Laser-induced plasma in methane and dimethyl ether for flame ignition and combustion diagnostics

Kiefer, Johannes; Tröger, Johannes W.; Li, Z. S.; Aldén, Marcus

doi:10.1007/s00340-010-4338-6

Cited by 59 publications

(19 citation statements)

References 27 publications

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“…CH 4 and C 3 H 8 ) and air flames on low pressure premixed chamber by LIBS [5][6][7][8][9][10]. Experiments in which the laser induced plasma ignition and equivalence ratio measurements by LIBS were achieved simultaneously have also been carried out [11][12][13]. Additionally, some LIBS on-line investigations were accomplished.…”

Section: Introductionmentioning

confidence: 99%

Laser induced breakdown spectroscopy for local equivalence ratio measurement of kerosene/air mixture at elevated pressure

Zhang

et al. 2012

Optics and Lasers in Engineering

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The quantitative local equivalence ratio measurements of premixed kerosene/air gas at elevated pressure by the laser induced breakdown spectroscopy (LIBS) technique were preformed in a high temperature test cell, which was designed and manufactured for simulated supersonic combustion state. According to in-situ experimental conditions in supersonic combustion, the correlations between the values of emission intensity ratio of H/O, H/N and the equivalence ratio of premixed kerosene/air mixture in different gas pressures was established. The dependence of the FWHM of H a on pressure of the mixture was also measured. Therefore, the laser diagnostic method for quantitative local equivalence ratio measurements of kerosene/air mixture by the LIBS technique in supersonic combustion was developed in laboratory. The fundamental data was prepared for on-line quantitative local equivalence ratio measurements of kerosene/air mixture in supersonic combustion experiments.

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Section: Introductionmentioning

confidence: 99%

Laser induced breakdown spectroscopy for local equivalence ratio measurement of kerosene/air mixture at elevated pressure

Zhang

et al. 2012

Optics and Lasers in Engineering

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“…To investigate the role played by the local ER in determining the ultimate laser ignition results, the local ER is measured using the laser-induced breakdown spectroscopy (LIBS) technique. Several groups 26–32 showed that LIBS is capable of providing real-time, spatially and temporally resolved data. By generating a laser spark in the combustion gas mixture and correlating the ER with the intensity ratio of two atomic lines 26–28,31,32 originating from the representative elements of the fuel and oxidizer, or with the intensity of the molecular radical emission, such as CN, 30 the local ER can be obtained from the spark emission spectrum.…”

Section: Methodsmentioning

confidence: 99%

“…The laser spark spectra during the ignition process are measured using a portable ungated spectrometer (USB 4000; Ocean Optics). Several groups 30–32 demonstrated the reliability of the ungated spectrometer for ER measurements. The laser spark is imaged 1:1 onto the fiber head of the spectrometer using a 100 mm focal length quartz lens, and then the recorded spectra are saved using OOI Base32 software (Ocean Optics).…”

Section: Methodsmentioning

confidence: 99%

Laser Spark Ignition of Premixed Methane–Air Mixtures: Parameter Measurements and Determination of Key Factors for Ultimate Ignition Results

Smith

Omenetto

2014

Appl Spectrosc

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In this study, we present an experimental investigation of the parameters of the laser spark ignition of premixed methane-air mixtures and the determination of the key factors for the ultimate ignition result. Ignition is achieved in a mesh honeycomb burner using the 1064 nm output of a neodymium-doped yttrium aluminum garnet (Nd : YAG) laser. All pertinent laser ignition parameters, including the minimum ignition energy, the ignition time and blow out time, and the effects that the variation of experimental conditions, such as the spark energy, ignition position, equivalence ratio (ER), and flow rate, have on these parameters have been addressed systematically. To identify the key factors for the ultimate result of laser ignition, several parameters of the ignition processes are measured simultaneously, with an emphasis given to the temporal behavior of the hydroxyl (OH) radicals in relation to the data regarding the spark energy and the local ER. A clear finding of the study is that successful ignition events are always related to higher OH radical photon emissions, considered to be proportional to the concentration level of the OH radicals present, thus indicating a direct link between the OH level at early times (on a microsecond scale) and the ultimate result of laser ignition. Two-dimensional correlation plots of the spark energy, local ER, and OH radical photon count at early times with the ultimate results of laser ignition indicate that the spark energy and local ER do not play a critical role in determining the success or failure of the ignition and that the OH concentration in the early time range is the key factor in determining the final fate of laser ignition. Finally, on the basis of the results obtained here and in the existing literature, some considerations of the mechanism of laser ignition are presented.

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“…For this, the spectral lines of oxygen (777 nm) and hydrogen (656 nm) are detected 500 ns after the laser pulse with an exposure time of 60 ns for different values of f. A similar linear correlation between the ratio of oxygen to hydrogen lines and f was determined according to the literature. [36][37][38] Thus, it is assumed that a desired methane/air mixture is at the ignition point for all investigated flow velocities.…”

Section: Analysis Of Shock Wave Propagation and Flame Kernel Formationmentioning

confidence: 99%

Pulse train ignition with passively Q-switched laser spark plugs

Lorenz

Bärwinkel

Stäglich

et al. 2015

International Journal of Engine Research

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Leaner burning and downsizing are two concepts pursued by engine developers to reduce fuel consumption and emissions. Both approaches lead to increasing challenges concerning ignition, as these concepts are typically associated with an increase in flow velocity and degree of turbulence as well as raised pressure at the moment of ignition. In this context, the use of miniaturized passively Q-switched laser spark plugs with pulse train ignition is considered as a promising alternative to conventional spark plugs.However, the application of these passively Q-switched laser spark plugs inevitably leads to the question of optimum pulse train parameters. For a better understanding, this study deals with improved flame formation by passively Qswitched laser pulse train ignition under engine-like conditions. The entire ignition process is investigated with a special focus on interactions of consecutive pulses. Therefore, three methods are combined: energy transfer measurements from laser pulse to plasma with high temporal and spatial resolution show the breakdown process depending on different pressures and fluid mixtures. The temperature decrease in the induced plasma is analyzed with measurement strategies for temporal high-resolved plasma spectroscopy especially adapted to passively Q-switched lasers. In combination with high-speed schlieren measurements, the changing local ignition conditions during pulse train ignition are demonstrated. The experiments show how consecutive pulses interact and contribute to the ignition in case of a gas flow. The used prototypes of laser spark plugs are provided by Robert Bosch GmbH.

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Laser-induced plasma in methane and dimethyl ether for flame ignition and combustion diagnostics

Cited by 59 publications

References 27 publications

Laser induced breakdown spectroscopy for local equivalence ratio measurement of kerosene/air mixture at elevated pressure

Laser induced breakdown spectroscopy for local equivalence ratio measurement of kerosene/air mixture at elevated pressure

Laser Spark Ignition of Premixed Methane–Air Mixtures: Parameter Measurements and Determination of Key Factors for Ultimate Ignition Results

Pulse train ignition with passively Q-switched laser spark plugs

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