Interference-free two-photon LIF imaging of atomic hydrogen in flames using picosecond excitation

Kulatilaka, Waruna D.; Frank, Jonathan H.; Settersten, Thomas B.

doi:10.1016/j.proci.2008.06.125

Cited by 41 publications

(24 citation statements)

References 28 publications

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“…The commonly used species for PLIF are CH 2 O, OH and HCO. The LIF of atomic hydrogen H needs two-photon techniques as has been demonstrated in past studies (Kulatilaka et al, 2009;Marshall and Pitz, 2018;Mulla et al, 2016) and is also analyzed here. The values of β for this study is set to be 2.6 for CH 2 O, 0 for OH and 1.25 for HCO based on past experimental studies (Najm et al, 1998;Paul and Najm, 1998).…”

Section: Markers For Heat Releasementioning

confidence: 98%

“…The values of β for this study is set to be 2.6 for CH 2 O, 0 for OH and 1.25 for HCO based on past experimental studies (Najm et al, 1998;Paul and Najm, 1998). The value of this parameter for the atomic hydrogen is 2 (Kulatilaka et al, 2009). There are, however, some uncertainties for the β values but the results did not change unduly if slightly different values are used.…”

Section: Markers For Heat Releasementioning

confidence: 99%

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Analysis of Markers for Combustion Mode and Heat Release in MILD Combustion Using DNS Data

Doan

Swaminathan

2019

Combustion Science and Technology

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Various commonly used markers for heat release are assessed using direct numerical simulation (DNS) data for Moderate or Intense Lowoxygen Dilution (MILD) combustion to find their suitability for nonpremixed MILD combustion. The laser-induced fluorescence (LIF) signals of various markers are synthesized from the DNS data to construct their planar (PLIF) images which are compared to the heat release rate images obtained directly from the DNS data. The local OH values in heat releasing regions are observed to be very small compared to the background level coming from unreacted mixture diluted with exhaust gases. Furthermore, these values are very much smaller compared to those in burnt regions. This observation rises questions on the use of OH-PLIF for MILD combustion. However, the chemiluminescent image obtained using OH Ã is shown to correlate well with the heat release. Two scalar-based PLIF markers,, correlate well with the heat release. Flame index (FI) and chemical explosive mode analyses (CEMA) are used to identify premixed and non-premixed regions in MILD combustion. Although there is some agreement between the CEMA and FI results, large discrepancies are still observed. The schlieren images deduced from the DNS data showed that this technique can be used for a quick and qualitative identification of MILD combustion before applying expensive laser diagnostics.

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Section: Markers For Heat Releasementioning

confidence: 98%

Section: Markers For Heat Releasementioning

confidence: 99%

Analysis of Markers for Combustion Mode and Heat Release in MILD Combustion Using DNS Data

Doan

Swaminathan

2019

Combustion Science and Technology

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“…Since then, a plethora of experimental and numerical studies has emerged. These studies validated the excellent capability of TALIF to determine atomic densities in flames and plasmas [28,36,[39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54]. The concept of this method is depicted in Figure 2.…”

Section: Talif Principles Involved Theory and Experimental Requirementsmentioning

confidence: 56%

“…The recorded O-TALIF signals provided accurate measurements of O atom profiles in the flame. Kulatilaka et al [53] achieved interference-free planar (by creating a laser sheet) ps-TALIF experiments and determined the atomic hydrogen density in CH4/O2/N2 flames. The laser sheet dimensions were of 2.5 mm × 200 μm.…”

Section: Ultrafast (Ps/fs) Talifmentioning

confidence: 99%

Progresses on the Use of Two-Photon Absorption Laser Induced Fluorescence (TALIF) Diagnostics for Measuring Absolute Atomic Densities in Plasmas and Flames

