Bibliografias temáticas / Laser-Induced incandescence/fluorescence

Literatura científica selecionada sobre o tema "Laser-Induced incandescence/fluorescence"

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Publicado: 22 de junho de 2024

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Artigos de revistas sobre o assunto "Laser-Induced incandescence/fluorescence":

Vander Wal, Randall L. "Investigation of soot precursor carbonization using laser-induced fluorescence and laser-induced incandescence". Combustion and Flame 110, n.º 1-2 (julho de 1997): 281–84. http://dx.doi.org/10.1016/s0010-2180(97)00072-2.

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Meyer, Terrence R., Sukesh Roy, Vincent M. Belovich, Edwin Corporan e James R. Gord. "Simultaneous planar laser-induced incandescence, OH planar laser-induced fluorescence, and droplet Mie scattering in swirl-stabilized spray flames". Applied Optics 44, n.º 3 (20 de janeiro de 2005): 445. http://dx.doi.org/10.1364/ao.44.000445.

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Hayashida, Kazuhiro, Kenji Amagai, Keiji Satoh e Masataka Arai. "Experimental Analysis of Soot Formation in Sooting Diffusion Flame by Using Laser-Induced Emissions". Journal of Engineering for Gas Turbines and Power 128, n.º 2 (9 de fevereiro de 2005): 241–46. http://dx.doi.org/10.1115/1.2056536.

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Two-dimensional images of OH fluorescence, polycyclic aromatic hydrocarbons (PAHs) fluorescence, and laser-induced incandescence (LII) from soot were measured in a sooting diffusion flame. To obtain an accurate OH fluorescence image, two images were taken with the laser wavelength tuned to (“on”) and away from (“off”) the OH absorption line. An accurate OH fluorescence image was obtained by subtracting the off-resonance image from the on-resonance image. For the PAH fluorescence and LII measurements, temporally resolved measurements were used to obtain the individual images; the LII image was obtained by detecting the LII signal after the PAH fluorescence radiation had stopped and the PAH fluorescence image was obtained by subtracting the LII image from the simultaneous image of PAH fluorescence and LII. Based on the obtained images, the relative location of OH, PAH, and soot in the flame was discussed in detail. To investigate the PAH size distribution in a sooting flame using LIF, an estimation strategy for PAH size is proposed. Emission spectra were measured at several heights in the flame using a spectrograph. Since the emission wavelength of PAH fluorescence shifts toward longer wavelengths with increasing PAH size, the main PAH components in the emission spectra could be estimated. The results suggest that PAH grows and the type of PAH changes as the soot inception region was approached. Near the soot inception region, we estimated that the PAHs, which have over 16 carbon atoms, mainly constituted the emission spectrum.

He, Xu, Xiao Ma, Fujia Wu e Jianxin Wang. "MD2-3: Investigation of Soot Formation in the Oxygenated Fuels Flame by Laser Induced Fluorescence and Incandescence(MD: Measurement and Diagnostics,General Session Papers)". Proceedings of the International symposium on diagnostics and modeling of combustion in internal combustion engines 2008.7 (2008): 577–84. http://dx.doi.org/10.1299/jmsesdm.2008.7.577.

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Hayashi, Jun, Nozomu Hashimoto, Noriaki Nakatsuka, Kazuki Tainaka, Hirofumi Tsuji, Kenji Tanno, Hiroaki Watanabe, Hisao Makino e Fumiteru Akamatsu. "Simultaneous imaging of Mie scattering, PAHs laser induced fluorescence and soot laser induced incandescence to a lab-scale turbulent jet pulverized coal flame". Proceedings of the Combustion Institute 37, n.º 3 (2019): 3045–52. http://dx.doi.org/10.1016/j.proci.2018.09.028.

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Kosaka, H., T. Aizawa e T. Kamimoto. "Two-dimensional imaging of ignition and soot formation processes in a diesel flame". International Journal of Engine Research 6, n.º 1 (1 de fevereiro de 2005): 21–42. http://dx.doi.org/10.1243/146808705x7347.

