Microgravity experiments of single droplet combustion in oscillatory flow at elevated pressure

Yasuhiro Ogami, Satoru Sakurai, Syoichi Hasegawa, Mehdi Jangi, Hisashi Nakamura, Kentaro Yoshinaga, Hideaki Kobayashi

Research output: Contribution to journalConference articlepeer-review

10 Citations (Scopus)

Abstract

An experimental study for 1-butanol single droplet flames in constant and oscillatory flow fields was conducted under microgravity conditions at elevated pressure. In the constant flow experiments, flow velocities from 0 to 40 cm/s were tested. Using obtained data of d2, the burning rate constants were evaluated. The burning rate constant in the quiescent condition was also calculated successfully at high pressure by the extrapolation method based on the Frossling relation, In the oscillatory flow experiments, the flow velocities were varied from 0 to 40 cm/s at the frequencies of 2-40 Hz. Results showed that the burning rate constant during the droplet lifetime varied following the quasi-steady relation at 0.1 MPa; however, in the conditions with higher frequencies at 0.4 MPa, the average burning velocity became larger than that for the constant flow case with the velocity equivalent to the maximum velocity in the oscillatory flow. Under the condition where the burning rate constant increased, it was observed that the flame did not sufficiently move back upstream, leading to enhancement of the heat transfer from the flame to the droplet surface. Therefore, the instantaneous burning rate constant increased. To investigate the mechanism of such flame behavior, the ratio of two characteristic times, τfDf : flow oscillation characteristic time, τD: diffusion characteristic time), were compared. As the flow oscillatory frequency increased, τfD becomes smaller. τfD also became smaller at high pressure. If τfD is small due to the small mass diffusion rate, the droplet flame could not move back to the appropriate position for the minimum velocity in steady flow, leading to an increase of the burning rate constant, especially in the case of higher frequency at high pressure.

Original languageEnglish
Pages (from-to)2171-2178
Number of pages8
JournalProceedings of the Combustion Institute
Volume32 II
DOIs
Publication statusPublished - 2009 Mar 16
Event32nd International Symposium on Combustion - Montreal, QC, Canada
Duration: 2008 Aug 32008 Aug 8

Keywords

  • Burning rate constant
  • Droplet combustion
  • High pressure
  • Microgravity
  • Oscillatory flow

ASJC Scopus subject areas

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

Fingerprint Dive into the research topics of 'Microgravity experiments of single droplet combustion in oscillatory flow at elevated pressure'. Together they form a unique fingerprint.

Cite this