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Laser Raman Scattering Measurements Of Differential Molecular Diffusion In Turbulent Nonpremixed Jet Flames Of Hsub 2 Cosub 2 Fuel
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Book Synopsis Laser Raman Scattering Measurements of Differential Molecular Diffusion in Turbulent Nonpremixed Jet Flames of H[sub 2]/CO[sub 2] Fuel by :
Download or read book Laser Raman Scattering Measurements of Differential Molecular Diffusion in Turbulent Nonpremixed Jet Flames of H[sub 2]/CO[sub 2] Fuel written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper explores effects of differential diffusion in nonpremixed turbulent jet flames. Pulsed Raman scattering spectroscopy is used to measure temperature and species concentrations in chemically reacting jets of H[sub 2]/CO[sub 2] into air, over a range of jet Reynolds numbers from 1,000 to 30,000 based on cold jet fluid properties. Results show significant effects of differential diffusion at all jet Reynolds numbers considered. Differential diffusion between H[sub 2] and C0[sub 2] produces differences between the hydrogen element mixture fraction ([xi][sub H]) and the carbon element mixture fraction ([xi][sub c]). The greatest effects occur on the rich side of stoichiometric, where [xi][sub H] is observed to be smaller than [xi][sub C] at all Reynolds numbers. Differential diffusion between H[sub 2] and H[sub 2]O creates a net flux of hydrogen element toward the stoichiometric contour and causes a local maximum in [xi]H that occurs near the stoichiometric condition. A differential diffusion variable [sup Z]H is defined as the difference between [xi][sub H] and [xi][sub C]. The variance Of [sup Z]H conditional on [xi][sub C] also shows that differential diffusion effects are greatest on the rich side of the flame. Conditional variances of [sup Z]H are largest at intermediate Reynolds numbers.
Book Synopsis Laser Raman Scattering Measurements of Differential Molecular Diffusion in Turbulent Nonpremixed Jet Flames of H2/CO2 Fuel by :
Download or read book Laser Raman Scattering Measurements of Differential Molecular Diffusion in Turbulent Nonpremixed Jet Flames of H2/CO2 Fuel written by and published by . This book was released on 1994 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper explores effects of differential diffusion in nonpremixed turbulent jet flames. Pulsed Raman scattering spectroscopy is used to measure temperature and species concentrations in chemically reacting jets of H2/CO2 into air, over a range of jet Reynolds numbers from 1,000 to 30,000 based on cold jet fluid properties. Results show significant effects of differential diffusion at all jet Reynolds numbers considered. Differential diffusion between H2 and C02 produces differences between the hydrogen element mixture fraction ([xi]{sub H}) and the carbon element mixture fraction ([xi]{sub c}). The greatest effects occur on the rich side of stoichiometric, where [xi]{sub H} is observed to be smaller than [xi]{sub C} at all Reynolds numbers. Differential diffusion between H2 and H2O creates a net flux of hydrogen element toward the stoichiometric contour and causes a local maximum in [xi]H that occurs near the stoichiometric condition. A differential diffusion variable {sup Z}H is defined as the difference between [xi]{sub H} and [xi]{sub C}. The variance Of {sup Z}H conditional on [xi]{sub C} also shows that differential diffusion effects are greatest on the rich side of the flame. Conditional variances of {sup Z}H are largest at intermediate Reynolds numbers.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Book Synopsis Laser Raman Scattering Measurements of Differential Diffusion in Non-reacting and Reacting Laminar and Turbulent Jet Flows by : L. L. Smith
Download or read book Laser Raman Scattering Measurements of Differential Diffusion in Non-reacting and Reacting Laminar and Turbulent Jet Flows written by L. L. Smith and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781723190957 Total Pages :196 pages Book Rating :4.1/5 (99 download)
Book Synopsis Laser Raman Diagnostics in Subsonic and Supersonic Turbulent Jet Diffusion Flames by : National Aeronautics and Space Administration (NASA)
Download or read book Laser Raman Diagnostics in Subsonic and Supersonic Turbulent Jet Diffusion Flames written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-18 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultraviolet (UV) spontaneous vibrational Raman scattering combined with laser-induced predissociative fluorescence (LIPF) is developed for temperature and multi-species concentration measurements. Simultaneous measurements of temperature, major species (H2, O2, N2, H2O), and minor species (OH) concentrations are made with a 'single' narrow band KrF excimer laser in subsonic and supersonic lifted turbulent hydrogen-air diffusion flames. The UV Raman system is calibrated with a flat-flame diffusion burner operated at several known equivalence ratios from fuel-lean to fuel-rich. Temperature measurements made by the ratio of Stokes/anti-Stokes signal and by the ideal gas law are compared. The single shot measurement precision for concentration and temperature measurement is 5 to 10 pct. Calibration constants and bandwidth factors are determined from the flat burner measurements and used in a data reduction program to arrive at temperature and species concentration measurements. These simultaneous measurements of temperature and multi-species concentrations allow a better understanding of the complex turbulence-chemistry interactions and provide information for the input and validation of CFD models. Cheng, T. S. and Wehrmeyer, J. A. and Pitz, R. W. Unspecified Center DIFFUSION FLAMES; GAS JETS; LASER INDUCED FLUORESCENCE; RAMAN SPECTRA; SUBSONIC FLOW; SUPERSONIC JET FLOW; TURBULENT JETS; CONCENTRATION (COMPOSITION); EQUATIONS OF STATE; EXCIMER LASERS; IDEAL GAS; TEMPERATURE MEASUREMENT; TURBULENT DIFFUSION; VIBRATION...