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The processes of ignition and formation of soot precursor and soot particles in a diesel spray flame achieved in a rapid compression machine (RCM) were imaged two-dimensionally using the laser sheet techniques. For the two-dimensional imaging of time and of location where ignition first occurs in a diesel spray, planar laser-induced fluorescence (PLIF) of formaldehyde was applied to a diesel spray in an RCM. Formaldehyde has been hypothesized to be one of the stable intermediate species marking the start of oxidation reactions in a transient spray under compression ignition conditions. In this study, the laser-induced fluorescence (LIF) images of the formaldehyde formed in a diesel fuel spray during the ignition process have been obtained by exciting formaldehyde with the third harmonic of a neodymium-doped yttrium aluminium garnet (Nd:YAG) laser. The LIF images of formaldehyde in a spray revealed that the time when the first fluorescence is detected is almost identical with the time when the total heat release due to low-temperature oxidation reactions equals the heat absorption by fuel vaporization in the spray. The formaldehyde level rose steadily until the high-temperature reaction phase of diesel spray ignition. At the start of this ‘hot-ignition’ phase, the formaldehyde concentration fell rapidly, thus signalling the end of the low-temperature ignition phase. Increases in the initial ambient gas temperatures advanced the hot-ignition starting time. The first hot ignition occurred in the periphery of spray head at initial ambient gas temperatures between 580 and 660 K. When the ambient gas temperature was increased to 790 K, the position of the first ignition moved to the central region of the spray head. For the investigation of soot formation processes in a diesel spray flame, simultaneous imaging of the soot precursor and soot particles in a transient spray flame in an RCM was conducted by PLIF and by planar laser-induced incandescence (PLII) techniques. The third harmonic (355 nm) and the fundamental (1064 nm) laser pulses from an Nd:YAG laser, between which a delay of 44 ns was imposed by 13.3 m of optical path difference, were used to excite LIF from the soot precursor and laser-induced incandescence (LII) from soot particles in the spray flame. The LIF and the LII were separately imaged by two image-intensified charge-coupled device cameras with identical detection wavelengths of 400 nm and bandwidths of 80 nm. The LIF from the soot precursor was mainly located in the central region of the spray flame between 40 and 55 mm (between 270 and 370 times the nozzle orifice diameter d°) from the nozzle orifice. The LII from soot particles was observed to surround the soot precursor LIF region and to extend downstream. The first appearance of the LIF from the soot precursor in the spray flame preceded the appearance of the LII from soot particles. The intensity of the LIF from the soot precursor reached its maximum immediately after rich premixed combustion. In contrast, the intensity of the LII from soot particles increased gradually and reached its maximum after the end of injection. Measured LIF spectra, of the soot precursor in the spray flame, were very broad with the peak between 430 and 460 nm.

Chorey, Devashish, Prasad Boggavarapu, Devendra Deshmukh, Ravikrishna Rayavarapu e Yogeshwar Nath Mishra. "Comparison between Different Optical Configurations of Active-FRAME Setup in Multispectral Imaging of Flames". Photonics 11, n.º 2 (4 de fevereiro de 2024): 144. http://dx.doi.org/10.3390/photonics11020144.

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Snapshot multispectral imaging of chemical species in the flame is essential for improved understanding of the combustion process. In this article, we investigate the different configurations of a structured laser sheet-based multispectral imaging approach called the Frequency Recognition Algorithm for Multiple Exposures (FRAME). Using FRAME, a snapshot of Laser-Induced Fluorescence (LIF) of Polycyclic Aromatic Hydrocarbons (PAH) excited by 283.5 nm laser and Laser-Induced Incandescence (LII) of soot particles excited by 532 nm laser are acquired simultaneously on a single FRAME image. A laminar diffusion flame of acetylene produced by a Gülder burner is used for the experiments. The standard FRAME approach is based on creating two spatially modulated laser sheets and arranging them in a cross-patterned configuration (X). However, the effect of using different configurations (angles) of the two laser sheets on the multispectral planar imaging of the flame has not yet been studied. Therefore, we have compared the FRAME approach in four different configurations while keeping the same flame conditions. First, we have compared the relation between laser fluence and LII signals with and without spatial modulation of the 532 nm laser sheet and found that both detections follow the same curve. When comparing the maps of flame species reconstructed from the standard FRAME configuration and other configurations, there are some dissimilarities. These differences are attributed to minor changes in the imaging plane, optical alignment, laser path length, different modulation frequencies of the laser sheet, laser extinction, laser fluence, etc.

