Download or read book Development of a Diagonal Excitation observation Diagnostic Technique for Planar Laser induced Fluorescence of the Methyne Radical in Diesel Engines written by Mark P. Musculus and published by . This book was released on 1998 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Tracer based Planar Laser induced Fluorescence Diagnostics written by Brian Ho-yin Cheung and published by Stanford University. This book was released on 2011 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two advances to tracer-based planar laser-induced fluorescence (PLIF) diagnostics are presented in this work. The first improvement is the development of a 3-pentanone fluorescence quantum yield (FQY) database and model for a wide range of conditions in support of quantitative PLIF diagnostics. In addition, this work presents a sensitive, time-resolved tracer-based PLIF diagnostic, accomplished by using a continuous-wave (CW) laser with the high-FQY tracer toluene. Because of its ease of use and desirable photophysical properties, PLIF diagnostics using 3-pentanone as a tracer are common, particularly for internal combustion engine (ICE) diagnostics. Thus, there is a need for 3-pentanone FQY measurements and modeling over a wide range of temperatures, pressures, and excitation wavelengths. For insight into the collisionless process in the FQY model, measurements were made in 3-pentanone vapor at low-pressures across a range of temperatures using a flowing cell. Laser excitation with 248, 266, 277, 308 nm wavelengths were utilized, and Rayleigh scattering of the laser beam was used to calibrate the optical efficiency of the collection optics and detector. This low-pressure data allows calculation of the 3-pentanone fluorescence rate and non-radiative de-excitation rate in the fluorescence model. The vibrational relaxation cascade parameter for 3-pentanone collisions was also determined. Measurements of 3-pentanone FQY were also made over a range of temperatures and pressures relevant to diagnostic applications, and, in particular, combined high-temperature and high-pressure conditions applicable to internal combustion engines (ICE). These data were collected in a custom-built optical cell capable of simultaneous high-pressure and high-temperature conditions. The behavior of the FQY in nitrogen for temperatures up to 745 K and in air up to 570 K was examined for pressures from 1 to 25 bar. These data were used to further optimize the parameters in the FQY model representing collisional processes. The large quantity of data with 308 nm excitation allowed optimization of the nitrogen quenching rate, and data in air were used to optimize the oxygen quenching rate. These data were also used to optimize the vibrational relaxation parameters for nitrogen and oxygen. The model with the updated parameters is consistent with the data collected in the current work, as well as with fluorescence measurements made in optical ICEs up to 1100 K and 28 bar. Another area of tracer-based PLIF diagnostics development is time-resolved imaging. Because PLIF diagnostics are often performed using pulsed lasers, the time resolution of measurements is limited to the pulse rate of laser. Use of a high-powered visible laser with an off-the-shelf cavity frequency doubler is shown to produce a moderate-power CW beam in the ultraviolet wavelength regime. Application of this CW source to excite toluene, a high-FQY tracer, yields a sensitive, time-resolved tracer-based PLIF diagnostic. Fluctuation detection limits for tracer mole fraction were investigated by applying the diagnostic to an atmospheric temperature and pressure nitrogen jet seeded with 4% toluene, and detection limits of better than 1% of the maximum toluene mole fraction were achieved for detection of fluorescence signal at a point, along a line, and over a plane. The diagnostic was also demonstrated on a turbulent jet for line and planar detection and demonstrated the potential for toluene time-resolved PLIF diagnostics with CW lasers.

