Schlieren visualization of blast extinguishment with laser-induced breakdown

Torikai, Hiroyuki; Soga, Yuki; Ito, Akihiko

doi:10.1016/j.proci.2016.06.131

Cited by 6 publications

(2 citation statements)

References 10 publications

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“…Supporting this, Dumitrache et al (2017) observed enhanced flame growth after suppressing the ejection with a pre-ionization pulse, which was thought to reduce flame stretching. Similarly, Torikai, Soga & Ito (2017) showed that the ejection can extinguish a flame. In contrast, figure 1 shows that hot gas carried by the ejection can ignite gas some distance from the breakdown, which is potentially important in an inhomogeneous mixture with length scales comparable to the size of the ejection.…”

Section: Introductionmentioning

confidence: 95%

Hydrodynamic ejection caused by laser-induced optical breakdown

2020

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Section: Introductionmentioning

confidence: 95%

Hydrodynamic ejection caused by laser-induced optical breakdown

2020

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“…From figure 6, it can be seen that ensemble averaging obscures the complex stochastic decay of the plume, interpreting it as a steady radial expansion of the toroidal part of the plume, accompanied by the growth of the central jet. This 'three-lobed' structure of the plume has been observed in a number of phase-locked average Schlieren images of the laser-induced plasma plumes [11,25,26].…”

Section: Resultsmentioning

confidence: 61%

NO PLIF flow visualization and time-resolved temperature distributions in laser induced breakdown plumes

Bekerom¹,

Jans²,

Adamovich³

2021

J. Phys. D: Appl. Phys.

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NO planar laser induced fluorescence (PLIF) is used to obtain images of laser-induced breakdown plasma plumes in NO-seeded nitrogen and dry air at near atmospheric pressure. Single-shot PLIF-images show that the plume development 5–50 μs after the breakdown pulse is fairly reproducible shot-to-shot, although the plume becomes increasingly stochastic on longer timescales, 100–500 μs. The stochastic behavior of the plume is quantified using probability distributions of the loci of the plume boundary. Analysis of the single-shot images indicates that the mixing of the plume with ambient gas on sub-ms time scale is insignificant. The induced flow velocity in the plume is fairly low, up to 30 m s−1, suggesting that laser breakdowns are ineffective for mixing enhancement in high speed flows. The ensemble-averaged PLIF images indicate the evolution of the plume from an initially elongated shape to near-spherical to toroidal shape, with a subsequent radial expansion and formation of an axial jet in the center. Temperature distributions in the plume in air are obtained from the NO PLIF images, using two rotational transitions in the NO(X, v′ = 0 → A, v″ = 0) band, J″ = 6.5 and 12.5 of the QR12 + Q2 branch. The results indicate that the temperature in the plume remains high, above 1000 K, for approximately 100 μs, after which it decays gradually, to below 500 K at 500 μs. The residual NO fraction in the plume is ∼0.1%, indicating that repetitive laser-assisted ignition may result in significant NO-generation. These measured temperature and velocity distributions can be used for detailed validation of kinetic models of laser-induced breakdown and assessment of their predictive capability.

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