Two-color absorption spectroscopy strategy for measuring the column density and path average temperature of the absorbing species in nonuniform gases

Goldenstein, Christopher S.; Schultz, Ian A.; Jeffries, Jay B.; Hanson, Ronald K.

doi:10.1364/ao.52.007950

Cited by 60 publications

(39 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, even though the flowfield has nonuniform temperature and water distributions, the flow parameters determined from TDLAS measurements in this nonuniform flow have only modest errors and are sufficiently accurate to allow useful comparisons with CFD simulations of this complex flowfield. It is worth noting that this level of accuracy is only possible because of the effective line shape measurements used here [14]. …”

Section: Comparison Of Tdlas With Cfd and Uncertainty Analysismentioning

confidence: 99%

“…To account for this effect, absorption linewidths used in the WMS analysis were fixed at values measured from direct-absorption line shapes measured in a later experiment at the same nominal facility conditions. It is shown in [14] that this method accurately accounts for the effective line shape due to nonuniform distributions of H 2 O and temperature along the LOS.…”

Section: Spectroscopic Fundamentals and Wavelength-modulation Specmentioning

confidence: 99%

“…A discussion regarding the complications and errors associated with interpretation of absorption measurements with nonuniform gas composition and temperature along the LOS is briefly discussed here; for a more complete discussion of TDLAS measurements in nonuniform flows see [14]. Here, we present estimates of the errors introduced in the following measurements by the nonuniformities along the LOS.…”

Section: Comparison Of Tdlas With Cfd and Uncertainty Analysismentioning

confidence: 99%

See 2 more Smart Citations

Diode Laser Absorption Sensor for Combustion Progress in a Model Scramjet

Schultz¹,

Goldenstein²,

Jeffries³

et al. 2014

Journal of Propulsion and Power

Self Cite

View full text Add to dashboard Cite

The development and use of a tunable diode laser absorption spectroscopy sensor for combustion product water vapor in a hydrogen-fueled model scramjet combustor are presented. A pair of absorption transitions was selected from the combination bands of water vapor near 1.4 μm exploiting telecommunications diode laser and fiber technologies. Wavelength-modulation spectroscopy with detection of the peak second-harmonic signal was used owing to its superior noise-rejection capabilities. The sensor measured temperature and H 2 O column density at two axial planes downstream of fuel injection with the absorption line-of-sight positioned at over 40 measurement locations using a translation stage system. The combustion product concentration and the gas temperature were not uniform along the line-of-sight, and the influence of these nonuniformities on the interpretation of the tunable diode laser measurements is discussed. The measurements are compared with published computational fluid dynamics simulations using two different kinetic mechanisms. Nomenclature A= integrated absorbance f = modulation frequency, Hz I t = transmitted spectral intensity, W∕cm 2 · s −1 I 0 = incident spectral intensity, W∕cm 2 · s −1 L = path length, cm P = pressure, atm R i = specific gas constant of species i, J · kg −1 · K −1 S = line strength, cm −2 ∕atm T = temperature, K ν = optical frequency, cm −1 α = absorbance γ air = air-broadening coefficient, cm −1 · atm −1 γ self = self-broadening coefficient, cm −1 · atm −1 Δν c = collisional linewidth, cm −1 ρ = bulk gas density, kg · m −3 ρ i = partial density of species i, kg · m −3 σ i = column density of species i, kg · m −2 φ = H 2 -air equivalence ratio φ ν = line shape function χ i = gas mole fraction of species i

show abstract

Section: Comparison Of Tdlas With Cfd and Uncertainty Analysismentioning

confidence: 99%

Section: Spectroscopic Fundamentals and Wavelength-modulation Specmentioning

confidence: 99%

Section: Comparison Of Tdlas With Cfd and Uncertainty Analysismentioning

confidence: 99%

See 1 more Smart Citation

Diode Laser Absorption Sensor for Combustion Progress in a Model Scramjet

Schultz¹,

Goldenstein²,

Jeffries³

et al. 2014

Journal of Propulsion and Power

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, non-uniform distributed characteristics of the combustion (117). Given two transitions with their line strengths linearly depending on the temperature over the domain of the temperature non-uniformity, Goldenstein et al developed a 2-color absorption spectroscopy strategy for measuring the column density and density-weighted path-average temperature of the absorbing species in non-uniform gases (118). The ratio of integrated absorbance areas at two transitions was given by…”