Book Synopsis Laser Raman Diagnostics in Subsonic and Supersonic Turbulent Jet Diffusion Flames by : T. S. Cheng
Download or read book Laser Raman Diagnostics in Subsonic and Supersonic Turbulent Jet Diffusion Flames written by T. S. Cheng and published by . This book was released on 1991 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Government Reports Annual Index by :
Download or read book Government Reports Annual Index written by and published by . This book was released on 1995 with total page 1142 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.
Book Synopsis Government Reports Announcements & Index by :
Download or read book Government Reports Announcements & Index written by and published by . This book was released on 1994 with total page 1028 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Conserved Scalar Fluxes Measured in a Turbulent Nonpremixed Flame by Combined Laser Doppler Velocimetry and Laser Raman Scattering by : R. W. Dibble
Download or read book Conserved Scalar Fluxes Measured in a Turbulent Nonpremixed Flame by Combined Laser Doppler Velocimetry and Laser Raman Scattering written by R. W. Dibble and published by . This book was released on 1983 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Determination of Gas Temperatures from Laser-Raman Scattering by : Jack A. Salzman
Download or read book Determination of Gas Temperatures from Laser-Raman Scattering written by Jack A. Salzman and published by . This book was released on 1971 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation was conducted on the feasibility of using Raman scattered laser light to measure local gas temperatures. Temperature error predictions were made based on the statistics of the scattering process and Raman spectral theory. Methods were developed for the calculation of temperature measurement accuracies as a function of Raman signal for different spectral line ratio schemes. The results of these theoretical calculations were compared with experimental rotational Raman data obtained from a laboratory-constructed Raman spectrophotometer. Nitrogen was used as a gas sample for a range of controlled temperatures from 253 to 313 K and pressures from 0. 5 to 5.0 atmospheres.
Book Synopsis Laser Diagnostic Development and Measurement and Modeling of Turbulent Flowfields of Jets and Wakes by : P. P. Yaney
Download or read book Laser Diagnostic Development and Measurement and Modeling of Turbulent Flowfields of Jets and Wakes written by P. P. Yaney and published by . This book was released on 1983 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt: The design and performance of a photon counting, two-channel spectroscopic system using the 6-W, 448-nm line of a cw argon ion laser is described. The two channels are formed by use of cylindrical optics and special slit mirrors set up following the exit slit of a conventional double spectrometer. The system is capable of dynamic, simultaneous measurements of either the concentrations of two gas species in cold flow or the temperature and concentration of a single gas species, such as N2, in a flame. Measurements are accomplished by recording the intensities of two spontaneous rotational Raman lines with spectral bandwidths between 0.04 and 0.08 nm. Up to 4096 samples (or reads from each of the two channels) can be recorded by a dedicated minicomputer at rates up to 10 kHz. Studies of a CH4 diffusion flame at sampling rates of 20 to 100 Hz and a room-temperature, axisymmetric C02 jet at rates up to 2.0 kHz were carried out. Analysis of the data from these studies include mean and rms profiles, probability density functions (pdf's), power spectral density functions, autocorrelation functions, cross correlation functions, and determinations of skewness and kurtosis in the pdf's and the C02 fluctuations.
