Ignition and flame propagation enhancement by dual-pulsed laser-induced breakdown

Lydia Wermer, Joseph K. Lefkowitz, Timothy Ombrello, Seong Kyun Im

Research output: Contribution to conferencePaper

Abstract

Ignition probability and flame growth rates of single and dual-pulse laser-induced breakdown were experimentally investigated in a turbulent premixed methane-air flow to examine enhancement by dual-pulse at fuel-lean conditions. The ignition and flame propagation was visualized with high-speed schlieren imaging. Successful ignition was confirmed by CO2 filtered infrared imaging. Experiments were performed in a 3.8 cm by 3.8 cm square cross-section wind tunnel with a bulk velocity 10 m/s, equivalence ratios of 0.45 to 0.6 and total laser energy of 25 mJ per pulse. Ignition probability enhancement by dual-pulsed laser-induced breakdown with time intervals in the tens of nanosecond ranges occurred in premixed flows with equivalence ratios of 0.45 to 0.5 where pulse-to-pulse energy coupling enlarged the spark area and increased the available ignition energy. Dual-pulsed laser-induced breakdown with time intervals between pulses of hundreds of microseconds had increased flame growth rates in premixed flows with equivalence ratios 0.5 to 0.6 where conditions were sufficient for the first breakdown to ignite the mixture before arrival of the second breakdown. The hot plume induced by the second breakdown interacted with the ignition kernel induced by the first breakdown increasing the flame surface area and the flame growth rate.

Original languageEnglish
Publication statusPublished - 2017 Jan 1
Externally publishedYes
Event10th U.S. National Combustion Meeting - College Park, United States
Duration: 2017 Apr 232017 Apr 26

Conference

Conference10th U.S. National Combustion Meeting
CountryUnited States
CityCollege Park
Period17/4/2317/4/26

Fingerprint

flame propagation
Pulsed lasers
ignition
Ignition
pulsed lasers
breakdown
propagation
augmentation
flames
pulses
Laser pulses
equivalence
intervals
Methane
Infrared imaging
Electric sparks
wind tunnels
air flow
Wind tunnels
sparks

Keywords

  • Ignition
  • Laser-induced breakdown
  • Lean mixture
  • Schlieren imaging

ASJC Scopus subject areas

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

Cite this

Wermer, L., Lefkowitz, J. K., Ombrello, T., & Im, S. K. (2017). Ignition and flame propagation enhancement by dual-pulsed laser-induced breakdown. Paper presented at 10th U.S. National Combustion Meeting, College Park, United States.

Ignition and flame propagation enhancement by dual-pulsed laser-induced breakdown. / Wermer, Lydia; Lefkowitz, Joseph K.; Ombrello, Timothy; Im, Seong Kyun.

2017. Paper presented at 10th U.S. National Combustion Meeting, College Park, United States.

Research output: Contribution to conferencePaper

Wermer, L, Lefkowitz, JK, Ombrello, T & Im, SK 2017, 'Ignition and flame propagation enhancement by dual-pulsed laser-induced breakdown', Paper presented at 10th U.S. National Combustion Meeting, College Park, United States, 17/4/23 - 17/4/26.
Wermer L, Lefkowitz JK, Ombrello T, Im SK. Ignition and flame propagation enhancement by dual-pulsed laser-induced breakdown. 2017. Paper presented at 10th U.S. National Combustion Meeting, College Park, United States.
Wermer, Lydia ; Lefkowitz, Joseph K. ; Ombrello, Timothy ; Im, Seong Kyun. / Ignition and flame propagation enhancement by dual-pulsed laser-induced breakdown. Paper presented at 10th U.S. National Combustion Meeting, College Park, United States.
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AB - Ignition probability and flame growth rates of single and dual-pulse laser-induced breakdown were experimentally investigated in a turbulent premixed methane-air flow to examine enhancement by dual-pulse at fuel-lean conditions. The ignition and flame propagation was visualized with high-speed schlieren imaging. Successful ignition was confirmed by CO2 filtered infrared imaging. Experiments were performed in a 3.8 cm by 3.8 cm square cross-section wind tunnel with a bulk velocity 10 m/s, equivalence ratios of 0.45 to 0.6 and total laser energy of 25 mJ per pulse. Ignition probability enhancement by dual-pulsed laser-induced breakdown with time intervals in the tens of nanosecond ranges occurred in premixed flows with equivalence ratios of 0.45 to 0.5 where pulse-to-pulse energy coupling enlarged the spark area and increased the available ignition energy. Dual-pulsed laser-induced breakdown with time intervals between pulses of hundreds of microseconds had increased flame growth rates in premixed flows with equivalence ratios 0.5 to 0.6 where conditions were sufficient for the first breakdown to ignite the mixture before arrival of the second breakdown. The hot plume induced by the second breakdown interacted with the ignition kernel induced by the first breakdown increasing the flame surface area and the flame growth rate.

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