Emission tomography of flame radicals

Hertz, Hans M.; Faris, Gregory W.

doi:10.1364/ol.13.000351

Cited by 60 publications

(19 citation statements)

References 14 publications

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“…Its main drawback is that it is a line-of-sight method and so inherently lacks spatial resolution. Employing appropriate signal collection optics [21], however, or by using tomography methods [22] a limited degree of spatial resolution can be obtained. In addition, the passive nature of the technique limits the number of detectable species to those emitting light in some part of the optically detectable spectrum.…”

Section: Techniques Without Lasersmentioning

confidence: 99%

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Kiefer

Ewart

2011

Progress in Energy and Combustion Science

131

112

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Laser-based methods have transformed combustion diagnostics in the past few decades. The high intensity, coherence, high spectral resolution and frequency tunability available from laser radiation has provided powerful tools for studying microscopic processes and macroscopic phenomena in combustion by linear and nonlinear optical processes. This review focuses on nonlinear optical techniques based on resonant four-wave mixing for non-intrusive measurements of minor species in combustion. The importance of minor species such as reaction intermediates is outlined together with the challenges they present for detection and measurement in the hostile environments of flames, technical combustors, and engines. The limitations of conventional optical methods for such measurements are described and the particular advantages of coherent methods using nonlinear optical techniques are discussed.The basic physics underlying four-wave wave mixing processes and theoretical models for signal calculation are then presented together with a discussion of how combustion parameters may be derived from analysis of signals generated in various four-wave mixing processes. The most important four-wave mixing processes, in this context, are then reviewed:Degenerate Four-Wave Mixing (DFWM), Coherent Anti-Stokes Raman Scattering (CARS), Laser Induced Grating Spectroscopy (LIGS) and Polarization Spectroscopy (PS). In each case the fundamental physics is outlined to explain the particular properties and diagnostic advantages of each technique. The application of the methods mentioned to molecular physics studies of combustion species is then reviewed along with their application in measurement of concentration, temperature and other combustion parameters. Related nonlinear techniques and recent extensions to the ultra-fast regime are briefly reviewed. Finally practical considerations relevant to multi-dimensional and multi-species measurements, as well as applications in technical combustion systems are discussed.Keywords: nonlinear optical spectroscopy, four-wave mixing, combustion diagnostics, minor species detection, laser-induced gratings, polarization spectroscopy IntroductionEnergy from renewable sources such as solar and wind power is the goal of much current research and technological development. Combustion, however, is and is likely to remain for the foreseeable future, the most important energy source for heat, electrical power and especially for transportation. In technical combustion systems the chemical energy of fossil fuels such as coal, crude oil and natural gas is converted into heat through oxidation with oxygen from air. However, fossil fuel resources are limited and alternatives like biofuels [1] or novel technologies such as fuel cells [2] are not yet able to meet the demand. Consequently, for a sustainable use of fossil fuels it is desirable to further improve the efficiency, maintainability and reliability of existing combustion devices. Achieving such improvements depends upon an improved understanding of t...

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Section: Techniques Without Lasersmentioning

confidence: 99%

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Kiefer

Ewart

2011

Progress in Energy and Combustion Science

131

112

View full text Add to dashboard Cite

show abstract

“…Since the chemically excited radicals being measured are in steady-state, no calculation of collisional quenching is required [8], in contrast to the analysis reported in earlier work [5]. A detailed discussion of extracting number density from chemiluminescence measurements and the kinetic modeling of the CH* and OH* radicals has been published [9].…”

Section: Oh* and Ch* Measurementsmentioning

confidence: 99%

A comparison of computational and experimental lift-off heights of coflow laminar diffusion flames

Walsh

Fielding

Smooke

et al. 2005

Proceedings of the Combustion Institute

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“…By avoiding the need for (light-) sources, the complexity and the equipment requirement of CTC is greatly reduced, making the experiment much more viable. Hertz and Faris [41] first applied CT to chemiluminescence emissions in 1988, albeit in 2D and with just 3 simultaneous views. More recently Ishino and Ohiwa [42] have used CT to reconstruct the broad band (400-600 nm) chemiluminescent emission intensity of a weakly turbulent nonpremixed flame to high resolution using 40 simultaneous views from a single-shot purpose built film camera.…”

Section: Introductionmentioning

confidence: 99%

Computed Tomography of Chemiluminescence (CTC): Instantaneous 3D measurements and Phantom studies of a turbulent opposed jet flame

Floyd

Geipel

Kempf

2011

Combustion and Flame

172

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Emission tomography of flame radicals

Cited by 60 publications

References 14 publications

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

A comparison of computational and experimental lift-off heights of coflow laminar diffusion flames

Computed Tomography of Chemiluminescence (CTC): Instantaneous 3D measurements and Phantom studies of a turbulent opposed jet flame

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