Studies of radiation absorption on flame speed and flammability limit of CO2 diluted methane flames at elevated pressures

Zheng Chen, Xiao Qin, Bo Xu, Yiguang Ju, Fengshan Liu

Research output: Contribution to journalConference article

136 Scopus citations

Abstract

The effects of spectral radiation absorption on the flame speed at normal and elevated pressures were experimentally and numerically investigated using the CO2 diluted outwardly propagating CH4-O2-He flames. Experimentally, the laminar burning velocities of CH4-O 2-He-CO2 mixtures at both normal and elevated pressures (up to 5 atm) were measured by using a pressure-release type spherical bomb. The results showed that radiation absorption with CO2 addition increases the flame speed and extends the flammability limit. In addition, it was also shown that the increase of pressure augments the effect of radiation absorption. Computationally, a fitted statistical narrow-band correlated-k (FSNB-CK) model was developed and validated for accurate radiation prediction in spherical geometry. This new radiation scheme was integrated to the compressible flow solver developed to simulate outwardly propagating spherical flames. The comparison between experiment and computation showed a very good agreement. The results showed that the flame geometry have a significant impact on radiation absorption and that the one-dimensional planar radiation model was not valid for the computation of the flame speed of a spherical flame. An effective Boltzmann number is extracted from numerical simulation. Furthermore, the FSNB-CK model was compared with the grey band SNB model. It was shown that the grey band SNB model over-predicts the radiation absorption. It is concluded that quantitative prediction of flame speed and flammability limit of CO2 diluted flame requires accurate spectral dependent radiation model.

Original languageEnglish (US)
Pages (from-to)2693-2700
Number of pages8
JournalProceedings of the Combustion Institute
Volume31 II
DOIs
StatePublished - 2007
Event31st International Symposium on Combustion - Heidelberg, Germany
Duration: Aug 5 2006Aug 11 2006

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Mechanical Engineering
  • Physical and Theoretical Chemistry

Keywords

  • Burning velocity
  • CO addition
  • Flammability limit
  • Spectral dependent radiation

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