Section: Line-of-sight Measurements In Non-uniform Conditionsmentioning

confidence: 99%

Laser absorption spectroscopy for combustion diagnosis in reactive flows: A review

Liu

2018

Applied Spectroscopy Reviews

173

View full text Add to dashboard Cite

Laser absorption spectroscopy (LAS) has been rapidly developed and widely applied to combustion diagnosis in recent decades. As a costeffective tool for measuring multiple combustion parameters, LAS provides unique properties in terms of accuracy and sensitivity for understanding the reactions and kinetics in reactive flows. Line-ofsight and tomographic LAS techniques have stimulated numerous applications and been proved to be robust for in situ combustion diagnosis in uniform and non-uniform combustion fields, respectively. This review highlights the breakthroughs in the evolution of LAS techniques from the viewpoints of key principles, sensors and instrumentations developed for combustion diagnosis, with particular emphasis on a series of spatially-resolved LAS techniques with their recent applications on obtaining high-fidelity measurement results with minimal intrusion to the practical combustors. Along the way, we note some challenges and requirements for further development of the LAS-based combustion diagnosis.

show abstract

“…In the range 1200-1800 K, the two H2O transitions used by Sensor 2 allow determination of the density-weighted path-averaged temperature [24], which was then used to convert H2O column density to concentration. The linestrength/T ratio of the CO R34 and R35 transitions used by Sensor 1 changes only within 10% between 1000 and 1900 K, which enables calculation of the CO concentration directly from the integrated absorbance.…”

Section: Tdlas Sensor Setupmentioning

confidence: 99%

Real-time in situ multi-parameter TDLAS sensing in the reactor core of an entrained-flow biomass gasifier

Sepman¹,

Ögren²,

et al. 2017

Proceedings of the Combustion Institute

View full text Add to dashboard Cite

Real-time in situ multi-parameter TDLAS sensing in the reactor core of an entrained-flow biomass gasifier. Proceedings of the Combustion AbstractTunable diode laser absorption spectroscopy (TDLAS) was used to measure several important process parameters at two different locations inside the reactor of an atmospheric, air-blown 0.1 MWth biomass gasifier. Direct TDLAS at 2298 nm was employed for carbon monoxide (CO) and water vapor (H2O), calibration-free scanned wavelength modulation spectroscopy at 1398 nm for H2O and gas temperature, and direct TDLAS at 770 nm for gaseous elemental potassium, K(g), under optically thick conditions.These constitute the first in situ measurements of K(g) and temperature in a reactor core and in biomass gasification, respectively. In addition, soot volume fractions were determined at all TDLAS wavelengths, and employing fixed-wavelength laser extinction at 639 nm. Issues concerning the determination of the actual optical path length, as well as temperature and species non-uniformities along the line-of-sight are addressed. During a 2-day measurement campaign, peat and stem wood powder were first combusted at an air equivalence ratio (lambda) of 1.2 and then gasified at lambdas of 0.7, 0.6, 0.5, 0.4 and 0.35.Compared to uncorrected thermocouple measurements in the gas stream, actual average temperatures in the reactor core were significantly higher. The CO concentrations at the lower optical access port were comparable to those obtained by gas chromatography at the exhaust. In gasification mode, similar H2O values were obtained by the two different TDLAS instruments. The measured K(g) concentrations were compared to equilibrium calculations. Overall, the reaction time was found to be faster for peat than for stem wood. All sensors showed good performance even in the presence of high soot concentrations, and real-time detection was useful in resolving fast, transient behaviors, such as changes in stoichiometry.Practical implications of in-situ TDLAS monitoring on the understanding and control of gasification processes are discussed.

show abstract

Two-color absorption spectroscopy strategy for measuring the column density and path average temperature of the absorbing species in nonuniform gases

Cited by 60 publications

References 30 publications

Diode Laser Absorption Sensor for Combustion Progress in a Model Scramjet

Diode Laser Absorption Sensor for Combustion Progress in a Model Scramjet

Laser absorption spectroscopy for combustion diagnosis in reactive flows: A review

Real-time in situ multi-parameter TDLAS sensing in the reactor core of an entrained-flow biomass gasifier

Contact Info

Product

Resources

About