Laser Diagnostics for Temperature and Species in Unsteady Combustion

Eckbreth, Alan C.

doi:10.1007/978-94-009-1620-3_18

Cited by 819 publications

(675 citation statements)

References 33 publications

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“…The hydroxyl radical (OH) is used as a marker of the reaction zone as it is an important intermediate species that is formed during the combustion process [12,13]. The temporal development of the hot jet penetration into the fresh mixture is observed using combined laser Schlieren and OH-LIF [14] visualisation sequenced at high repetition rates. Experiments were performed with different pressure ratios over the nozzle and different nozzle diameters in order to study the influence of different jet velocities on the gas expansion and ignition processes.…”

Section: Introduction and Theoretical Backgroundmentioning

confidence: 99%

Detailed investigation of ignition by hot gas jets

Sadanandan

Markus

Schießl

et al. 2007

Proceedings of the Combustion Institute

107

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Experimental and numerical investigations of the ignition of hydrogen/air mixtures by jets of hot exhaust gases are reported. An experimental realisation of such an ignition process, where a jet of hot exhaust gas impinges through a narrow nozzle into a quiescent hydrogen/air mixture, possibly initiating ignition and combustion, is studied. High-speed laser-induced fluorescence (LIF) image sequences of the hydroxyl radical (OH) and laser Schlieren methods are used to gain information about the spatial and temporal evolution of the ignition process. Recording temporally resolved pressure traces yields information about ambient conditions for the process. Numerical experiments are performed that allow linking these observables to certain characteristic states of the gas mixture. The outcome of numerical modelling and experiments indicates the important influence of the hot jet temperature and speed of mixing between the hot and cold gases on the ignition process. The results show the quenching of the flame inside the nozzle and the subsequent ignition of the mixture by the hot exhaust jet. These detailed examinations of the ignition process improve the knowledge concerning flame transmission out of electrical equipment of the type of protection flameproof enclosure.

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Section: Introduction and Theoretical Backgroundmentioning

confidence: 99%

Detailed investigation of ignition by hot gas jets

Sadanandan

Markus

Schießl

et al. 2007

Proceedings of the Combustion Institute

107

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“…[1][2][3][4][5] The line-imaging Raman/Rayleigh scattering instrument at Sandia National Laboratories (SNL) provides instantaneous measurements of temperature and major species concentrations (N 2 , O 2 , CO 2 , CO, H 2 O, H 2 and CH 4 ) in flames, over a 6 mm probe line, with a spatial resolution of ~100 microns. The instrument is routinely applied to measurements in laboratory-scale flames that are specifically designed to advance the understanding of the turbulence-chemistry interaction, and to provide validation databases for computational models.…”

Section: Introductionmentioning

confidence: 99%

Raman spectra of methane, ethylene, ethane, dimethyl ether, formaldehyde and propane for combustion applications

Magnotti

Varghese

et al. 2015

Journal of Quantitative Spectroscopy and Radiative Transfer

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Spontaneous Raman scattering measurements of temperature and major species concentration in hydrocarbon-air flames require detailed knowledge of the Raman spectra of the hydrocarbons present when fuels more complex than methane are used. Although hydrocarbon spectra have been extensively studied at room temperature, there are no data available at higher temperatures. Quantum mechanical calculations, when available are not sufficiently accurate for combustion applications. This work presents experimental measurements of spontaneous Stokes-Raman scattering spectra of methane, ethylene, ethane, dimethyl ether, formaldehyde and propane in the temperature range 300-860 K. Raman spectra from heated hydrocarbons jets have been collected with a higher resolution than is generally employed for Raman measurements in combustion applications. A set of synthetic spectra have been generated for each hydrocarbon, providing the basis for extrapolation to higher temperatures. The spectra provided here will enable simultaneous measurements of multiple hydrocarbons in flames. This capability will greatly extend the range of applicability of Raman measurements in combustion applications. In addition, the experimental spectra provide a validation dataset for quantum mechanical models.

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“…Molecular scattering techniques are capable of providing gas temperature and density information since the gas molecule properties are directly determined. Eckbreth (1996) provides the details of several molecular scattering based techniques, such as Coherent Anti-Stokes Raman Spectroscopy (CARS), spontaneous Raman and Rayleigh scattering, and Laser Induced Fluorescence (LIF), with an emphasis on their use in combustion applications. Other molecular-based techniques include laser-induced gratings (Cummings 1995, Hart et al 1999, filtered Rayleigh scattering (Boguszko and Elliott 2005), collective light scattering (Bonnet et al 1995), and molecular flow tagging techniques (Koochesfahani 1999).…”

Section: Introductionmentioning

confidence: 99%

Dynamic measurement of temperature, velocity, and density in hot jets using Rayleigh scattering

Mielke

Elam

2009

Exp Fluids

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A molecular Rayleigh scattering technique was utilized to measure time-resolved gas temperature, velocity, and density in unseeded gas flows at sampling rates up to 10 kHz. A high power continuous-wave (cw) laser beam was focused at a point in an air flow field and Rayleigh scattered light was collected and fiber-optically transmitted to a Fabry-Perot interferometer for spectral analysis. Photomultipler tubes operated in the photon counting mode allowed high frequency sampling of the total signal level and the circular interference pattern to provide time-resolved density, temperature, and velocity measurements. Mean and rms velocity and temperature, as well as power spectral density calculations, are presented for measurements in a hydrogen-combustor heated jet facility with a 50.8-mm diameter nozzle at the NASA Glenn Research Center (GRC). The Rayleigh measurements are compared with particle image velocimetry data and CFD predictions. This technique is aimed at aeronautics research related to identifying noise sources in free jets, as well as applications in supersonic and hypersonic flows where measurement of flow properties, including mass flux, is required in the presence of shocks and ionization occurrence.

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Laser Diagnostics for Temperature and Species in Unsteady Combustion

Cited by 819 publications

References 33 publications

Detailed investigation of ignition by hot gas jets

Detailed investigation of ignition by hot gas jets

Raman spectra of methane, ethylene, ethane, dimethyl ether, formaldehyde and propane for combustion applications

Dynamic measurement of temperature, velocity, and density in hot jets using Rayleigh scattering

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