Download or read book Development and Application of Tracer based Planar Laser induced Fluorescence Imaging Diagnostics for HCCI Engines written by Jordan Andrew Snyder and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Homogeneous charge compression ignition (HCCI) is an emerging engine strategy that can provide both high efficiency and low emissions, particularly in terms of NOx and soot. An important challenge of HCCI is the inherent narrow load range, bounded by combustion instability and misfires at low-load, and high pressure rise- rate (PRR) at high-load. In response, researchers have devised a number of strategies to expand the limits of HCCI operation. Negative valve overlap (NVO) with pilot injection can extend the low-load gasoline HCCI operating limit by increasing sensible energy during main compression through hot residual gas retention. Chemical effects due to reformation of the pilot injection may further impact combustion. Similarly, the high-load limit can be extended by increasing naturally occurring thermal stratification (TS) of the in- cylinder charge. These non-uniformities result in sequential auto-ignition that can effectively lower the PRR and thus expand the high-load limit. While demonstrations of these strategies have been successful and multiple engine studies have been completed, further characterization of key processes such as residual gas mixing and TS development is needed. This motivates the development of quantitative imaging diagnostics to improve the understanding of these complicated processes. In this study, tracer-based planar laser-induced fluorescence (PLIF) diagnostics for temperature and composition have been refined and optimized for application in HCCI engines at both load extremes. Acetone and 3-pentanone (both ketones) have been selected as seeded PLIF tracers as they provide good overall sensitivity and performance. Single-line and two-line diagnostic variations have been investigated, with an emphasis on optimizing overall diagnostic performance through excitation wavelength selection. Based on a detailed uncertainty analysis excitation wavelengths of 277 nm and 308 nm were selected for subsequent studies. Resulting single-shot temperature precisions were typically on the order 4 K and 12 K for the single-line and two-line techniques respectively. The corresponding mole fraction precision for the two-line technique was typically 4-5%. These results are consistent with the uncertainty analysis and demonstrate the utility of the optimization. HCCI studies were performed in two optically accessible engines, each configured for a specific load extreme. Residual mixing for low-load HCCI operation with NVO was first studied using the two-line technique to provide the simultaneous temperature and composition distribution. These measurements indicated rapid mixing of retained residuals during gas exchange and early compression, reaching a steady-state value midway through compression. Temperature stratification gradually increased throughout the remainder of compression while compositional stratification effectively remained constant. Variation of operating parameters such as main and NVO injection timing exhibited minimal differences in thermal or compositional stratification during main compression. Measurement during NVO recompression and re-expansion were also acquired to assess the in-cylinder temperatures stratification prior to chemical reaction and gas exchange. Next the development of thermal stratification for high-load HCCI with conventional valve timing was investigated using the single-line technique. These studies indicated a progressive increase in TS during compression, reaching a maximum standard deviation of 10 K at top dead center. Comparison of results for motored and fired operation exhibited similar trends. This finding indicates that the mechanism producing the TS is the same for both cases, although some differences in magnitude can occur. A subsequent parametric study proved that these differences can be attributed to the impact of both incomplete fuel mixing and cylinder-wall temperature variation, depending on the type of engine operation (DI skipfiring or premixed continuous firing). All measurements demonstrate the feasibility of quantitative tracer-based PLIF diagnostics in harsh engine environments and provide useful information for future HCCI engine development.

Download or read book Development and Optimisation of Two line Planar Laser Induced Fluorescence Technique for Combustion Measurements written by Mohammadreza Anbari Attar and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study has focused on development, optimisation and implementation of the 2-line Planar Laser Induced Fluorescence (2-line PLIF) technique for combustion measurements on a single cylinder optical Gasoline Direct Injection (GDI) engine with both Spark Ignition (SI) and Controlled Auto Ignition (CAI) combustion operations. The CAI combustion was achieved by employing Negative Valve Overlap (NVO). Two excitation wavelengths at 308 nm (directly from a XeCl laser) and 277 nm (via Raman shifting a KrF laser output at 248 nm) were exploited for the measurements. A calibration curve of fluorescence signal intensity ratio of the two laser beams as a function of temperature was obtained by conducting a series of static tests on a specially designed Constant Volume Chamber (CVC). The developed technique was validated by measurements of in-cylinder charge temperature during the compression stroke for both motoring and firing cycles and comparing the PLIF values with the temperature values calculated from in-cylinder pressure data assuming a polytropic compression. Following the validation measurements, the technique was applied to study of fuel spray characteristics and simultaneous measurements of in-cylinder charge temperature and mole fraction of Exhaust Gas Residuals (EGR). Further optimisation of the thermometry technique by enhancing the fluorescence Signal to Noise Ratio (SNR) and improving both the temporal and spatial resolutions as well as measurements precision provided the opportunity to apply the technique to other combustion measurements. The thesis presents the first application of the 2-line PLIF diagnostic in study of direct injection charge cooling effects and study of flame thermal stratification in IC engines.

Download or read book Tracer based Planar Laser induced Fluorescence Diagnostics written by Brian Ho-yin Cheung and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Two advances to tracer-based planar laser-induced fluorescence (PLIF) diagnostics are presented in this work. The first improvement is the development of a 3-pentanone fluorescence quantum yield (FQY) database and model for a wide range of conditions in support of quantitative PLIF diagnostics. In addition, this work presents a sensitive, time-resolved tracer-based PLIF diagnostic, accomplished by using a continuous-wave (CW) laser with the high-FQY tracer toluene. Because of its ease of use and desirable photophysical properties, PLIF diagnostics using 3-pentanone as a tracer are common, particularly for internal combustion engine (ICE) diagnostics. Thus, there is a need for 3-pentanone FQY measurements and modeling over a wide range of temperatures, pressures, and excitation wavelengths. For insight into the collisionless process in the FQY model, measurements were made in 3-pentanone vapor at low-pressures across a range of temperatures using a flowing cell. Laser excitation with 248, 266, 277, 308 nm wavelengths were utilized, and Rayleigh scattering of the laser beam was used to calibrate the optical efficiency of the collection optics and detector. This low-pressure data allows calculation of the 3-pentanone fluorescence rate and non-radiative de-excitation rate in the fluorescence model. The vibrational relaxation cascade parameter for 3-pentanone collisions was also determined. Measurements of 3-pentanone FQY were also made over a range of temperatures and pressures relevant to diagnostic applications, and, in particular, combined high-temperature and high-pressure conditions applicable to internal combustion engines (ICE). These data were collected in a custom-built optical cell capable of simultaneous high-pressure and high-temperature conditions. The behavior of the FQY in nitrogen for temperatures up to 745 K and in air up to 570 K was examined for pressures from 1 to 25 bar. These data were used to further optimize the parameters in the FQY model representing collisional processes. The large quantity of data with 308 nm excitation allowed optimization of the nitrogen quenching rate, and data in air were used to optimize the oxygen quenching rate. These data were also used to optimize the vibrational relaxation parameters for nitrogen and oxygen. The model with the updated parameters is consistent with the data collected in the current work, as well as with fluorescence measurements made in optical ICEs up to 1100 K and 28 bar. Another area of tracer-based PLIF diagnostics development is time-resolved imaging. Because PLIF diagnostics are often performed using pulsed lasers, the time resolution of measurements is limited to the pulse rate of laser. Use of a high-powered visible laser with an off-the-shelf cavity frequency doubler is shown to produce a moderate-power CW beam in the ultraviolet wavelength regime. Application of this CW source to excite toluene, a high-FQY tracer, yields a sensitive, time-resolved tracer-based PLIF diagnostic. Fluctuation detection limits for tracer mole fraction were investigated by applying the diagnostic to an atmospheric temperature and pressure nitrogen jet seeded with 4% toluene, and detection limits of better than 1% of the maximum toluene mole fraction were achieved for detection of fluorescence signal at a point, along a line, and over a plane. The diagnostic was also demonstrated on a turbulent jet for line and planar detection and demonstrated the potential for toluene time-resolved PLIF diagnostics with CW lasers.

Download or read book Optical and Laser Diagnostics written by C Arcoumanis and published by CRC Press. This book was released on 2016-04-19 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the automotive industry to blood flow monitoring, optical techniques and laser diagnostics are becoming integral parts in engineering and medical instrumentation. Written by leading global experts from industry, academic groups, and laboratories, this volume provides an international perspective on both existing applications and leading-edge r

Download or read book Development and Application of Infrared and Tracer based Planar Laser induced Fluorescence Imaging Diagnostics written by David A. Rothamer and published by . This book was released on 2007 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: IR-PLIF measurements of temperature and pressure are a new application of the technique. Initial IR-PLIF measurements focused on species concentrations of CO and CO2. The strong dependence of IR-PLIF signals on temperature and pressure indicated that IR-PLIF measurements of those quantities are possible.

Download or read book Laser Diagnostics for Combustion Temperature and Species written by Alan C. Eckbreth and published by CRC Press. This book was released on 2022-01-27 with total page 630 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book examines the variety of potential laser diagnostic techniques and presents a considerable theoretical foundation elucidating physics relevant to the laser diagnostics. It explains the Raman-based approaches for major species and temperature measurements.

Download or read book Planar Laser induced Fluorescence Measurements of the Hydroxyl Radical Concentration in an Acoustically Excited Dump Combustor written by Christopher P. Cadou and published by . This book was released on 1991 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quantitative Planar Laser Induced Fluorescence Technology written by Zhen Yang and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Planar laser-induced fluorescence (PLIF) is a highly sensitive and space-time-resolved laser diagnostic technique. It is widely used in the diagnosis of combustion and flow fields to obtain the thermodynamic information of active components and interested molecules in flames. Nowadays, the PLIF technology is developing in two directions: high speed and quantification. In view of the high spatial and temporal resolution characteristics of PLIF technology that other laser diagnostics do not possess, this chapter will focus on the basic principle of laser-induced fluorescence and the current research status of quantitative PLIF technology. In addition, the advantages and disadvantages of various quantitative technologies of component concentration in flames based on laser-induced fluorescence technology are analyzed. At last, the latest works on the quantification of species concentration using planar laser-induced fluorescence in combustion are introduced.

Download or read book Laser Induced Fluorescence and Ionization Techniques for Combustion Diagnostics written by BE. Forch and published by . This book was released on 1990 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Light atomic species such as oxygen atoms (O) and hydrogen atoms (H) are fundamentally important in a wide variety of combustion-related phenomena such as flame ignition, propagation, extinction and in chemical flame reactions. Furthermore, they are difficult to detect by conventional laser based optical methods (laser induced fluorescence) in combustion environments because the necessary resonance excitation wavelengths fall far into the vacuum ultraviolet (vuv) and the requisite tunable laser sources are not generally available. However, recent developments in nonlinear spectroscopic techniques such as multiphoton induced emission (MPE) and multiphoton ionization (MPI) have made direct detection of these light atoms possible. We have utilized a number of laser multiphoton excitation schemes for their detection using tunable lasers in the 190 to 400 nm range. Similar diagnostic techniques were attempted for the detection of carbon (C) and nitrogen (N) atoms in flames. The effects of laser induced photochemical pertubations on species detection in flames were also investigated. These nonlinear spectroscopic techniques have been demonstrated to be very useful in combustion studies but special care needs to be taken with respect to possible perturbations that may result from the use of short-wavelength lasers.

Download or read book Excitation detection strategies for OH planar laser induced fluorescence measurements in the presence of interfering fuel signal and absorption effects written by and published by . This book was released on 2011 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quantitative Plif Imaging in High Pressure Combustion written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-10 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the final report for a research project aimed at developing planar laser-induced fluorescence (PLIF) techniques for quantitative 2-D species imaging in fuel-lean, high-pressure combustion gases, relevant to modem aircraft gas turbine combustors. The program involved both theory and experiment. The theoretical activity led to spectroscopic models that allow calculation of the laser-induced fluorescence produced in OH, NO and 02 for arbitrary excitation wavelength, pressure, temperature, gas mixture and laser linewidth. These spectroscopic models incorporate new information on line- broadening, energy transfer and electronic quench rates. Extensive calculations have been made with these models in order to identify optimum excitation strategies, particularly for detecting low levels (ppm) of NO in the presence of large 02 mole fractions (10% is typical for the fuel-lean combustion of interest). A promising new measurement concept has emerged from these calculations, namely that excitation at specific wavelengths, together with detection of fluorescence in multiple spectral bands, promises to enable simultaneous detection of both NO (at ppm levels) and 02 or possibly NO, 02 and temperature. Calculations have been made to evaluate the expected performance of such a diagnostic for a variety of conditions and choices of excitation and detection wavelengths. The experimental effort began with assembly of a new high-pressure combustor to provide controlled high-temperature and high-pressure combustion products. The non-premixed burner enables access to postflame gases at high temperatures (to 2000 K) and high pressures (to 13 atm), and a range of fuel-air equivalence ratios. The chamber also allowed use of a sampling probe, for chemiluminescent detection of NO/NO2, and thermocouples for measurement of gas temperature. Experiments were conducted to confirm the spectroscopic models for OH, NO and 02. Hanson, R. K. Glenn Research Center...

Download or read book Quantitative Planar Laser induced Fluorescence Imaging of Radical Species in High Pressure Flames written by B. E. Battles and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Laser induced Fluorescence for Combustion Engine Diagnostics written by Hans Neij and published by . This book was released on 1993 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of a Sensitive and Selective Laser Diagnostic Technique for Measuring Paramagnetic Species written by Jamie Lee Lane and published by . This book was released on 2012 with total page 838 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advisor: N. P. Cernansky and David L. Miller.

Download or read book Laser Based Multiphoton Excitation Processes in Combustion Diagnostics written by and published by . This book was released on 1990 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: Light atomic species such as oxygen atoms (O) and hydrogen atoms (H) are fundamentally important in a wide variety of combustion related phenomena such as flame ignition, propagation, extinction, and in chemical flame reactions. Furthermore, they are difficult to detect by conventional laser based optical methods (laser induced fluorescence) in combustion environments because the necessary resonance excitation wavelengths fall far into the vacuum ultraviolet (vuv) and the requisite tunable laser sources are not generally available. However, recent developments in nonlinear spectroscopic techniques such as multiphoton induced emission (MPE) and multiphoton ionization (MPI) have made direct detection of these light atoms possible. We have utilized a number of laser multiphoton excitation schemes for their detection using tunable lasers in the 190-400 nm range. Similar diagnostic techniques were attempted for the detection of carbon (C) and nitrogen (N) atoms in flames. The effects of laser induced photochemical perturbations on species detection in flames were also investigated. Keywords: Atoms, Laser induced fluorescence, Multiphoton ionization, Optogalvanic, Flames, Fuel, Oxidizer, Laser, Dye laser.