Aizawa, T., e H. Kosaka. "Investigation of the Early Soot Formation Process in a Transient Spray Flame Via Spectral Measurements of Laser-Induced Emissions". International Journal of Engine Research 7, n.º 2 (1 de abril de 2006): 93–101. http://dx.doi.org/10.1243/146808705x60825.

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In order to investigate the early soot formation process in a diesel spray flame, two-dimensional imaging and spectral measurements of laser-induced emission from soot precursors and soot particles in a transient spray flame achieved in a rapid compression machine (2.8 MPa, 710 K) were conducted. The 3rd harmonic (355 nm) and 4th harmonic (266 nm) Nd: YAG (neodymium-doped yttrium aluminium garnet) laser pulses were used as the light source for laser-induced fluorescence (LIF) from soot precursors and laser-induced incandescence (LII) from soot particles in the spray flame. The two-dimensional imaging covered an area between 30 and 55 mm downstream from the nozzle orifice. The results of two-dimensional imaging showed that strong laser-induced emission excited at 266 nm appears only on the laser incident side of the spray flame, in contrast to an entire cross-sectional distribution of the emission excited at 355 nm, indicating that 266 nm-excited emitters are stronger absorbers and more abundant than 355 nm-excited emitters in the spray flame. The spectral measurements were conducted at three different positions, 35, 45, and 55 mm downstream from the nozzle orifice, along the central axis of the spray, where LIF from soot precursors was observed in a previous two-dimensional imaging study. The spectra measured in upstream positions showed that broad emission peaked at around 400–500 nm, which is attributable to LIF from polycyclic aromatic hydrocarbons (PAHs). The spectra measured in downstream positions appeared very much like grey-body emission from soot particles.

SATOH, Keiji, Kazuhiro HAYASHIDA, Kenji AMAGAI e Masataka ARAI. "Laser Measurement of Polycyclic Aromatic Hydrocarbons in the Flame (1st Report, Separation of Laser-Induced Fluorescence and Incandescence by Time-Resolved Measurement)". Transactions of the Japan Society of Mechanical Engineers Series B 70, n.º 692 (2004): 1051–57. http://dx.doi.org/10.1299/kikaib.70.1051.

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AIZAWA, Tetsuya, Hidenori KOSAKA e Yukio MATSUI. "2-D Imaging of Soot Formation Process in a Transient Spray Flame by Laser-induced Fluorescence and Incandescence Techniques". Proceedings of the JSME annual meeting 2002.4 (2002): 95–96. http://dx.doi.org/10.1299/jsmemecjo.2002.4.0_95.

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Mais fontes

Teses / dissertações sobre o assunto "Laser-Induced incandescence/fluorescence":

Dunn, Jaclyn. "Investigation of premixed sooting flames by combined laser induced incandescence and laser induced fluorescence". Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=23116.

