Download or read book Laser Induced Incandescence Imaging for the Investigation of Soot Formation in Laminar Flames written by Robert Gray Roy and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Detailed Studies of Soot Formation in Laminar Diffusion Flames for Application to Modeling Studies written by and published by . This book was released on 1996 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation of soot formation in laminar diffusion flames showed that soot particle surface growth under laminar diffusion flame conditions ceases because of the depletion of hydrocarbon species and not soot particle reactivity loss due to thermal aging of the particles. This result was obtained through direct species concentration measurements under well-controlled conditions, while the particle reactivity effects were calculated based on premixed flame results along with particle temperature/time information available from earlier laminar diffusion flame studies. Comparisons with a soot formation model which incorporated detailed chemistry effects showed good agreement in terms of predicted and measured species concentration and soot particle field evolution. In addition, a novel technique for measuring soot volume fraction was developed based on laser-induced incandescence and was successfully applied to similar laminar diffusion flame studies. This technique was extended to droplet and turbulent diffusion flame conditions where a two-dimensional imaging approach was employed to measure soot volume fraction. Finally, the complete data set from these studies was assembled in a form suitable for dissemination on computer diskettes throughout the research community for comparison with modeling efforts.
Download or read book Investigation of Premixed Sooting Flames by Combined Laser Induced Incandescence and Laser Induced Fluorescence written by Jaclyn Dunn and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 fluorescence 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.
Download or read book Laser Imaging of Chemistry flowfield Interactions written by Joel E. Harrington and published by . This book was released on 19?? with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Models of detailed flame chemistry and soot formation are based upon experimental results obtained in steady, laminar flames. For successful application of these descriptions to turbulent combustion, it is instructive to test predictions against measurements in time-varying flowfields. This paper reports the use of optical methods to examine soot production and oxidation processes in a co-flowing, axisymmetric CH(4)/air diffusion flame in which the fuel flow rate is acoustically forced to create a time-varying flowfield. For a particular forcing condition in which tip clipping occurs (0.75 V loudspeaker excitation), elastic scattering of vertically polarized light from the soot particles increases by nearly an order of magnitude with respect to that observed for a steady flame with the same mean fuel flow rate. The visible flame luminosity and laser-induced fluorescence attributed to polycyclic aromatic hydrocarbons (PAH) are also enhanced. Peak soot volume fractions, as measured by time-resolved laser extinction/tomography at 632.8 and 454.5 mm and calibrated laser-induced incandescence (LII), show a factor of 4-5 enhancement in this flickering flame. The LII method is found to track the soot volume fraction closely and to give better signal-to-noise than the extinction measurements in both the steady and time-varying flowfields. A Mie analysis suggests that most of the enhanced soot production results from the formation of larger particles in the time-varying flowfield.
Download or read book Effects of Repetitive Pulsing on Multi kHz Planar Laser induced Incandescence Imaging in Laminar and Turbulent Flames written by and published by . This book was released on 2015 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Planar laser-induced incandescence (LII) imaging is reported at repetition rates up to 100 kHz using a burst-mode laser system to enable studies of soot formation dynamics in highly turbulent flames. Furthermore, to quantify the accuracy and uncertainty of relative soot volume fraction measurements, the temporal evolution of the LII field in laminar and turbulent flames is examined at various laser operating conditions. Under high-speed repetitive probing, it is found that LII signals are sensitive to changes in soot physical characteristics when operating at high laser fluences within the soot vaporization regime. For these laser conditions, strong planar LII signals are observed at measurement rates up to 100 kHz but are primarily useful for qualitative tracking of soot structure dynamics. However, LII signals collected at lower fluences allow sequential planar measurements of the relative soot volume fraction with a sufficient signal-to-noise ratio at repetition rates of 10-50 kHz. Finally, guidelines for identifying and avoiding the onset of repetitive probe effects in the LII signals are discussed, along with other potential sources of measurement error and uncertainty.
