（30%、50%和70%）下H-2/CO/空气预混火焰在减压、常压和高压（0.05 MPa至0.4 MPa）下层流燃烧速度和内在不稳定性。未拉伸层流燃烧速度（S-u(0)）和L-b与以往文献的数据进行了比较。结果表明，所得结果非常吻合。对H-2/CO/空气火焰的内在不稳定性从流体动力不稳定性、扩散热不稳定性和体力不稳定性三个方面进行了解释和评价。此外，还测量了临界火焰半径和临界佩莱特数。结果表明：随着初始压力的增加，曲率对火焰的影响减弱，斜压扭矩对火焰的影响增强，H-2/CO/空气预混火焰的细胞不稳定性增强；随着当量比的增加，50%和70%的氢组分使细胞的不稳定性减弱；然而，当氢含量为30%时，由于扩散热不稳定性的影响，细胞不稳定性增强。氢组分的增加引起细胞不稳定性的增强。在低等效比下也观察到体-力不稳定性，并对火焰表面不规则裂纹的产生有抑制作用。(C) 2014 Elsevier Ltd.版权所有。
Experiments were conducted in a constant-volume combustion chamber by using a Schlieren system to study the laminar burning velocities and intrinsic instabilities of lean and stoichiometric (equivalence ratio from 0.3 to 1.0) H-2/CO/air premixed flames at various hydrogen fractions (30%, 50%, and 70%) at reduced, atmospheric, and elevated pressures (from 0.05 MPa to 0.4 MPa). The unstretched laminar burning velocities (S-u(0)) and L-b are compared with data from previous literature. Results indicate that excellent agreements are obtained. The intrinsic instabilities of H-2/CO/air flames were interpreted and evaluated in terms of hydrodynamic instability, diffusive-thermal instability, and body-force instability. Additionally, the critical flame radius and critical Peclet number were also measured. The results show that the cellular instabilities of H-2/CO/air premixed flames are enhanced due to the weaker influence of curvature and the enhanced intensity of baroclinic torque on the flame with the increase in initial pressure. With the increase in equivalence ratio, the cellular instabilities are weakened with hydrogen fractions of 50% and 70%; however, the cellular instabilities are enhanced with a hydrogen fraction of 30% because of the influence of diffusive-thermal instability. An increase in hydrogen fraction causes an enhancement in cellular instabilities. Body-force instability is also observed at low equivalence ratios and has an inhibitory effect on the generation of irregular cracks on the flame surface. (C) 2014 Elsevier Ltd. All rights reserved.