Book Synopsis Laser Diagnostic Development and Measurement and Modeling of Turbulent Flowfields of Jets and Wakes. Part 3. The Development of a Two-Channel CW Time-Resolved Laser Raman Spectroscopy (TiLaRS) System for Measurements in Gas Flowfields by : P. P. Yaney
Download or read book Laser Diagnostic Development and Measurement and Modeling of Turbulent Flowfields of Jets and Wakes. Part 3. The Development of a Two-Channel CW Time-Resolved Laser Raman Spectroscopy (TiLaRS) System for Measurements in Gas Flowfields written by P. P. Yaney and published by . This book was released on 1983 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: The design and performance of a photon counting, two-channel spectroscopic system using the 6-W, 448-nm line of a cw argon ion laser is described. The two channels are formed by use of cylindrical optics and special slit mirrors set up following the exit slit of a conventional double spectrometer. The system is capable of dynamic, simultaneous measurements of either the concentrations of two gas species in cold flow or the temperature and concentration of a single gas species, such as N2, in a flame. Measurements are accomplished by recording the intensities of two spontaneous rotational Raman lines with spectral bandwidths between 0.04 and 0.08 nm. Up to 4096 samples (or reads from each of the two channels) can be recorded by a dedicated minicomputer at rates up to 10 kHz. Studies of a CH4 diffusion flame at sampling rates of 20 to 100 Hz and a room-temperature, axisymmetric C02 jet at rates up to 2.0 kHz were carried out. Analysis of the data from these studies include mean and rms profiles, probability density functions (pdf's), power spectral density functions, autocorrelation functions, cross correlation functions, and determinations of skewness and kurtosis in the pdf's and the C02 fluctuations.
Book Synopsis Laser Raman Probe for Combustion Diagnostics by : M. Lapp
Download or read book Laser Raman Probe for Combustion Diagnostics written by M. Lapp and published by . This book was released on 1982 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this work is to apply light scattering diagnostics to the study of a well-defined combustion flow. Product gas densities are measured for a turbulent jet diffusion flame through use of vibrational Raman scattering techniques. These are combined with simultaneous temperature data from Raman scattering and near-simultaneous velocity data from laser velocimetry, to give an integrated probe system for basic flame properties.
Book Synopsis Combustion Diagnostics Using Laser Spontaneous-Raman Scattering by : Perry Pappas Yaney
Download or read book Combustion Diagnostics Using Laser Spontaneous-Raman Scattering written by Perry Pappas Yaney and published by . This book was released on 1979 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: An existing computer-controlled Raman Spectroscopy system, using a pulsed nitrogen laser and a double spectrometer, was upgraded and used to measure the temperatures in the combustion plume of an afterburning J85-5 turbojet engine. The computer-fitted temperatures had standard deviations between one and three percent. The agreement with simultaneous and sequential gas-sampling probe measurements and with sequential thermocouple measurements was within five percent. Upon completion of these studies, the system was extensively modified for use with a 10-inch diameter combustion tunnel. Forty-eight sets of Raman data were taken over a wide range of operating conditions of the tunnel. The temperatures ranged from 1000 to over 2000 K using methane fuel. The turbulent diffusion flame was characterized by an unsteady appearance and was orange-yellow in color. Poisson standard deviations for 21 of the measurements averaged four percent. Measurements and spectra of the laser-induced and non-laser-induced backgrounds were also obtained and analyzed. (Author).
Book Synopsis Application of Spontaneous Raman Scattering for Measurements of Thermal Non-equilibrium in High-speed Mixing and Combustion by : Heath Heinrich Reising
Download or read book Application of Spontaneous Raman Scattering for Measurements of Thermal Non-equilibrium in High-speed Mixing and Combustion written by Heath Heinrich Reising and published by . This book was released on 2017 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mixing-induced vibrational non-equilibrium is studied in the turbulent shear layer between a high-speed jet and a surrounding hot-air coflow. The vibrational and rotational temperatures of N2 and O2 are determined by fitting measured spontaneous Raman scattering spectra to a model that allows for different equilibrium distributions of the vibrational and rotational states. The mixing of the jet fluid with the coflow gases occurs over microsecond time scales, which is sufficiently fast to induce vibrational non-equilibrium in the mixture of hot and cold gases. I measured the non-equilibrium on the hot side of the shear layer, but not on the cold side where the vibrational population in the first hot band is negligible. The effect of fluctuating temperatures on the time-averaged Raman measurement was quantified using single-shot Rayleigh thermometry. The Raman scattering results were found to be insensitive to fluctuations except where the flame is present intermittently. It was also found that the measured non-equilibrium increases in the shear layer when N2 is removed from the jet fluid, indicating that the measurements average two competing processes that occur simultaneously at a molecular scale: vibrationally hot N2 cooled by the fast jet fluid and vibrationally cold jet fluid heated by a hot coflow. An interesting inference is that the averaging effect is always present, regardless of the measurement resolution. No measurable vibrational non-equilibrium is found in the O2 molecules in the same non-reacting regions. This difference between species temperatures violates the two-temperature assumption often used in the modeling of high-temperature non-equilibrium flow. A new technique was developed to obtain spontaneous Raman scattering temperature measurements from a single laser pulse. This technique required the construction of a multiple-pass cell to obtain adequate scattered signal. Additionally, the pulse was stretched temporally with a system of partial reflectors and time-flight-delay ring cavities in order to reduce the peak power of the 1 J laser pulses. These measurements were found to be in agreement with the previous time-average results and allowed for measurement to be made near the fluctuating base of a lifted flame – a region where time-averaged measurements do not give meaningful results.
