Spherical gas-fueled cool diffusion flames

Minhyeng Kim, Kendyl A. Waddell, Peter B. Sunderland, Vedha Nayagam, Dennis P. Stocker, Daniel L. Dietrich, Yiguang Ju, Forman A. Williams, Phillip Irace, Richard L. Axelbaum

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


An improved understanding of cool diffusion flames could lead to improved engines. These flames are investigated here using a spherical porous burner with gaseous fuels in the microgravity environment of the International Space Station. Normal and inverse flames burning ethane, propane, and n-butane were explored with various fuel and oxygen concentrations, pressures, and flow rates. The diagnostics included an intensified video camera, radiometers, and thermocouples. Spherical cool diffusion flames burning gases were observed for the first time. However, these cool flames were not readily produced and were only obtained for normal n-butane flames at 2 bar with an ambient oxygen mole fraction of 0.39. The hot flames that spawned the cool flames were 2.6 times as large. An analytical model is presented that combines previous models for steady droplet burning and the partial-burning regime for cool diffusion flames. The results identify the importance of burner temperature on the behavior of these cool flames. They also indicate that the observed cool flames reside in rich regions near a mixture fraction of 0.53.

Original languageEnglish (US)
Pages (from-to)1647-1656
Number of pages10
JournalProceedings of the Combustion Institute
Issue number2
StatePublished - Jan 2023

All Science Journal Classification (ASJC) codes

  • General Chemical Engineering
  • Mechanical Engineering
  • Physical and Theoretical Chemistry


  • Formaldehyde
  • Intensified video camera
  • Microgravity combustion
  • Porous burner


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