68th Annual Meeting of the APS Division of Fluid Dynamics (November 22, 2015 — November 24, 2015)

P0006: Schlieren imaging of laser-induced ignition and flame propagation by single and successive laser pulses

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Authors

• Lydia Wermer, Ph.D. Student, Aerospace Program, Department of Mechanical Engineering, Worcester Polytechnic Institute
• Seong-kyun Im, Assistant Professor, Aerospace Program, Department of Mechanical Engineering, Worcester Polytechnic Institute
• Moon Soo Bak, Assistant Professor, School of Mechanical Engineering, Sungkyunwan University, South Korea

DOI: https://doi.org/10.1103/APS.DFD.2015.GFM.P0006

Time-sequential schlieren images are shown of laser-induced spark ignition by a single laser pulse (top row) and by successive laser pulses separated by 600 μs (bottom row). Laser-induced sparks were produced at the exit of a nozzle in a stoichiometric premixed methane-air flow at 4 m/s bulk speed. The flame propagation for successive laser sparks separated by a time interval of 600 μs was initially smaller than the single laser pulse propagation, but as the two laser pulses interact, they produce a turbulent flame structure which increases the flame propagation speed. The increased speed is determined by comparing images at 5 ms after the first breakdown where the flame propagation for successive pulses is further downstream than the flame propagation for a single laser pulse.