Lombardi

Aubert

Duluard

et al. 2021

Plasma

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Recent developments in plasma science and technology have opened new areas of research both for fundamental purposes (e.g., description of key physical phenomena involved in laboratory plasmas) and novel applications (material synthesis, microelectronics, thin film deposition, biomedicine, environment, flow control, to name a few). With the increasing availability of advanced optical diagnostics (fast framing imaging, gas flow visualization, emission/absorption spectroscopy, etc.), a better understanding of the physicochemical processes taking place in different electrical discharges has been achieved. In this direction, the implementation of fast (ns) and ultrafast (ps and fs) lasers has been essential for the precise determination of the electron density and temperature, the axial and radial gradients of electric fields, the gas temperature, and the absolute density of ground-state reactive atoms and molecules in non-equilibrium plasmas. For those species, the use of laser-based spectroscopy has led to their in situ quantification with high temporal and spatial resolution, with excellent sensitivity. The present review is dedicated to the advances of twophoton absorption laser induced fluorescence (TALIF) techniques for the measurement of reactive species densities (particularly atoms such as N, H and O) in a wide range of pressures in plasmas and flames. The requirements for the appropriate implementation of TALIF techniques as well as their fundamental principles are presented based on representative published works. The limitations on the density determination imposed by different factors are also discussed. These may refer to the increasing pressure of the probed medium (leading to a significant collisional quenching of excited states), and other issues originating in the high instantaneous power density of the lasers used (such as photodissociation, amplified stimulated emission, and photoionization, resulting to the saturation of the optical transition of interest).

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“…Atomic hydrogen is a key intermediate species in hydrocarbon combustion due to its high reactivity and diffusivity, thus playing a major role in ignition/extinction and heat release [3,6,7]. As another example, understanding the spatial distribution of H and O atoms is critical for effective usage of biomedical plasmas in the rapidly growing area of plasma medicine [8].…”

Section: Introductionmentioning

confidence: 99%

Multi-Photon Fluorescence Imaging of Flame Species Using Femtosecond Excitation

Kulatilaka

Roy

Katta

et al. 2012

28th Aerodynamic Measurement Technology, Ground Testing, and Flight Testing Conference

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We demonstrate-for the first time-interference-free, detection of atomic hydrogen (H) in reacting flows at 1 kHz using femtosecond, two-photon-excited, laser-induced-fluorescence (fs-TPLIF) line imaging. Broadband, nearly-transform-limited, fs pulses at 205 nm efficiently populate = →→ = transition via two-photon excitation and subsequent one-dimensional fluorescence signal at 656 nm from = → = decay is imaged. Because the TPLIF signal scales as the laser irradiance squared, to produce the same fluorescence signal level, significantly lower pulse energy is required from fs-duration pulses in comparison to ns-or ps-duration pulses. The reduced laser energy virtually eliminates the single-photon-induced photodissociation of flame radicals generating additional H-atoms in the medium. In the premixed CH 4 /O 2 /N 2 flames investigated, we observed no evidence of photoionization or stimulated emission; two other processes that can further complicate the quantitative detection of H-atoms via TPLIF. Similar fs-TPLIF approach is also used for imaging O-atom and CO. Interference-free detection of O-atom and CO are also discussed. Nomenclature LIF= laser-induced-fluorescence TPLIF = two-photon-excited laser-induced-fluorescence CO = carbon monoxide VUV = vacuum ultra violet PLIF = planar laser-induced fluorescence OPA = optical parametric amplifier ICCD = intensified charge couple device

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Interference-free two-photon LIF imaging of atomic hydrogen in flames using picosecond excitation

Cited by 41 publications

References 28 publications

Analysis of Markers for Combustion Mode and Heat Release in MILD Combustion Using DNS Data

Analysis of Markers for Combustion Mode and Heat Release in MILD Combustion Using DNS Data

Progresses on the Use of Two-Photon Absorption Laser Induced Fluorescence (TALIF) Diagnostics for Measuring Absolute Atomic Densities in Plasmas and Flames

Multi-Photon Fluorescence Imaging of Flame Species Using Femtosecond Excitation

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