Strain rate effect on sooting characteristics in laminar counterflow diffusion flames

Yu Wang, Suk Ho Chung

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

The effects of strain rate, oxygen enrichment and fuel type on the sooting characteristics of counterflow diffusion flames were studied. The sooting structures and relative PAH concentrations were measured with laser diagnostics. Detailed soot modeling using recently developed PAH chemistry and surface reaction mechanism was performed and the results were compared with experimental data for ethylene flames, focusing on the effects of strain rates. The results showed that increase in strain rate reduced soot volume fraction, average size and peak number density. Increase in oxygen mole fraction increased soot loading and decreased its sensitivity on strain rate. The soot volume fractions of ethane, propene and propane flames were also measured as a function of global strain rate. The sensitivity of soot volume fraction to strain rate was observed to be fuel dependent at a fixed oxygen mole fraction, with the sensitivity being higher for more sooting fuels. However, when the soot loadings were matched at a reference strain rate for different fuels by adjusting oxygen mole fraction, the dependence of soot loading on strain rate became comparable among the tested fuels. PAH concentrations were shown to decrease with increase in strain rate and the dependence on strain rate is more pronounced for larger PAHs. Soot modeling was performed using detailed PAH growth chemistry with molecular growth up to coronene. A qualitative agreement was obtained between experimental and simulation results, which was then used to explain the experimentally observed strain rate effect on soot growth. However, quantitatively, the simulation result exhibits higher sensitivity to strain rate, especially for large PAHs and soot volume fractions.
Original languageEnglish (US)
Pages (from-to)433-444
Number of pages12
JournalCombustion and Flame
Volume165
DOIs
StatePublished - Jan 20 2016

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Physics and Astronomy(all)
  • Chemical Engineering(all)
  • Chemistry(all)
  • Fuel Technology

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