Thermal grating and broadband degenerate four-wave mixing spectroscopy of OH in high-pressure flames

Latzel, H.; Dreizler, Andreas; Dreier, Thomas; Heinze, Johannes; Dillmann, M.; Stricker, W.; Lloyd, G. M.; Ewart, Paul

doi:10.1007/s003400050563

Cited by 55 publications

(33 citation statements)

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“…Although the potential for using LIGS for thermometry was recognised at an early stage [175,181] initial studies focussed on elucidating the dynamics of the grating evolution and its dependence on gas dynamic parameters. The potential for measurement of temperature and pressure was realized first by Latzel et al [209] who recorded LIGS signals generated on the A The values obtained were in good agreement with independent temperature measurements using N 2 CARS and predictions from a one-dimensional flame calculation. These and similar experiments by other workers used pulsed excitation by a Nd:YAG pumped dye laser and a cw Argon ion laser as the probe.…”

Section: Concentration Measurements and Thermometry Applicationsmentioning

confidence: 62%

“…Multiplex FWM spectroscopy of OH for flame thermometry has also been reported by Lloyd et al [76]. Latzel et al [209] recorded broadband DFWM spectra in methane/air flames at elevated pressure (atmospheric to 30 bar) concluding that thermometry is possible at pressures as high as 6 bar. Beyond this pressure the experimental DFWM signals did not provide sufficient intensity levels.…”

Section: Multi-species and Multiplex Measurementsmentioning

confidence: 67%

“…A range of stable species and radicals have been detected in this way including NO [118,182], NO 2 [181,187,198,206,207], OH [175,208,209] [197], CH 3 OH [176] and C 3 H 8 [212,213] have also been detected but in combustion situations these are usually present in relatively large concentrations. Nonetheless it may be useful to consider LIGS for detection of fuel compounds as they may be present as unburned hydrocarbons in exhaust gases.…”

Section: Concentration Measurements and Thermometry Applicationsmentioning

confidence: 99%

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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: Concentration Measurements and Thermometry Applicationsmentioning

confidence: 62%

Section: Multi-species and Multiplex Measurementsmentioning

confidence: 67%

Section: Concentration Measurements and Thermometry Applicationsmentioning

confidence: 99%

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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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“…Cummings was able to derive the temperature of laboratory air from time-averaged LITA signals arising from absorption by trace amounts of NO 2 [20]. The first measurements of flame temperature using LITGS were reported by Latzel et al using OH in a high-pressure methane/air flame [24]. More recently, the high precision available from LITGS thermometry, on the order of 0.1%, has led to increased interest in the technique [25].…”

Section: Introductionmentioning

confidence: 99%

Flame thermometry using laser-induced-grating spectroscopy of nitric oxide

et al. 2018

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A systematic study of laser-induced thermal-grating scattering (LITGS) using nitric oxide as an absorbing species is presented as a means of thermometry in air-fed combustion. The relative contributions to the scattered signal from degenerate four-wave mixing, DFWM, and from laser-induced thermal-grating scattering, LITGS, are studied in the time domain for NO in N 2 buffer gas up to 4 bar, using a pulsed laser system to excite the (0,0) γ-bands of NO at 226.21 nm. LITGS signals from combustion-generated NO in a laminar, pre-mixed CH 4 /O 2 /N 2 flame on an in-house constructed slot burner were used to derive temperature values as a function of O 2 concentration and position in the flame at 1 and 2.5 bar total pressure. Temperature values consistent with the calculated adiabatic flame temperature were derived from averaged LITGS signals over 50-100 single shots at 10 Hz repetition rate in the range 1600-2400 K with a pressure-dependent uncertainty of ± 1.8% at 1 bar to ± 1.4% at 2.5 bar. Based on observed signal-to-noise ratios, the minimum detectable concentration of NO in the flame is estimated to be 80 ppm for a 5 s measurement time at 10 Hz repetition rate.

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“…In addition, the signal intensity is related to the absorber concentration and the Doppler shifts of the scattered signal give information on the bulk gas velocity. The LIGS signal, therefore, may be analysed to give information on multiple parameters simultaneously: temperature (Cummings 1994;Latzel et al 1998), pressure (Stevens and Ewart 2004;Hart et al 2007), flow velocity (Mach number) (Walker et al 1998;Kozlov 2005;Hemmerling et al 2000), and concentration of the absorbing species (Seeger et al 2006;Roshani et al 2013). A particular advantage of LIGS is the robustness and high precision of temperature measurements that results from the measuring of a frequency rather than intensity (Stevens and Ewart 2004;Williams et al 2014;Förster et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Time-resolved gas thermometry by laser-induced grating spectroscopy with a high-repetition rate laser system

et al. 2017

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flows where physical probes may prove too invasive and perturbing. Fast-response thermocouples can be used in some situations, but optical techniques are sometimes the only alternative when a non-invasive technique is required. Methods using continuous wave lasers, such as tunable diode laser absorption spectroscopy, can provide temperature data when the absorption line being probed can be scanned at high-repetition rates, but, being a line-of-sight technique, the method lacks spatial resolution (Allen 1998;Davidson et al. 1991;Hanson et al. 1977;Hanson and Davidson 2014). Techniques using pulsed lasers can be limited by the repetition rate of the lasers used-typically 10Hz-for a range of techniques including Rayleigh scattering, laser-induced fluorescence, and non-linear methods such as coherent anti-Stokes Raman scattering, CARS. High-speed CARS, using femto-second mode-locked lasers, is an attractive option, but the systems are usually complex and expensive, and require sophisticated data analysis (Eckbreth 1996;Kohse-Höinghaus and Jeffries 2002;Roy et al. 2010). Laser-induced grating spectroscopy (LIGS), also referred to as laser-induced thermal acoustics (LITA), offers an alternative method for gas dynamic measurements with somewhat simpler analysis and relatively simple laser systems.LIGS relies on the formation of a spatially periodic modulation of the complex refractive index, i.e. a grating, off which a signal beam is generated in a first-order Bragg scattering process. The transient grating is formed by crossing two beams of pulsed laser light to establish the periodic interference pattern in the region of intersection. The spatial period of this pattern is determined by the wavelength of the pump beams and the crossing angle, θ (usually small). In general, two effects contribute to the grating formation, viz. electrostriction, which is non-resonant, and resonant absorption leading Abstract Thermometry using laser-induced grating spectroscopy (LIGS) is reported using a high-repetition rate laser system, extending the technique to allow timeresolved measurements of gas dynamics. LIGS signals were generated using the second harmonic output at 532 nm of a commercially available high-repetition rate Nd:YAG laser with nitrogen dioxide as molecular seed. Measurements at rates up to 10 kHz were demonstrated under static cell conditions. Transient temperature changes of the same gas contained in a cell subjected to rapid compression by injection of gas were recorded at 1 kHz to derive the temperature evolution of the compressed gas showing temperature changes of 50 K on a time-scale of 0.1 s with a measurement precision of 1.4%. The data showed good agreement with an analytical thermodynamic model of the compression process.

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Thermal grating and broadband degenerate four-wave mixing spectroscopy of OH in high-pressure flames

Cited by 55 publications

References 1 publication

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

Flame thermometry using laser-induced-grating spectroscopy of nitric oxide

Time-resolved gas thermometry by laser-induced grating spectroscopy with a high-repetition rate laser system

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