A numerical study of the laminar flame speed of stratified methane/air flames

✍ Scribed by A. Pires Da Cruz; A.M. Dean; J.M. Grenda

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 212 KB
• Volume: 28
• Category: Article
• ISSN: 1540-7489
• DOI: 10.1016/s0082-0784(00)80597-4

✦ Synopsis

Freely propagating laminar methane/air flames were modeled for spatially stratified equivalence ratio conditions at atmospheric pressure. The GRI 2.11 mechanism was used with a modified version of the Lawrence Livermore National Laboratory HCT code to describe the reaction kinetics. Results showed that the laminar flame speed was strongly affected by the equivalence ratio gradient and by the burned gas composition and temperature. Production of molecular hydrogen from the original fuel and its transport to the reaction zone as well as heat transfer from the burned to the fresh gases are key factors in understanding the influence of stratification on laminar flame speed. Combinations of different mixture stratification conditions can either enhance or reduce the flame velocity when compared with homogeneous mixtures. Mixture stratification is also responsible for higher flame resistance to extinction both on the lean and rich sides of the equivalence ratio. The importance of heat and mass transfer on the observed results implies that their extrapolation to high pressure and to turbulent systems must be made with care.