Quantitative multi-line NO-LIF temperature imaging

Bessler, Wolfgang G.; Schulz, Christof

doi:10.1007/s00340-004-1421-x

Cited by 102 publications

(53 citation statements)

References 43 publications

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“…In addition, the capability of multi-line laser-induced fluorescence thermometry on NO species (NO-LIF thermometry) has also been demonstrated to measure the temperature of sooting flames (Bejaoui et al 2015;Bessler and Schulz 2004;Denisov et al 2014). In this work, temperature profiles along the flame centerline have been obtained by NO-LIF thermometry.…”

Section: Centerline Gas Temperature Distribution By No-lif Thermometrymentioning

confidence: 99%

Investigation of the size of the incandescent incipient soot particles in premixed sooting and nucleation flames of n-butane using LII, HIM, and 1 nm-SMPS

Betrancourt

Liu

Desgroux

et al. 2017

Aerosol Science and Technology

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(2017) Investigation of the size of the incandescent incipient soot particles in premixed sooting and nucleation flames of nbutane using LII, HIM, and 1 nm-SMPS, Aerosol Science and Technology, 51:8, 916-935, DOI: 10.1080/02786826.2017 Laser-induced incandescence (LII) measurements were conducted to explore the ability of LII to detect small soot particles of less than 10 nm in two sooting flat premixed flames of n-butane: a socalled nucleation flame obtained at a threshold equivalence ratio F D 1.75, in which the incipient soot particles undergo only minor soot surface growth along the flame, and a more sooting flame at F D 1.95. Size measurements were obtained by modeling the time-resolved LII signals detected using 1064 nm laser excitation. Spectrally-resolved LII signals collected in the nucleation flame display a similar blackbody-like behavior as mature soot. Soot particle temperature was determined from spectrally-resolved detection. LII modeling was conducted using parameters either relevant to those of mature soot or derived from fitting the modeled results to the experimental LII data. Particle size measurements were also carried out using (1) ex situ analysis by helium-ion microscopy (HIM) of particles sampled thermophoretically and (2) online size distribution analysis of microprobe-sampled particles using a 1 nm-SMPS. The size distributions of the incipient soot particles, found in the nucleation flame and in the early soot region of the F D 1.95 flame, derived from time-resolved LII signals are in good agreement with HIM and 1 nm-SMPS measurements and are in the range of 2-4 nm. The thermal and optical properties of incipient soot were found to be not radically different from those of mature soot commonly used in LII modeling. This explains the ability of incipient soot particles to produce continuous thermal emissions in the visible spectrum. This study demonstrates that LII is a promising in situ optical particle sizing technique that is capable of detecting incipient soot as small as about 2.5 nm and potentially 2 nm and resolving small changes in soot sizes below 10 nm.

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Section: Centerline Gas Temperature Distribution By No-lif Thermometrymentioning

confidence: 99%

Investigation of the size of the incandescent incipient soot particles in premixed sooting and nucleation flames of n-butane using LII, HIM, and 1 nm-SMPS

Betrancourt

Liu

Desgroux

et al. 2017

Aerosol Science and Technology

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“…7) at the considered temperatures, it can be concluded that the maximum temperature deviation caused by fluctuations of this magnitude for region 1 is less than ±2 %. This value is within the stated accuracy of ±2 % for multi-line NO-LIF thermometry for flames of the present type [1,10].…”

Section: Temperature / Kmentioning

confidence: 58%

“…Multi-line nitric oxide (NO)-laserinduced fluorescence (LIF) thermometry imaging enables accurate measurements of gas-phase temperature distributions in a spatial plane without the necessity of calibration [1]. The technique relies on the temperature dependence of NO LIF excitation spectra [1][2][3]. In thermal equilibrium, the temperature dependence of the population of the rotational ground state energy levels is described by the Boltzmann distribution.…”

mentioning

confidence: 99%

Effect of fluctuations on time-averaged multi-line NO-LIF thermometry measurements of the gas-phase temperature

