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.

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 Development of a Laser Induced Incandescence System written by Trevor H. Kempthorne and published by . This book was released on 2010 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability to accurately measure solid particulate levels in various applications ranging from engines to laboratory flames has become very important in the past few decades. A new approach to measuring soot levels called laser-induced incandescence was investigated. An apparatus was designed and built in order to measure soot levels in an atmospheric laminar diffusion flame with the intent of conducting proof-of-concept measurements. The apparatus utilized highly focussed optics while collecting time-resolved data using fast PMTs which allowed measurement of both time and spatial domains. Although noise and other technical problems proved to be a concern, measurements with reasonable agreement with published results for temperature (2800 K) and the primary particle soot size (6.3 +/- 2.5 nm) were achieved within the flame. Noise issues with the apparatus prevented accurate soot volume fraction measurements from being obtained. Numerous suggestions have been made as to how to improve the experiment for future use, potentially in a high pressure environment.

Download or read book Advanced Non intrusive Instrumentation for Propulsion Engines written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development. Propulsion and Energetics Panel. Symposium and published by North Atlantic Treaty Organization Resear Rganization. This book was released on 1998 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The burner being characterised by a standard setup allows for comparison when using a different excitation source, a long-pulsed fibre laser. Using a long pulse fibre laser has benefits and it is shown in this work that it is possible to get a comparable result with LII centre line height above burner (HAB) profiles matching. Modelling also allows for comparisons and understanding on how the laser temporal and spatial profile can affect the LII signal.The rise of the interest in sustainable energy generation has led to the increase of using alternative fuel sources such as biofuels. Using the method developed it was possible to record soot volume fraction images within a wick diffusion flame which used a selection of biofuels and show improvement on previously published temporal profiles produced in these flames. The sooting propensity of each fuel was able to be characterised more accurately using spatially resolved profiles over temporally measured profile.

Download or read book NBS Special Publication written by and published by . This book was released on 1968 with total page 944 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization of High Temperature Vapors and Gases written by John W. Hastie and published by . This book was released on 1979 with total page 936 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 Computational and Experimental Study of Laminar Flames written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past three years, our research has centered on an investigation of the effects of complex chemistry and detailed transport on the structure and extinction of hydrocarbon flames in coflowing axisymmetric configurations. We have pursued both computational and experimental aspects of the research in parallel on both steady-state and time-dependent systems. The computational work has focused on the application of accurate and efficient numerical methods for the solution of the steady-state and time-dependent boundary value problems describing the various reacting systems. Detailed experimental measurements were performed on axisymmetric coflow flames using two-dimensional imaging techniques. Previously, spontaneous Raman scattering, chemiluminescence, and laser-induced fluorescence were used to measure the temperature, major and minor species profiles. Particle image velocimetry (PIV) has been used to investigate velocity distributions and for calibration of time-varying flames. Laser-induced incandescence (LII) with an extinction calibration was used to determine soot volume fractions, while soot surface temperatures were measured with three-color optical pyrometry using a color digital camera. A blackbody calibration of the camera allows for determination of soot volume fraction as well, which can be compared with the LII measurements. More recently, we have concentrated on a detailed characterization of soot using a variety of techniques including time-resolved LII (TiRe-LII) for soot primary particles sizes, multi-angle light scattering (MALS) for soot radius of gyration, and spectrally-resolved line of sight attenuation (spec-LOSA). Combining the information from all of these soot measurements can be used to determine the soot optical properties, which are observed to vary significantly depending on spatial location and fuel dilution. Our goal has been to obtain a more fundamental understanding of the important fluid dynamic and chemical interactions in these flames so that this information can be used effectively in combustion modeling.

