The effects of unburned-gas temperature on the characteristics of cellular premixed flames generated by hydrodynamic and diffusive-thermal instabilities in large space: Fractal dimension of cellular-flame fronts

Satoshi Kadowaki, Taisuke Washio, Thwe Thwe Aung, Wataru Yamazaki, Toshiyuki Katsumi, Hideaki Kobayashi

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

The effects of unburned-gas temperature on the characteristics of cellular premixed flames generated by hydrodynamic and diffusive-thermal instabilities were numerically investigated. Two-dimensional reactive flow was calculated in large space, based on the compressible Navier-Stokes equations including a one-step irreversible chemical reaction. The dynamic behavior of cellular premixed flames, i.e. the coalescence and division of cells, appeared in large space owing to intrinsic instability. The behavior of flame fronts became more unstable with a decrease in unburned-gas temperature, even though the burning velocity of a planar flame reduced. This was due to the strength of thermal-expansion effects and to the enlargement of Zeldovich numbers. We found that the average burning velocity of a cellular flame normalized by that of a planar flame increased as the unburned-gas temperature became lower and the space size became larger. To elucidate the increase of burning velocity, we proposed the new model and showed that the normalized increment factor of burning velocity became larger under low unburned-gas temperature. In addition, we performed fractal analysis to consider the fractal dimension for three-dimensional flow. The obtained fractal dimension corresponding to laminar flames was nearly identical to the experimental and numerical results of turbulent flames.

Original languageEnglish
Article numberJTST0015
JournalJournal of Thermal Science and Technology
Volume12
Issue number1
DOIs
Publication statusPublished - 2017

Keywords

  • Cellular premixed flame
  • Dynamic behavior
  • Fractal dimension
  • Intrinsic instability
  • Unburned-gas temperature

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Materials Science(all)
  • Instrumentation
  • Engineering (miscellaneous)

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