Time-resolved measurement of the local equivalence ratio in a gaseous propane injection process using laser-induced gratings

Seeger, Thomas; Kiefer, Johannes; Weikl, Markus C.; Leipertz, Alfred; Kozlov,

doi:10.1364/oe.14.012994

Cited by 22 publications

(26 citation statements)

References 21 publications

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“…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%

“…By additionally applying Raman spectroscopy Weikl et al [286] simultaneously determined mixture composition and gas temperature in gaseous and liquid propane injection systems. In the same propane gas injection process Seeger et al [212,213] used laser-induced gratings to measure the local equivalence ratio as a function of time after the start of injection. At high fuel concentration the grating oscillation period was utilized while at low propane concentration the ratio between electrostrictive and thermal gratings yielded results with good accuracy.…”

Section: Multi-species and Multiplex Measurementsmentioning

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

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129

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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: 99%

Section: Multi-species and Multiplex Measurementsmentioning

confidence: 99%

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Kiefer

Ewart

2011

Progress in Energy and Combustion Science

Self Cite

129

112

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“…The LIGS signal is very rich in information and can provide measurements of the temperature, 168 Compared to CARS, laser-induced grating methods have been applied to combustion-related systems to a very limited extent. Seeger et al 170,177 measured the local equivalence ratio as a function of time after the start of injection in a propane gas injection process. At high fuel concentration, the grating oscillation period was utilized to derive composition information, while at low propane concentration the ratio between electrostrictive and thermal signal contributions was the measure of choice.…”

Section: Laser-induced Grating Scattering (Ligs)mentioning

confidence: 99%

Advanced Laser-Based Techniques for Gas-Phase Diagnostics in Combustion and Aerospace Engineering

Ehn

Zhu

et al. 2017

Appl Spectrosc

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Gaining information of species, temperature, and velocity distributions in turbulent combustion and high-speed reactive flows is challenging, particularly for conducting measurements without influencing the experimental object itself. The use of optical and spectroscopic techniques, and in particular laser-based diagnostics, has shown outstanding abilities for performing non-intrusive in situ diagnostics. The development of instrumentation, such as robust lasers with high pulse energy, ultra-short pulse duration, and high repetition rate along with digitized cameras exhibiting high sensitivity, large dynamic range, and frame rates on the order of MHz, has opened up for temporally and spatially resolved volumetric measurements of extreme dynamics and complexities. The aim of this article is to present selected important laser-based techniques for gas-phase diagnostics focusing on their applications in combustion and aerospace engineering. Applicable laser-based techniques for investigations of turbulent flows and combustion such as planar laser-induced fluorescence, Raman and Rayleigh scattering, coherent anti-Stokes Raman scattering, laser-induced grating scattering, particle image velocimetry, laser Doppler anemometry, and tomographic imaging are reviewed and described with some background physics. In addition, demands on instrumentation are further discussed to give insight in the possibilities that are offered by laser flow diagnostics.

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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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Time-resolved measurement of the local equivalence ratio in a gaseous propane injection process using laser-induced gratings

Cited by 22 publications

References 21 publications

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

Advanced Laser-Based Techniques for Gas-Phase Diagnostics in Combustion and Aerospace Engineering

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

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