Laser ignition of methane-air mixtures at high pressures and optical diagnostics

H. Kopecek, M. Lackner, K. Iskra, Ch Forsich, D. Rüdisser, T. Neger, F. Winter, E. Wintner

    Research output: Chapter in Book/Report/Conference proceedingConference contributionResearchpeer-review

    Abstract

    Laser-induced ignition of methane-air mixtures of varied composition was investigated experimentally using nanosecond pulses generated by Q-switched Nd:YAG lasers (wavelength 1064 nm, 532 nm and 355 nm) at initial pressures up to 4 MPa. The minimum focal spot diameter was found to be about 20 μm for effective ignition, independent of the laser wavelength, indicating that small impurity particles provide the seeds for laser plasma generation. The minimum laser pulse energy needed for ignition ranged from 2-15 mJ decreasing reciprocally with initial pressure and with fuel equivalence ratio φ in a mixing regime of φ=0.91 to φ=0.56. Corresponding threshold intensities ranged from 1010 to 1011 W/cm2. In this way, evidence for a non-resonant breakdown mechanism was established. Optical in-situ diagnosis of water vapor concentration covering the whole timespan of the combustion process in a stationary high pressure vessel with four optical windows was performed involving linear absorption measurements over the entire spectral absorption linewidth by rapidly tuned diode laser radiation at 2.55 μm. Additionally, planar laser-induced fluorescence was measured in a time-resolving fashion yielding 3-dimensional determination of the OH concentrations during the process. To the knowledge of the authors, these are the first results on laser-induced ignition under laboratory conditions well above atmospheric pressure being relevant for several technical combustion systems.

    Original languageEnglish
    Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
    Subtitle of host publicationThe International Society for Optical Engineering
    EditorsH.P. Weber, V.I. Konov, T. Graf
    Pages331-342
    Number of pages12
    Volume5147
    DOIs
    Publication statusPublished - 2003
    EventALT'02 International Conference on Advanced Laser Technologies - Adelboden, Switzerland
    Duration: 15 Sep 200220 Sep 2002

    Conference

    ConferenceALT'02 International Conference on Advanced Laser Technologies
    CountrySwitzerland
    CityAdelboden
    Period15/09/0220/09/02

    Fingerprint

    ignition
    Ignition
    Methane
    methane
    Lasers
    air
    Air
    lasers
    plasma generators
    pressure vessels
    Laser pulses
    Q switched lasers
    pulses
    Well pressure
    laser plasmas
    wavelengths
    laser induced fluorescence
    equivalence
    water vapor
    YAG lasers

    Keywords

    • Absorption spectroscopy
    • Diode laser
    • High-pressure gas mixtures
    • Laser ignition
    • Laser-initiated combustion
    • Lean gas mixtures
    • Multipoint ignition
    • OH concentration
    • OH-radicals
    • PLIF

    ASJC Scopus subject areas

    • Electrical and Electronic Engineering
    • Condensed Matter Physics
    • Atomic and Molecular Physics, and Optics

    Cite this

    Kopecek, H., Lackner, M., Iskra, K., Forsich, C., Rüdisser, D., Neger, T., ... Wintner, E. (2003). Laser ignition of methane-air mixtures at high pressures and optical diagnostics. In H. P. Weber, V. I. Konov, & T. Graf (Eds.), Proceedings of SPIE - The International Society for Optical Engineering: The International Society for Optical Engineering (Vol. 5147, pp. 331-342) https://doi.org/10.1117/12.543678

    Laser ignition of methane-air mixtures at high pressures and optical diagnostics. / Kopecek, H.; Lackner, M.; Iskra, K.; Forsich, Ch; Rüdisser, D.; Neger, T.; Winter, F.; Wintner, E.

    Proceedings of SPIE - The International Society for Optical Engineering: The International Society for Optical Engineering. ed. / H.P. Weber; V.I. Konov; T. Graf. Vol. 5147 2003. p. 331-342.

    Research output: Chapter in Book/Report/Conference proceedingConference contributionResearchpeer-review

    Kopecek, H, Lackner, M, Iskra, K, Forsich, C, Rüdisser, D, Neger, T, Winter, F & Wintner, E 2003, Laser ignition of methane-air mixtures at high pressures and optical diagnostics. in HP Weber, VI Konov & T Graf (eds), Proceedings of SPIE - The International Society for Optical Engineering: The International Society for Optical Engineering. vol. 5147, pp. 331-342, ALT'02 International Conference on Advanced Laser Technologies, Adelboden, Switzerland, 15/09/02. https://doi.org/10.1117/12.543678
    Kopecek H, Lackner M, Iskra K, Forsich C, Rüdisser D, Neger T et al. Laser ignition of methane-air mixtures at high pressures and optical diagnostics. In Weber HP, Konov VI, Graf T, editors, Proceedings of SPIE - The International Society for Optical Engineering: The International Society for Optical Engineering. Vol. 5147. 2003. p. 331-342 https://doi.org/10.1117/12.543678
    Kopecek, H. ; Lackner, M. ; Iskra, K. ; Forsich, Ch ; Rüdisser, D. ; Neger, T. ; Winter, F. ; Wintner, E. / Laser ignition of methane-air mixtures at high pressures and optical diagnostics. Proceedings of SPIE - The International Society for Optical Engineering: The International Society for Optical Engineering. editor / H.P. Weber ; V.I. Konov ; T. Graf. Vol. 5147 2003. pp. 331-342
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    AB - Laser-induced ignition of methane-air mixtures of varied composition was investigated experimentally using nanosecond pulses generated by Q-switched Nd:YAG lasers (wavelength 1064 nm, 532 nm and 355 nm) at initial pressures up to 4 MPa. The minimum focal spot diameter was found to be about 20 μm for effective ignition, independent of the laser wavelength, indicating that small impurity particles provide the seeds for laser plasma generation. The minimum laser pulse energy needed for ignition ranged from 2-15 mJ decreasing reciprocally with initial pressure and with fuel equivalence ratio φ in a mixing regime of φ=0.91 to φ=0.56. Corresponding threshold intensities ranged from 1010 to 1011 W/cm2. In this way, evidence for a non-resonant breakdown mechanism was established. Optical in-situ diagnosis of water vapor concentration covering the whole timespan of the combustion process in a stationary high pressure vessel with four optical windows was performed involving linear absorption measurements over the entire spectral absorption linewidth by rapidly tuned diode laser radiation at 2.55 μm. Additionally, planar laser-induced fluorescence was measured in a time-resolving fashion yielding 3-dimensional determination of the OH concentrations during the process. To the knowledge of the authors, these are the first results on laser-induced ignition under laboratory conditions well above atmospheric pressure being relevant for several technical combustion systems.

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