Download or read book Advances in the Modeling of Time resolved Laser induced Incandescence written by Timothy Andrew Sipkens and published by . This book was released on 2018 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosolized nanoparticles represent both great potential for the development of emerging technologies and one of the biggest challenges currently facing our planet. In the former case, aerosol-based synthesis techniques represent one of the most cost-effective approaches to generating engineered nanoparticles having applications that range from medicine to energy. In the latter case, aerosolized soot is the second largest forcing factor after carbon dioxide in climate change models and contributes significantly to asthma, bronchitis, and various other respiratory illnesses. The increased predominance of engineered nanoparticles also presents significant environmental and health risks due to various toxicological effects. In any of these cases, robust characterization is critical to the function and regulation of these nanoaerosols. Time-resolved laser-induced incandescence (TiRe-LII) is well-suited to meeting this challenge. Since its inception in the 1980s, TiRe-LII has matured into a standard diagnostic for characterizing soot in combustion applications and, increasingly, engineered nanoparticles synthesized as an aerosol. The in situ nature of the technique makes it well-suited to probe in-flame soot formation and the fundamentals of nanoparticle formation. Moreover, its cost-effectiveness and real-time capabilities make TiRe-LII particularly well-suited as an avenue for online control of nanoparticle synthesis. TiRe-LII involves heating nanoparticles within a sample volume of aerosol to incandescent temperatures using a short laser-pulse. Following the laser pulse, the nanoparticles return to the ambient gas temperature via conductive and evaporative cooling. The magnitude of the peak spectral incandescence signal can be used to derive the particle volume fraction, while the temperature decay of the nanoparticles can be used to infer thermophysical properties, including the nanoparticle size, thermal accommodation coefficient (TAC), and latent heat of vaporization. Data analysis requires the use of spectroscopic models, used to convert the observed incandescence to a volume fraction or nanoparticle temperature, and heat transfer models, used to model the changes in the nanoparticle temperature over the duration of a signal. These models have evolved considerably over the past two decades, increasing the interpretive power of TiRe-LII. Nevertheless, there are several factors that impede further improvements to the reliability of TiRe-LII derived quantities. Several anomalies have been observed in measured signals collected from both engineered nanoparticle and soot, ranging from faster-than-expected temperature decays to inconsistencies in measurements between laboratories and experimental conditions. Resolving these differences is crucial to improving the robustness of TiRe-LII both as a combustion and engineered nanoparticle diagnostic. However, this first requires the development of advanced analysis tools that allow for a better understanding of nanoscale physics and the uncertainties associated with model development. This thesis presents several advances in the modeling and interpretation of TiRe-LII signals. The current state-of-the-art in TiRe-LII models is first established and the process of model inversion is discussed, with particular reference to uncertainty quantification within the Bayesian perspective. This lays the foundation for analysis of the measurement errors associated with TiRe-LII signals, providing practitioners with another source of information to characterize measurement devices and fluctuations in observed processes. Next, a novel approach to describe the relationship between the peak nanoparticle temperature and the laser fluence is derived. This allows the first comparison of fluence curves obtained using different instrumentation and under different measurement conditions. This dissertation proceeds by examining inversion of the spectroscopic model to determine both the nanoparticle temperature decay and the factor that scales emission from the nanoparticles to the observed signal. Unexpected temporal effects in the latter quantity are examined as an additional source of information that TiRe-LII practitioners can use for nanoparticle characterization and for diagnosing problems with measurement devices. Molecular dynamics simulations are employed to calculate the thermal accommodation coefficient, a parameter fundamental to the heat transfer model used in interpreting the inferred nanoparticle temperature decay, using the results are used in an analysis of TiRe-LII collected from iron, silver, and molybdenum nanoparticles. The cross-comparison of these materials highlights the utility of the developed analysis tools and provides fundamental insights into both nanoscale physics and bulk thermophysical properties. This dissertation concludes with a critical discussion of model development, emphasizing the importance of complexity and uncertainty in model selection. This is particularly important in the context of the context of the increasingly divergent set of TiRe-LII models available in the literature, indicative of model tuning. In summary, this dissertation not only presents direct improvements to the spectroscopic and heat transfer models used in traditional TiRe-LII analysis but also presents a set of new approaches by which the remaining challenges in TiRe-LII analysis can be resolved.

Download or read book Effects of Aggregate Morphology and Size on Laser induced Incandescence and Scattering from Black Carbon mature Soot written by and published by . This book was released on 2015 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: For this study, we have used a Single-Particle Soot Photometer (SP2) to measure time-resolved laser-induced incandescence (LII) and laser scatter from combustion-generated mature soot with a fractal dimension of 1.88 extracted from a burner. We have also made measurements on restructured mature-soot particles with a fractal dimension of 2.3-2.4. We reproduced the LII and laser-scatter temporal profiles with an energy- and mass-balance model, which accounted for heating of particles passed through a CW-laser beam over laser-particle interaction times of ~10 [mu]s. The results demonstrate a strong influence of aggregate size and morphology on LII and scattering signals. Conductive cooling competes with absorptive heating on these time scales; the effects are reduced with increasing aggregate size and fractal dimension. These effects can lead to a significant delay in the onset of the LII signal and may explain an apparent low bias in the SP2 measurements for small particle sizes, particularly for fresh, mature soot. In addition, the results reveal significant perturbations to the measured scattering signal from LII interference and suggest rapid expansion of the aggregates during sublimation.

Download or read book 36th Aerospace Sciences Meeting Exhibit written by and published by . This book was released on 1998 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser Induced Incandescence of Soot for High Pressure Combustion Diagnostics written by Daniel Dennis Emile Cormier and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2730 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser induced Incandescence Measurements of Soot Production in Steady and Flickering Methane Propane and Ethylene Diffusion Flames written by Christopher R. Shaddix and published by . This book was released on 1996 with total page 35 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 Using Laser Induced Incandescence to Measure Soot Smoke Concentrations written by and published by . This book was released on 1997 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: