Experimental and theoretical analysis of cellular instability in lean H2-CH4-air flames at elevated pressures

Ekenechukwu C. Okafor, Yukihide Nagano, Toshiaki Kitagawa

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

Cellular instability in spherical propagating hydrogen-methane-air flames was studied experimentally in a constant volume chamber at an equivalence ratio of 0.8 and mixture temperature of 350 K. The mole fraction of hydrogen in the binary fuel was varied from 0 to 1.0 for mixture pressures up to 0.50 MPa. Cellular instability started earlier with an increase in the hydrogen mole fraction and mixture pressure. Self-acceleration of some of the propagating cellular flames was recorded and the acceleration increased with hydrogen mole fraction and mixture pressure. The unstretched laminar burning velocity was obtained from experiments and 1-D simulations of the outwardly propagating flames. Asymptotic theories gave a satisfactory qualitative prediction of the trends in the Markstein length, and the critical flame size for the onset of cellular instability. It was concluded that the Markstein length changed to a negative value at elevated pressure due to increased sensitivity of the burning velocity to thermo-diffusive effects.

Original languageEnglish
Pages (from-to)6581-6592
Number of pages12
JournalInternational Journal of Hydrogen Energy
Volume41
Issue number15
DOIs
Publication statusPublished - Apr 27 2016

All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Condensed Matter Physics
  • Energy Engineering and Power Technology

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