Saturated 2D-LIF of OH and 2D determination of effective collisional lifetimes in atmospheric pressure flames

Schäfer, M.; Ketterle, Wolfgang; Wolfrum, J.

doi:10.1007/bf00325493

Cited by 34 publications

(4 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The plot for the non-homogenized case characterizes clearly the stripes observed in many investigations, even where corrections for the inhomogeneous laser beam profile were performed (e.g. in [4,9,10]). Effectively, the application of the beam homogenizer smoothes drastically the spatial distribution of the averaged fluctuations (figure 6).…”

Section: Comparison Of the Statistical Fluctuations Of The Spatial Inmentioning

confidence: 70%

“…Especially at the outer regions of the laser beam, the intensity of the laser fluence can reach values, where the condition for saturation of the signal is not fulfilled. For example in saturation LIF for minor species concentration mapping [4] or in laser-induced incandescence (LII) techniques, where the soot mass-fraction is measured via the emitted Planck-radiation after laser illumination (e.g. [5][6][7]), signal saturation may be aimed [8].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Improvement of planar laser diagnostics by the application of a beam homogenizer

Pfadler¹,

Löffler²,

Beyrau³

et al. 2007

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

For planar laser diagnostics, a most uniform beam profile is highly desirable for two reasons: first, subsequent corrections for an inhomogeneous intensity distribution are time consuming and prevent on-line engineering assessment and second, temporal fluctuations cannot be corrected anyway. However, in general for combustion and flow diagnostics pulsed laser sources are used to achieve a high temporal resolution which typically possess a rather poor beam quality compared to continuously emitting laser sources. And, pulse to pulse fluctuations of the beam profile directly increase the noise in single-shot measurements. In this contribution we show the application of a micro-lens array based beam homogenizer whereby an almost homogeneous illumination of the region of in interest is achieved. This enables the on-line evaluation of the measured data without subsequent corrections. Thus a general advance of laser techniques towards engineering practice is achieved. Additionally, statistical fluctuations of the beam profile are strongly reduced by the homogenizer what directly improves the local standard deviation of the measurement. These benefits are demonstrated by means of planar laser-induced fluorescence (LIF) experiments.

show abstract

Section: Comparison Of the Statistical Fluctuations Of The Spatial Inmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Improvement of planar laser diagnostics by the application of a beam homogenizer

Pfadler¹,

Löffler²,

Beyrau³

et al. 2007

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

show abstract

“…Der Faktor ^eff Arad gi^t das Verhältnis der tatsächlich emittierenden Teilchen verglichen mit der Zahl der insgesamt angeregten Teilchen an. Q-jAn ist der Raumwinkel, aus dem die Fluoreszenzphotonen mit Hilfe der Empfangsoptik detektiert werden, £ der Verlustfaktor der Fluoreszenzphotonen durch Absorption und Streuung an den optischen Elementen ( des verwendeten elektronischen Übergangs des OHRadikals und das Ausblenden der zeitlichen Flanken des Laserpulses mit Hilfe einer sehr kurzen Kameraverschlußzeit (10 ns) kann die Fluoreszenz im Lichtband gesättigt werden [2], Auf diese Weise wird der Einfluß der Stoßlöschung auf das LIF-Signal weitgehend eliminiert. In Bild 1 kann man anhand der OHFluoreszenz die fraktale Struktur der Hauptreaktionszone, die das unverbrannte Erdgas-Luft-Gemisch (innen) vom verbrannten Bereich (außen) trennt, gut erkennen.…”

Section: Laserinduzierte Fluoreszenz Rayleighund Mie-streuungunclassified

Einsatz der Lasermeßtechnik zur Diagnostik und Optimierung von technischen Verbrennungsprozessen

Eberl

Sick

Wolfrum

1996

tm - Technisches Messen

View full text Add to dashboard Cite

Schlagwörter: In-situ-Laserspektroskopie, Absorptionsspektroskopie, laserinduzierte Fluoreszenz, RayleighStreuung, NIR-Diodenlaser In den letzten Jahren konnten eine Reihe von laserspektroskopischenVerfahren zur In-situ-Analyse von technischen Verbrennungsvorgängen entwickelt werden. Der Einsatz der laserinduzierten Fluoreszenz (LIF), der Rayleigh-und Mie-Streuung, der Excimerlaser-induzierten Fragmentierungsfluoreszenz (ELIF) sowie der NIR-Diodenlaserabsorption wird in Gasflammen, Automobilmotoren, druckaufgeladenenKohle-Wirbelschichtreaktoren sowie Kraft-Wärme-Kopplungsanlagen zur thermischen Reststoffverwertung vorgestellt. Laser-based non intrusive measurements of concentrations and temperatures in technical combustion devicesVarious laser spectroscopic methods were developed during recent years and have become a valuable tool to study technical combustion processes. Examples for the application of laser-induced fluorescence (LIF), Rayleigh-and Mie-scattering, fragmentation fluorescence (ELIF), NIR emission and absorption spectroscopy in premixed gas flames automobile engines, pressurized fluidized-bed coal combustion and waste incinerators are described.

show abstract

“…Because of its strong signal intensity, LIF has been applied to 2D detection of temperature and species concentration [7,8]. These applications include basic research burners [9][10][11][12][13][14][15][16][17][18][19][20][21], industrial burners [4,22,23], gas turbines [4,24], and diesel engines [4,5,[25][26][27][28][29][30]. Recently, 3D detection [31,32] has also been shown to be capable of detecting several 2D sections simultaneously [33].…”

Section: Introductionmentioning

confidence: 99%

Industrial applications of temperature and species concentration monitoring using laser diagnostics

Deguchi¹,

Noda²,

Fukuda³

et al. 2002

Meas. Sci. Technol.

View full text Add to dashboard Cite

Industrial applications of laser diagnostics have been demonstrated for the purpose of clarifying combustor chemical reaction mechanisms, as well as temperature and harmful substance monitoring in large-scale burners and commercial plant exhaust ducts, and the combustion control of commercial plants. Laser induced fluorescence (LIF), laser induced breakdown spectroscopy (LIBS), and tunable diode laser absorption spectroscopy (TDLAS) have accordingly been applied in various industrial fields. In this study, temperature and species concentration were measured inside gas turbine combustors, a diesel engine, and a large-scale industrial burner using LIF. This technique introduces a new tool with respect to practical combustors for the analysis of NO formation characteristics, turbulent flame front structure, and differences between standard and improved combustors. On-line monitoring of trace elements to the ppb level was also successfully demonstrated using LIBS. The automated LIBS unit was found to be capable of monitoring trace element concentration fluctuations at ppb levels with a 1 min detection time under actual plant conditions. In addition, real-time measurement of O2 and CO concentrations in a commercial incinerator furnace was performed using TDLAS to improve the combustion control. By using the multiple-point laser measurement results to control secondary air allocation, higher secondary combustion efficiency was achieved, and CO concentration (considered to be a substitute indicator for dioxins) was reduced from 11.9 to 8.0 ppm.

show abstract

Saturated 2D-LIF of OH and 2D determination of effective collisional lifetimes in atmospheric pressure flames

Cited by 34 publications

References 29 publications

Improvement of planar laser diagnostics by the application of a beam homogenizer

Improvement of planar laser diagnostics by the application of a beam homogenizer

Einsatz der Lasermeßtechnik zur Diagnostik und Optimierung von technischen Verbrennungsprozessen

Industrial applications of temperature and species concentration monitoring using laser diagnostics

Contact Info

Product

Resources

About