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This study applies the techniques of laser induced incandescence (LII) and laser induced fluorescence (LIF) to investigate laminar sooting flames of premixed ethylene air. The approach involves using three different excitation wavelengths, together with temporally and spectrally resolved detection, generating a rich dataset concerning the formation of soot and polycyclic aromatic hydrocarbons (PAHs). Both prompt and delayed detection are used to perform LII when exciting with short wavelengths, both with issues involved. Delayed detection gives an underestimation of soot volume fraction at low heights in the flame, as a result of particle size effects. Prompt detection gives overestimation of soot volume fraction due to fluorescence in the measurement volume. It is shown that care must be taken with either method and through evaluation of the associated errors this study shows delayed detection provides a more accurate measure of soot volume fraction. The ability to obtain the flu orescence signals over a range of heights above burner and stoichiometries is demonstrated. The approach relies on heating the soot particles equivalently with three excitation wavelengths so the LII contribution to the signals can be subtracted, leaving only fluorescence. Fluorescence profiles obtained show similar features to those seen in the literature for invasive measurements, including a reduction in the fluorescence signal generated by 283 nm excitation at intermediate heights above the burner surface followed by a re-increase. Although the data do not allow species-selective measurements of PAHs, these in-situ measurements allow inferences to be drawn about changing concentration of different size classes of these precursors to soot formation. Finally the method of obtaining subtracting the LII contribution to signals was used to obtain fluorescence spectra both for 283 nm and 532 nm excitation. This showed the possibility that fluorescence can yield useful information that it is otherwise impossible to obtain in-situ under sooting conditions.

Bartos, Daniel Ambrose. "Detection and Characterisation of Combustion Formed Nanoparticles Using Time-Resolved Laser-Induced Emission". Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/18880.

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This thesis provides an improved characterisation of the evolution of soot nanoparticles in laminar and turbulent flames with a particular focus on the transition from nucleation to solid particles where intermediate structures occur. Laser light at 266 nm is primarily used for Laser-Induced Fluorescence (LIF) measurements as a means to detect and characterise incipient soot nanostructures that retain molecular qualities. These species have a size in the order of a few nanometres and do not absorb light at longer visible and infrared (IR) wavelengths. In addition, the 266 nm laser is used for Elastic Light Scattering and Laser-Induced Incandescence that prevail where larger solid particles are present. A 1064 nm laser, on the other hand, is used to exclusively excite solid soot particles that do absorb in the IR and preferentially incandesce. The combination of these Laser-induced-Emissions (LIE) is used to track the presence and character of both soot and soot precursor nanostructures. A key feature of these measurements is the ability to track the temporal decay of LIEs. Measurements taken in different combustion conditions (premixed, diffusion and turbulent) highlight different behaviours and properties of combustion formed particles. In all cases, the decay time of the majority of LIF signals is found to be much longer than that expected for molecules present with these flames at the same temperature, yet much shorter and spectrally different than that of soot particles, as is expected from semi-rigid structures. In some cases an obvious transition from smaller aromatic species to larger more rigid nanostructures is inferred from redshifted spectra downstream and longer fluorescent decay times. Collectively, these findings confirm the hybrid nature of nanostructures (semi-solid structure retaining molecular qualities) that dominate the early evolution of soot and highlight the multiple pathways in which soot precursor nanostructures initiate and evolve.

Fuentes, Andres. "Interactions between the reaction zone and soot field in a laminar boundary layer type diffusion flame". Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/1765.

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The concurrent spreading of a boundary layer type diffusion flame is studied. The impossibility of obtaining a low velocity laminar flow without any perturbation induced by buoyancy has lead to the development of an experimental apparatus for use in micro-gravity facilities. Based on previous experimental observations, an original numerical approach has been developed showing, first the dominating role of the radiative heat transfer on the structure of the flame and second the major role of the soot on the extinction phenomenon at the flame trailing edge. The influence of the forced flow velocity, the fuel injection velocity and oxygen concentration on the geometry of the flame has been examined by imaging of CH* and OH* radicals spontaneous emission. Laser-Induced Incandescence (LII) is used to determine the soot field concentration in the flame. The soot formation has been studied by Laser Induced Fluorescence (LIF) of Polycyclic Aromatic Hydrocarbons (PAHs). The interaction between the reaction zone and the field of soot formation/oxidation is taken into account to analyze the flame length. These results can be used as the experimental input data for a future complete validation of numerical model simulating the soot formation and oxidation in this kind of flame.

Dufitumukiza, Jean Pierre. "Développement des techniques optiques pour la caractérisation in-situ de la suie dans des foyers de combustion à haute pression". Electronic Thesis or Diss., Université de Lille (2022-....), 2023. https://pepite-depot.univ-lille.fr/ToutIDP/EDSMRE/2023/2023ULILR010.pdf.

