Research on Cellular Instabilities of Lean Premixed Syngas Flames under Various Hydrogen Fractions Using a Constant Volume Vessel

Energies

Hong-Meng Li²  Guo-Xiu Li¹  Zuo-Yu Sun²  Yue Zhai² 

[1] School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China;

关键词: premixed flame;    syngas flame;    intrinsic instabilities;    critical flame radius;   

DOI  :  10.3390/en7074710

来源: mdpi

【 摘 要 】

An experimental study of the intrinsic instabilities of H₂/CO lean (φ = 0.4 to φ = 1.0) premixed flames at different hydrogen fractions ranging from 0% to 100% at elevated pressure and room temperature was performed in a constant volume vessel using a Schlieren system. The unstretched laminar burning velocities were compared with data from the previous literature and simulated results. The results indicate that excellent agreements are obtained. The cellular instabilities of syngas-air flames were discussed and critical flame radii were measured. When hydrogen fractions are above 50%, the flame tends to be more stable as the equivalence ratio increases; however, the instability increases for flames of lower hydrogen fractions. For the premixed syngas flame with hydrogen fractions greater than 50%, the decline in cellular instabilities induced by the increase in equivalence ratio can be attributed to a reduction of diffusive-thermal instabilities rather than increased hydrodynamic instabilities. For premixed syngas flames with hydrogen fractions lower than 50%, as the equivalence ratio increases, the cellular instabilities become more evident because the enhanced hydrodynamic instabilities become the dominant effect. For premixed syngas flames, the enhancement of cellular instabilities induced by the increase in hydrogen fraction is the result of both increasing diffusive-thermal and hydrodynamic instabilities.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.