Laser Ignition of Propane-Air Mixtures Using a Dual-Pulse Technique

Dumitrache, Ciprian; VanOsdol, Rachel; Limbach, Christopher; Yalin, Azer P.

doi:10.2514/6.2017-1976

Cited by 8 publications

(2 citation statements)

References 23 publications

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“…Diagnostic measurements of gas temperature and electron density of the laser plasmas were performed by Rayleigh and Thomson scattering. Details on these methods have been presented in our past publications 19,41,42 and here we summarize the essential features. The probe beam is nominally aligned to pass through the center of the laser plasma to allow 1-D (line) measurement of (combined) Rayleigh and Thomson scattering from the laser plasma (see Fig.…”

Section: Methodsmentioning

confidence: 99%

Resonant dual-pulse laser ignition technique based on oxygen REMPI pre-ionization

Dumitrache

Butte

Yalin

2020

Sci Rep

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This contribution investigates a novel laser ignition method based on a dual-pulse resonant pre-ionization scheme. The first laser pulse efficiently creates initial gas ionization (seed electrons) through a 2 + 1 resonantly-enhanced multiphoton ionization (REMPI) scheme targeting molecular oxygen (λ ~ 287.6 nm). This pulse is followed by a second non-resonant near-infrared pulse (λ = 1064 nm) for energy addition into the gas via inverse bremsstrahlung absorption. The sequence of two pulses creates a laser induced plasma that exhibits high peak electron number density and temperature (ne ~ 8 × 1017 cm-3 at t = 100 ns and T ~ 8000 K at t = 10 μs, respectively). These plasma parameters are similar to those attained for typical single-pulse near-infrared laser plasmas but with the advantage of substantially lower pulse energy (by factor of ~ 2.5) in the dual-pulse REMPI case. A combustion study focusing on ignition of propane/air mixtures shows that the dual-pulse REMPI method leads to an extension of the lean flammability limit, and an increase in combustion efficiency near the lean limit, as compared to laser ignition with a single NIR pulse. The measurement results and observed gas dynamics are discussed in the context of their impact on combustion applications.

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Section: Methodsmentioning

confidence: 99%

Resonant dual-pulse laser ignition technique based on oxygen REMPI pre-ionization

Dumitrache

Butte

Yalin

2020

Sci Rep

Self Cite

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“…The dual-pulse laser scheme combining UV 266 nm and NIR 1064 nm laser beams has demonstrated an increase in flame speed and successful ignition of a lean fuel-air mixture below the flammability limit [22][23][24]. Recent experimental studies [25] have shown that the dual-pulse approach not only reduce energy consumption and energy losses associated with the shockwave propagation, but also enhance combustion efficiency especially, when igniting lean methane-air, propaneair, and hydrogen-air mixtures.…”

Section: Introductionmentioning

confidence: 99%

Plasma defocusing in dual-pulse laser ignition

Tropina¹,

Pokharel²,

New-Tolley³

et al. 2021

J. Phys. D: Appl. Phys.

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The paper presents simulation results of hydrogen-air mixture ignition by an ultraviolet followed by a near-infrared laser pulse. We used the three-temperature plasma model in a combination with the beam propagation method. Effect of plasma defocusing on the ignition kernel development is reported. It is shown that the plasma generated by the pre-ionizing pulse affects the position of the focal region of the second heating pulse with resulting changes in the distribution of the laser energy absorption, electron and radical production and ignition kernel dynamics. For the case with the defocusing effect we observed a shift of the peaks of translational and vibrational temperatures towards the direction of the laser pulse and two peaks on the axial profile of the electron temperature, reflecting local changes both in Joule heating and electron energy losses.

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