Book Synopsis Raman Imaging of Counterflow Diffusion Flames by : Serdar Yeralan
Download or read book Raman Imaging of Counterflow Diffusion Flames written by Serdar Yeralan and published by . This book was released on 1995 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogen versus air counterflow diffusion flames are studied with linewise Raman imaging system. Raman measurements are gathered over 20 second duration with high precision (2%) and high spatial resolution (160 $\mu$m). Axial strain rate values are measured by laser Doppler velocimetry. Three different fuel jet concentrations are studied: mole fractions of 21% hydrogen diluted with 79% nitrogen, 50% hydrogen diluted with 50% nitrogen and undiluted hydrogen. Axial strain rate is varied for each of the fuel dilution cases. Raman images of these flames are converted into temperature and major species mole fraction profiles. Mixture fraction and scalar dissipation rate profiles are generated from the mole fraction information. Strain rate and differential diffusion effects are clearly illustrated by the results. Numerically predicted strain rate and differential diffusion effects are experimentally matched. Peak temperatures values agree well with numerical estimates for all of the fuel dilutions except for the undiluted fuel jet cases. At least 50 K higher temperatures are observed for undiluted fuel jet flames when compared to numerically predicted temperatures of these flames. A library of mixture fraction and scalar dissipation rate is generated for hydrogen-air combustion.
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781721932153 Total Pages :202 pages Book Rating :4.9/5 (321 download)
Book Synopsis Laser-Induced Fluorescence Measurements and Modeling of Nitric Oxide in Counterflow Diffusion Flames by : National Aeronautics and Space Administration (NASA)
Download or read book Laser-Induced Fluorescence Measurements and Modeling of Nitric Oxide in Counterflow Diffusion Flames written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-27 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: The feasibility of making quantitative nonintrusive NO concentration ([NO]) measurements in nonpremixed flames has been assessed by obtaining laser-induced fluorescence (LIF) measurements of [NO] in counterflow diffusion flames at atmospheric and higher pressures. Comparisons at atmospheric pressure between laser-saturated fluorescence (LSF) and linear LIF measurements in four diluted ethane-air counterflow diffusion flames with strain rates from 5 to 48/s yielded excellent agreement from fuel-lean to moderately fuel-rich conditions, thus indicating the utility of a model-based quenching correction technique, which was then extended to higher pressures. Quantitative LIF measurements of [NO] in three diluted methane-air counterflow diffusion flames with strain rates from 5 to 35/s were compared with OPPDIF model predictions using the GRI (version 2.11) chemical kinetic mechanism. The comparisons revealed that the GRI mechanism underpredicts prompt-NO by 30-50% at atmospheric pressure. Based on these measurements, a modified reaction rate coefficient for the prompt-NO initiation reaction was proposed which causes the predictions to match experimental data. Temperature measurements using thin filament pyrometry (TFP) in conjunction with a new calibration method utilizing a near-adiabatic H2-air Hencken burner gave very good comparisons with model predictions in these counterflow diffusion flames. Quantitative LIF measurements of [NO] were also obtained in four methane-air counterflow partially-premixed flames with fuel-side equivalence ratios (phi(sub B)) of 1.45, 1.6, 1.8 and 2.0. The measurements were in excellent agreement with model predictions when accounting for radiative heat loss. Spatial separation between regions dominated by the prompt and thermal NO mechanisms was observed in the phi(sub B) = 1.45 flame. The modified rate coefficient proposed earlier for the prompt-NO initiation reaction improved agreement between code predictions and measurements in the re
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