High-repetition-rate combustion thermometry with two-line atomic fluorescence excited by diode lasers

Chrystie, Robin S. M.; Burns, Iain S.; Hult, Johan; Kaminski, Clemens F.

doi:10.1364/ol.34.002492

Cited by 22 publications

(15 citation statements)

References 11 publications

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“…An established technique that has, in recent times, received increased attention from the combustion research field, as it has the possibility to provide measurements with 278 Page 2 of 10 flames [6,[17][18][19], although, at the expense of time-averaged measurements due to the lower laser power. The advantage of using diode lasers is that they offer better control of the excitation wavelength and more stable power output resulting in better accuracy as well as enabling simultaneous path-integrated concentration measurements.…”

Section: Introductionmentioning

confidence: 99%

Diode laser-based thermometry using two-line atomic fluorescence of indium and gallium

et al. 2017

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the requirements listed above, is two-line atomic fluorescence (TLAF) [4][5][6]. TLAF is a laser-based ratiometric technique, in which the temperature-dependent population of two lower lying electronic states, of a seeded atom, is probed by laser excitation and the ratio of the resulting fluorescence is correlated with the temperature of the gas. TLAF offers several beneficial features for temperature measurements in reactive flows. Firstly, no a priori knowledge of the combustion environment is necessary as the technique is independent of quenching due to the excitation to a common upper state [7]. Secondly, the use of an atomic species as temperature marker offers advantages such as providing high transition probabilities yielding strong fluorescence signals as well as being free from errors related to vibrational and rotational energy transfer existing in molecules [8,9]. Thirdly, TLAF also has the possibility for thermometry measurements in sooting and particulate-laden flames as the detection wavelength can be shifted from the excitation wavelength [10,11]. The disadvantage of TLAF is that an atomic species, not normally present in the flame, has to be introduced which may add complexities to the experimental set-up.Two-line atomic fluorescence has been developed in steps where the first theoretical ground work was conducted by Alkemade [7] and experimentally demonstrated shortly thereafter using atomic lamps [12,13]. With the advent of suitable lasers, TLAF became a tool for temperature measurements with imaging capabilities in non-steady environments [4,10,11,[14][15][16]. Recently, TLAF measurement has been extended from the linear regime to non-linear regime by Medwell et al. [4] and to the saturation regime by Manteghi et al. [14] in an attempt to maximize the fluorescence signal for instantaneous temperature measurements. With the improvement in regards to available power and wavelengths of diode lasers, TLAF measurements using diode lasers have been shown to give accurate temperatures in both low-pressure and atmospheric Abstract A robust and relatively compact calibration-free thermometric technique using diode lasers two-line atomic fluorescence (TLAF) for reactive flows at atmospheric pressures is investigated. TLAF temperature measurements were conducted using indium and, for the first time, gallium atoms as temperature markers. The temperature was measured in a multi-jet burner running methane/air flames providing variable temperatures ranging from 1600 to 2000 K. Indium and gallium were found to provide a similar accuracy of ~ 2.7% and precision of ~ 1% over the measured temperature range. The reliability of the TLAF thermometry was further tested by performing simultaneous rotational CARS measurements in the same experiments.

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Section: Introductionmentioning

confidence: 99%

Diode laser-based thermometry using two-line atomic fluorescence of indium and gallium

et al. 2017

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“…Temporally-resolved in situ measurements of temperature and species [1][2][3][4] are essential to unveiling the transient physics of combustion processes. Applications benefiting from high time resolution include internal combustion engines (ICEs), pulsed detonation engines (PDEs), emerging deflagration-todetonation technology (DDT), supersonic combustion ramjet and shock tube research.…”

Section: Introductionmentioning

confidence: 99%

“…Applications benefiting from high time resolution include internal combustion engines (ICEs), pulsed detonation engines (PDEs), emerging deflagration-todetonation technology (DDT), supersonic combustion ramjet and shock tube research. Conventionally, fast sensors based on absorption spectroscopy use narrowband lasers fixed at a specific wavelength running in the cw mode [3,5]. This strategy is simple to implement and has a digital repetition rate typically limited by the detection system's sampling rate (~ MS/s).…”

Section: Introductionmentioning

confidence: 99%

Towards simultaneous calibration-free and ultra-fast sensing of temperature and species in the intrapulse mode

Chrystie

Nasir

Farooq

2015

Proceedings of the Combustion Institute

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Towards simultaneous calibration-free and ultra-fast sensing of temperature and species in the intrapulse mode KAUST Repository Abstract:We report on exploiting the down-chirp phenomenon seen in quantum cascade lasers (QCLs), when modulated with long pulses, for the purpose of performing calibration-free and temporally resolved measurements. Intrapulse spectra of a native species (e.g. H 2 O), common to combustion environments, were generated near λ=7.62 µm at repetition rates as high as 3.125 MHz. Two-line absorption spectroscopy was employed to infer calibration-free temperature from the chirp-induced intrapulse spectra. In this study, such temperature measurements were limited to rates of 250 kHz due to spectral distortion at higher repetition rates. We demonstrate the ease at which accurate temperatures and H 2 O compositions can be achieved using simple and compact QCLs operated in the intrapulse mode. The sensor is also applicable to other species, and has the potential to be integrated into commercial technologies.

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“…Here, we showcase uncluttered, spectrally-pure Voigt profile fitting with accompanying peak SNRs of 150, resulting in a typical temperature precision of 0.9% (1σ) at an effective time-resolution of 1.0 MHz. Our sensor is applicable to other species, and can be integrated into commercial technologies.Accurate, precise, and noninvasive sensing obtainable by laser diagnostics is invaluable to applications such as chemistry, environmental monitoring, and combustion research [1][2][3][4]. Time-resolved diagnostics are essential to study transient phenomena, for example, as seen in explosions, internal combustion engines, gas turbines, and shock tubes.…”

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confidence: 99%

Ultra-fast and calibration-free temperature sensing in the intrapulse mode

2014

Self Cite

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Ultra-fast and calibration-free temperature sensing in the intrapulse mode A simultaneously time-resolved and calibration-free sensor has been demonstrated to measure temperature at the nanosecond timescale at repetition rates of 1.0 MHz. The sensor benefits from relying on a single laser, is intuitive and straightforward to implement, and sweeps across spectral ranges in excess of 1 cm -1 . The sensor can fully resolve rovibrational features of the CO molecule, native to combustion environments, in the mid-infrared range near λ = 4.85 µm at typical combustion temperatures (800-2500 K) and pressures (1-3 atm). All of this is possible through the exploitation of chirp in a quantum cascade laser, operating at a duty cycle of 50%, and by using high bandwidth (500 MHz) photodetection. Here, we showcase uncluttered, spectrally-pure Voigt profile fitting with accompanying peak SNRs of 150, resulting in a typical temperature precision of 0.9% (1σ) at an effective time-resolution of 1.0 MHz. Our sensor is applicable to other species, and can be integrated into commercial technologies. KAUST Repository

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High-repetition-rate combustion thermometry with two-line atomic fluorescence excited by diode lasers

Cited by 22 publications

References 11 publications

Diode laser-based thermometry using two-line atomic fluorescence of indium and gallium

Diode laser-based thermometry using two-line atomic fluorescence of indium and gallium

Towards simultaneous calibration-free and ultra-fast sensing of temperature and species in the intrapulse mode

Ultra-fast and calibration-free temperature sensing in the intrapulse mode

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