et al. 2015

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chemistry and therefore, e.g., combustion efficiency and pollutant formation. Multi-line nitric oxide (NO)-laserinduced fluorescence (LIF) thermometry imaging enables accurate measurements of gas-phase temperature distributions in a spatial plane without the necessity of calibration [1]. The technique relies on the temperature dependence of NO LIF excitation spectra [1][2][3]. In thermal equilibrium, the temperature dependence of the population of the rotational ground state energy levels is described by the Boltzmann distribution. A laser is tuned across the vibronic transitions of the electronic A-X absorption band and the population fractions of individual rotational quantum states are probed by recording the respective LIF signal intensity with an intensified CCD camera. Excitation spectra are then extracted for each pixel from the stack of images taken for each laser wavelength position. Simulated spectra are then fitted to the experimental spectra with absolute temperature as the adjustable parameter. Spectral line broadening and background signals (e.g., scattered laser light or broad-band fluorescence) are included in the fitting routine.Multi-line techniques have demonstrated their robustness in stable low-pressure [4,5], atmospheric pressure [6], and high-pressure flames [7,8] as well as in systems with a large scattering background such as sooting flames [1] and spray systems [9,10]. In contrast to conventional two-color temperature imaging techniques (e.g., [11]), the multi-line approach has the advantage of being calibrationfree and robust against background signal as long as the shape of the excitation spectra can still be distinguished on top of the background signal and the background does not strongly vary with excitation wavelength within the investigated spectral range. Therefore, especially in highpressure flames, NO-LIF transitions must be chosen that do not interfere with LIF from hot O 2 [12]. The method, however, lacks single-shot capability because the spectra Abstract Multi-line NO laser-induced fluorescence (LIF) thermometry enables accurate gas-phase temperature imaging in combustion systems through least-squares fitting of excitation spectra. The required excitation wavelength scan takes several minutes which systematic biases the results in case of temperature fluctuations. In this work, the effect of various types (linear, Gaussian and bimodal) and amplitudes of temperature fluctuations is quantified based on simulated NO-LIF excitation spectra. Temperature fluctuations of less than ±5 % result in a negligible error of less than ±1 % in temperature for all cases. Bimodal temperature distributions have the largest effect on the determined temperature. Symmetric temperature fluctuations around 900 K have a negligible effect. At lower mean temperatures, fluctuations cause a positive bias leading to over-predicted mean temperatures, while at higher temperatures the bias is negative. The results of the theoretical analysis were applied as a guide for interpreting experimental multi-line ...

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“…7 LIF techniques like NO LIF, which are reliable temperature sensors even in the presence of background signals, are applicable only to laminar and stationary flames. 8 Besides this, different coherent techniques like degenerate four-wave mixing (DFWM), 9 polarization spectroscopy (PS) 10 and coherent anti-Stokes Raman spectroscopy (CARS) exist for temperature measurements in flames. For the application as a temperature sensor in technical combustion, CARS is the most reputed as, in the past, it has provided the best qualification with the highest accuracy.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the combustion process in an auxiliary heating system using dual‐pump CARS

Braeuer¹,

Beyrau

Weikl

et al. 2006

J Raman Spectroscopy

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A dual-pump coherent anti-Stokes Raman spectroscopy (CARS) setup was used for the simultaneous determination of temperature and oxygen/nitrogen ratio in an automotive auxiliary heating system. The auxiliary heating system was equipped with eight windows to provide four line-of-sight optical accesses at two different downstream levels. The usable laser pulse energies, which are essentially limited by the damage threshold of the glass windows, were increased by the application of an optical pulse stretcher. Measurements were performed for standard diesel fuel for full-and part-load operation as well as for the model fuel n-dodecane for full-load operation. The n-dodecane measurements can directly be compared with numerical predictions, whereas the results for diesel fuel provide information about the possibility of transfer of the n-dodecane simulations to real fuel conditions.

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Quantitative multi-line NO-LIF temperature imaging

Cited by 102 publications

References 43 publications

Investigation of the size of the incandescent incipient soot particles in premixed sooting and nucleation flames of n-butane using LII, HIM, and 1 nm-SMPS

Investigation of the size of the incandescent incipient soot particles in premixed sooting and nucleation flames of n-butane using LII, HIM, and 1 nm-SMPS

Effect of fluctuations on time-averaged multi-line NO-LIF thermometry measurements of the gas-phase temperature

Investigation of the combustion process in an auxiliary heating system using dual‐pump CARS

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