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L'augmentation du trafic aérien pousse la recherche sur la combustion à obtenir une compréhension détaillée des processus physiques et chimiques qui se produisent dans le moteur de l'avion ; les principaux objectifs sont 1) d'améliorer le processus de combustion et 2) de réduire les émissions gazeuses et particulaires. Une solution au premier problème réside dans la combustion à une pression et une température plus élevées, mais cela peut avoir un impact sur le second problème, notamment en ce qui concerne la production de suie et les émissions de NOx. Pour trouver une solution, il est nécessaire de développer des outils expérimentaux appliqués dans des conditions de combustion représentatives de celles rencontrées dans les moteurs d'avion afin de capturer les phénomènes complexes se produisant à l'intérieur de ces moteurs. Pour ce faire, un banc d'essai aéronautique semi-industriel équipé de diagnostics optiques adaptés mis en œuvre/disponible à l'ONERA Palaiseau permet d'entrevoir des informations sur ces processus de combustion. En conséquence, cette recherche vise à développer et à mettre en œuvre des techniques optiques pour caractériser les particules de suie dans les chambres de combustion des moteurs aéronautiques. L'incandescence induite par laser (LII) est la principale technique sur laquelle portent les efforts. Cette technique est basée sur le modèle de rayonnement de la loi de Planck. La technique LII est utilisée en raison de sa grande sensibilité pour la détection de la fraction volumique de la suie et de sa flexibilité pour sa mise en œuvre dans diverses configurations optiques. En outre, le couplage de la technique LII avec d'autres techniques optiques présente un grand intérêt pour la compréhension des mécanismes et des paramètres conduisant à la formation de la suie. Premièrement, la fluorescence induite par laser (LIF) est ajoutée comme technique complémentaire pour détecter les précurseurs de suie connus sous le nom d'hydrocarbures aromatiques polycycliques (HAP). Deuxièmement, la diffusion de la lumière fournit des informations sur la distribution des gouttelettes de combustible liquide imbrûlées et des particules de suie à l'intérieur de la chambre de combustion. Troisièmement, la chimiluminescence OH* montre la zone de réaction et le dégagement de chaleur. Enfin, le transport des HAPs et de la suie ou les interactions avec le champ d'écoulement sont abordés via la vélocimétrie par image de particules (PIV)
The growth of air traffic urges combustion research to get a detailed understanding of the physical and chemical processes occurring in the aircraft engine; the main objectives are 1) to improve the combustion process and 2) to lower gaseous and particulate emissions. A solution to the first issue lies in the combustion at higher pressure and temperature, but this can impact the second issue, particularly concerning the production of soot and NOx emissions. To find a solution, it is necessary to develop experimental tools applied in representative combustion conditions relative to those encountered in aircraft engines in order to capture complex phenomena occurring inside these engines. To do this, a semi-industrial aeronautical test rig equipped with suitable optical diagnostics implemented/available at ONERA Palaiseau offers a glimpse of information into these combustion processes. As a result, this research aims to develop and implement optical techniques for characterizing soot particles in aeronautical engine-relevant combustors. Laser-Induced Incandescence (LII) is the primary technique on which efforts are directed. This technique is based on Planck's law radiation model. LII technique is used due to its high sensitivity for detecting the soot volume fraction and flexibility for its implementation in various optical configurations. In addition, the coupling of LII with other optical techniques presents a high interest in understanding the mechanisms and parameters leading to soot formation. First, Laser-Induced Fluorescence (LIF) is added as a complementary technique to detect soot precursors known as Polycyclic-Aromatic Hydrocarbons (PAHs). Secondly, light scattering provides information on the distribution of unburnt liquid fuel droplets and possible soot particle localization inside the combustor. Thirdly, OH* chemiluminescence illustrates the reaction zone and heat release. Finally, the PAHs and soot transportation or interactions with the flow field are tackled via particle image velocimetry (PIV)

Livros sobre o assunto "Laser-Induced incandescence/fluorescence":

United States. National Aeronautics and Space Administration., ed. Soot precursor material: Visualization via simultaneous LIF-LII and characterization via TEM. [Washington, D.C: National Aeronautics and Space Administration, 1996.