Download or read book A Quantitative Investigation of Soot Formation in Laminar Diffusion Flames written by Alessandro Gomez and published by . This book was released on 1986 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterization of Soot Particles in Laminar Diffusion by Laser induced Incandescence written by Alexandre Dias Flügel and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Soot Formation in Gaseous Laminar Diffusion Flames written by Changlie Wey and published by . This book was released on 1984 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development and Validation of an Experimental Apparatus for the Characterization of Soot in a Laminar Co flow Diffusion Flame Using Laser induced Incandescence written by Babak Borshanpour and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Soot Formation in Combustion written by Henning Bockhorn and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 595 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soot Formation in Combustion represents an up-to-date overview. The contributions trace back to the 1991 Heidelberg symposium entitled "Mechanism and Models of Soot Formation" and have all been reedited by Prof. Bockhorn in close contact with the original authors. The book gives an easy introduction to the field for newcomers, and provides detailed treatments for the specialists. The following list of contents illustrates the topics under review:
Download or read book Soot Formation in Laminar Diffusion Flames written by L. Alan Jarnagin and published by . This book was released on 1958 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Soot Particle Size Measurements in Laminar Premixed Ethylene Flames with Laser induced Incandescence and Scanning Mobility Particle Sizer written by Chung-Yuan Yin and published by . This book was released on 2009 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser-induced incandescence (LII) is used to obtain soot particle size measurements in laminar premixed ethylene flames. The LII signals are calibrated by comparing with the particle diameters measured with scanning mobility particle sizer (SMPS). Issues related to the calibration of LII with SMPS are discussed, such as the effects of equivalence ratio and laser fluence. LII and SMPS have similar sensitivities to equivalence ratio in terms of total surface area and total volume, but the equivalence ratio needs to be carefully controlled as it highly affects the results. High laser fluence affects LII results by vaporizing soot particles, which reduces particle size. The effect of high laser fluence is particularly noticeable in the flame positions near the surrounding air such as at high flame heights and the outer combustion zone of nonpremixed flames where particle oxidation takes place. Overall, the comparison between LII and SMPS data yields encouraging results as they exhibit similar trends. The correspondence of LII and SMPS implies that SMPS could be applied as a valuable tool to calibrate LII signals and avoid the necessity of developing complex LII models.
Download or read book Interactions Between the Reaction Zone and Soot Field in a Laminar Boundary Layer Type Diffusion Flame written by Andrés Fuentes and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Optical Measurements of Soot Formation in Laminar Premixed Propane Flames written by Dirk A. Smits and published by . This book was released on 1993 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Soot Formation at Atmospheric and Diesel Engine Conditions Using 2D Time resolved Laser Induced Incandescence written by Lyndon DeLaurey and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Detailed Modeling of Soot Formation Oxidation in Laminar Coflow Diffusion Flames written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: PhD.
Download or read book Investigation of Laser induced Incandescence and Soot Vaporization Using Time Resolved Light Scattering in a Propane Diffusion Flame written by Gregory David Yoder and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Laser-induced incandescence is a technique that uses a pulsed laser beam to heat soot particles up to levels far above the background, causing them to emit radiation as essentially blackbodies, which can then be related to the total soot volume using suitable calibration schemes. However, the temperature reached by the laser-heated particles may cause the particles to begin to vaporize, thereby changing the parameter of interest, namely the total soot volume. The primary goal of this thesis is to investigate the particle vaporization due to LII using time-resolved laser light scattering. Based on the experimental measurements in a sooting propane diffusion flame, significant particle vaporization was found to occur on the time scale of the LII laser pulse. A model was developed to describe the particle temperature and volume as the particles are heated up and vaporized by the LII laser and as the particles subsequently cooled. This heat transfer model uses a fundamental energy balance along with the Planck distribution to model the LII signal as a function of time, and was then used to estimate the influence of particle vaporization on the time-resolved LII signal.