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Trabalhos de conferências sobre o assunto "Laser-Induced incandescence/fluorescence":

Nakagawa, Hiroshi, Hiroyuki Endo, Yoshihiro Deguchi, Matsuhei Noda, Hiroshi Oikawa e Taizo Shimada. "OH, NO, and Soot Measurement in Diesel Spray Flames Using Laser Induced Fluorescence and Laser Induced Incandescence". In Laser Applications to Chemical and Environmental Analysis. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/lacea.1996.lthc.7.

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Although the time-space mechanism of NOx formation in diesel injection combustion in high temperature and pressure has conventionally been pursued by the sampling method and so forth(1), the cause-effect relationship on its formation factors still remains to be more accurately clarified. In our present research, NO, OH and soot in diesel fuel flames from a single injection in high temperature and pressure were measured using a motoring compressed injection test system by applying laser induced fluorescence (LIF)(2)(3)(4)(5)(6) and laser induced incandescence (LU)(6)(7), both of which can provide unperturbed measurements necessary for clarifying formation characteristics of harmful exhaust substances from diesel fuel flames in high pressure.

Cruz Villanueva, Juan Jose, Luís Fernando Figueira da Silva e Andrés Fuentes. "EXPERIMENTAL STUDY OF LAMINAR NON PREMIXED ETHYLENE/AIR FLAMES USING LASER INDUCED INCANDESCENCE AND FLUORESCENCE". In 24th ABCM International Congress of Mechanical Engineering. ABCM, 2017. http://dx.doi.org/10.26678/abcm.cobem2017.cob17-1593.

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Aizawa, Tetsuya, Hidenori Kosaka e Yukio Matsui. "2-D Imaging of Soot Formation Process in a Transient Spray Flame by Laser-induced Fluorescence and Incandescence Techniques". In SAE Powertrain & Fluid Systems Conference & Exhibition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2002. http://dx.doi.org/10.4271/2002-01-2669.

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Meyer, Terrence R., Sukesh Roy, Sivaram P. Gogineni, Vincent M. Belovich, Edwin Corporan e James R. Gord. "OH PLIF and Soot Volume Fraction Imaging in the Reaction Zone of a Liquid-Fueled Model Gas-Turbine Combustor". In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-54318.

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Simultaneous measurements of OH planar laser-induced fluorescence (PLIF) and laser-induced incandescence (LII) are used to characterize the flame structure and soot formation process in the reaction zone of a swirl-stabilized, JP-8-fueled model gas-turbine combustor. Studies are performed at atmospheric pressure with heated inlet air and primary-zone equivalence ratios from 0.55 to 1.3. At low equivalence ratios (φ < 0.9), large-scale structures entrain rich pockets of fuel and air deep into the flame layer; at higher equivalence ratios, these pockets grow in size and prominence, escape the OH-oxidation zone, and serve as sites for soot inception. Data are used to visualize soot development as well as to qualitatively track changes in overall soot volume fraction as a function of fuel-air ratio and fuel composition. The utility of the OH-PLIF and LII measurement system for test rig diagnostics is further demonstrated for the study of soot-mitigating additives.

Kearney, Sean P., Thomas W. Grasser e Steven J. Beresh. "Filtered Rayleigh Scattering Thermometry in a Premixed Sooting Flame". In ASME 2004 Heat Transfer/Fluids Engineering Summer Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ht-fed2004-56894.

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Filtered Rayleigh Scattering (FRS) is demonstrated in a premixed, sooting ethylene-air flame. In sooting flames, traditional laser-based temperature-imaging techniques such linear (unfiltered) Rayleigh scatting (LRS) and planar laser-induced fluorescence (PLIF) are rendered intractable due to intense elastic scattering interferences from in-flame soot. FRS partially overcomes this limitation by utilizing a molecular iodine filter in conjunction with an injection-seeded Nd:YAG laser, where the seeded laser output is tuned to line center of a strong iodine absorption transition. A significant portion of the Doppler-broadened molecular Rayleigh signal is then passed while intense soot scattering at the laser line is strongly absorbed. In this paper, we demonstrate the feasibility of FRS for sooting flame thermometry using a premixed, ethylene-air flat flame. We present filtered and unfiltered laser light-scattering images, FRS temperature data, and laser-induced incandescence (LII) measurements of soot volume fraction for fuel-air equivalence ratios of φ = 2.19 and 2.24. FRS-measured product temperatures for these flames are nominally 1500 K. The FRS temperature and image data are discussed in the context of the soot LII results and a preliminary estimate of the upper sooting limit for our FRS system of order 0.1 ppm volume fraction is obtained.

Perrier, Aurélien, Andrei-Silviu Milea, Marcos Caceres, Alexis Vandel, Gilles Godard, Alain Cayre, Félix Collin-Bastiani, Gilles Cabot e Frédéric Grisch. "Soot Formation and Flame Characterization in a Swirl Kerosene Spray Rich Burn-Quench-Lean Burner at Elevated Pressure". In ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gt2023-103642.

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Abstract Swirl-stabilized, turbulent, non-premixed kerosene-air flames were studied experimentally in an RQL (Rich burn/Quick-quench/Lean-burn) model combustor equipped with large optical accesses. The goal of these studies was to characterize the flame topology as well as soot and NO formation processes in the rich primary zone of the RQL combustor, and to establish a large database for future validation of numerical simulations. The experiments were performed under relevant operating conditions up to 4.5 bar. The aerodynamic flow field was measured by Particle Image Velocimetry, the flame structure, fuel and NO distributions by Planar Laser-induced Fluorescence and soot volume fractions by Planar Laser-induced Incandescence. Additional measurements were performed by a scanning mobility particle sizer technique to record the number of soot particles per unit volume as well as the particles size. Two equivalence ratio conditions were used to study the impact of relevant scalar parameters on NO and soot production. For each condition, instantaneous and average distributions of the measured parameters are presented and discussed. The coupling of the optical and intrusive measurement techniques has finally enabled to highlight the impact of the liquid and gas phases fuel distribution on the flame structure, but also on NO and soot formation.

Lachaux, Thierry, Mark P. B. Musculus, Satbir Singh e Rolf D. Reitz. "Optical Diagnostics of a Late Injection Low-Temperature Combustion in a Heavy Duty Diesel Engine". In ASME 2007 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/icef2007-1703.

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A late injection, high exhaust-gas recirculation (EGR)-rate, low-temperature combustion strategy was investigated in a heavy-duty diesel engine using a suite of optical diagnostics: chemiluminescence for visualization of ignition and combustion, laser Mie scattering for liquid fuel imaging, planar laser-induced fluorescence (PLIF) for both OH and vapor-fuel imaging, and laser-induced incandescence (LII) for soot imaging. Fuel is injected at top dead center when the in-cylinder gases are hot and dense. Consequently, the maximum liquid fuel penetration is 27 mm, which is short enough to avoid wall impingement. The cool flame starts 4.5 crank angle degrees (CAD) after the start of injection (ASI), midway between the injector and bowl-rim, and likely helps fuel to vaporize. Within a few CAD, the cool-flame combustion reaches the bowl-rim. A large premixed combustion occurs near 9 CAD ASI, close to the bowl rim. Soot is visible shortly afterwards along the walls, typically between two adjacent jets at the head vortex location. OH PLIF indicates that premixed combustion first occurs within the jet and then spreads along the bowl rim in a thin layer, surrounding soot pockets at the start of the mixing-controlled combustion phase near 17 CAD ASI. During the mixing-controlled phase, soot is not fully oxidized and is still present near the bowl-rim late in the cycle. At the end of combustion near 27 CAD ASI, averaged PLIF images indicate two separate zones. OH PLIF appears near the bowl rim, while broadband PLIF persists late in the cycle near the injector. The most likely source of broadband PLIF is unburned fuel, which indicates that the near-injector region is a potential source of unburned hydrocarbons.

Soworka, T., T. Behrendt, C. Hassa, J. Heinze, E. Magens, M. Schroll, F. di Mare, S. Ballantyne e J. Gregory. "Experimental Investigation of a RQL Burner With Jet in Cross Flow Fuel Injection: Characterization of the Reacting Flow Field at Realistic Operating Conditions". In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-91244.

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Abstract Future rich-burn/quick-quench/lean-burn (RQL) burners for aero engines face the challenge to further reduce the emission of soot. Alternative ways of fuel injection are therefore in the focus of modern RQL combustion systems. This contribution aims to investigate experimentally the influence of fuel injection on the reacting flow field, with the emphasis on soot production in the primary zone. For the test, a Rolls-Royce prototype burner was used in two different configurations which differ only in the axial location of jet in cross flow fuel injection and thereby provoke different ways of fuel atomization. In the upstream configuration the burner features characteristics of a pre-filming airblast atomizer. Whereas with the fuel tip in downstream position solely Jet-in-Cross-Flow fuel atomisation is expected. The burner was tested at realistic aero engine combustor conditions (p30 = 9.28 bar, T30 = 603 K, AFR = 7.6). Several optical measurement techniques were used to characterise the reacting flow field. Their difficult application in a rich burn environment is described briefly. The structure of the reacting flow field is illustrated by Particle-Image-Velocimetry (PIV). Planar Mie scattering and Planar Laser-Induced Fluorescence (PLIF) are used to characterise the placement of liquid and gaseous fuel respectively. The location and structure of heat release zones are captured in terms of OH* and CO2* chemiluminescence. Finally Laser-Induced-Incandescence (LII) is used to obtain three dimensional soot distributions in the primary zone. On this basis 20% less soot was measured for the upstream configuration at the axial location of maximal soot concentration. This remarkable difference could be attributed to the different placement of liquid fuel and the resulting better mixing.

Maffina, Aurora, Mathieu Roussillo, Philippe Scouflaire, Nasser Darabiha, Denis Veynante, Sebastien Candel e Benedetta Franzelli. "Role of the Equivalence Ratio on Soot Formation in a Perfectly Premixed Turbulent Swirled Flame: A Combined Experimental and LES Study". In ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gt2023-104174.

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Abstract The understanding of processes that govern soot production in aero-engines is fundamental for the design of new combustion systems with low environmental impact. For this, the development of numerical models that allow for soot accurate prediction for a limited computational cost is required. Many combustors, more specifically those used in aero-engines, feature rich flame regions typically exploited in the so-called Rich-Quench-Lean (RQL) technology. Thus, it is important to complete the data on soot formation in turbulent flames that exist in the literature, by considering rich turbulent flames operating in the premixed mode. To this purpose, a model scale swirled combustor, called EM2Soot, was designed at the EM2C laboratory to analyze soot production under perfectly premixed rich conditions. In this work, the effect of the equivalence ratio on soot production in this burner is experimentally characterized and numerically simulated. Measurements of Planar Laser Induced Fluorescence of Polycyclic Aromatic Hydrocarbons (PLIF-PAH) were performed to examine soot precursors presence, whereas soot volume fraction is measured with Planar Laser Induced Incandescence (LII). Large Eddy Simulations (LES) are carried out using an analytically-reduced chemistry for the gas phase simulation in combination with a three-equation model for the solid phase description. By considering a range of equivalence ratios, the soot volume fraction from the experiments was found to reach a maximum near ϕ = 1.8, whereas a lower level of soot volume fraction was measured for lower and for higher equivalence ratios. The large eddy simulations performed in parallel are found to be in qualitative agreement with experimental data in terms of PAHs location and soot presence. The soot volume fractions fv are notably overestimated with respect to the LII measurements, suggesting the need for improved modeling schemes. However, the numerical results correctly retrieve a reduction of soot production for the highest considered equivalence ratio value and can be used to explain the experimental behaviour. Results indicate that LES gives access to a qualitative understanding of the interactions between flame, turbulent flow, and precursors governing soot formation in this system.