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Application Of Spontaneous Raman Scattering For Measurements Of Thermal Non Equilibrium In High Speed Mixing And Combustion
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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 Application of Spontaneous Raman Scattering to the Flowfield in a Scramjet Combustor by :
Download or read book Application of Spontaneous Raman Scattering to the Flowfield in a Scramjet Combustor written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: For the investigation of the ignition and reaction of fuel injected into the combustor of a Scramjet at a flight Mach number of 8 high temperature test air at supersonic speed is required. One economic possibility to simulate these inlet conditions experimentally is the use of vitiators which preheat the air by the burning of hydrogen. Downstream of the precombustor the flow is accelerated in a Laval nozzle to a Mach number of 2.15 and enters the combustor. For the numerical simulation of a supersonic reacting flow precise information concerning the physical properties during ignition and reaction are required. Optical measurements are best suited for delivering this information as they do not disturb the supersonic flow like probes and as their application is not limited by thermal stress. Raman scattering offers the possibility of measuring the static temperature and the concentration of majority species.
Book Synopsis Measurement and Simulation of Spontaneous Raman Scattering Spectra in High-Pressure, Fuel-Rich H2-Air Flames by : Nasa Technical Reports Server (Ntrs)
Download or read book Measurement and Simulation of Spontaneous Raman Scattering Spectra in High-Pressure, Fuel-Rich H2-Air Flames written by Nasa Technical Reports Server (Ntrs) and published by BiblioGov. This book was released on 2013-08 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rotational vibrational spontaneous Raman spectra (SRS) of H2, N2, and H2O have been measured in H2-air flames at pressures up to 30 atm as a first stem towards establishing a comprehensive Raman spectral database for temperatures and species in high-pressure combustion. A newly developed high-pressure burner facility provides steady, reproducible flames with a high degree of flow precision. We have obtained an initial set of measurements that indicate the spectra are of sufficient quality in terms of spectral resolution, wavelength coverage, and signal-to-noise ratio for use in future reference standards. The fully resolved Stokes and anti-Stokes shifted SRS spectra were collected in the visible wavelength range (400-700 nm) using pulse-stretched 532 nm excitation and a non-intensified CCD spectrograph with a high-speed shutter. Reasonable temperatures were determined via the intensity distribution of rotational H2 lines at stoichiometry and fuel-rich conditions. Theoretical Raman spectra of H2 were computed using a semi-classical harmonic-oscillator model with recent pressure broadening data and were compared with experimental results. The data and simulation indicated that high-J rotational lines of H2 might interfere with the N2 vibrational Q-branch lines, and this could lead to errors in N2-Raman thermometry based on the line-fitting method. From a comparison of N2 Q-branch spectra in lean H2 low-pressure (1.2 atm) and high-pressure (30 atm) flames, we found no significant line-narrowing or -broadening effects at the current spectrometer resolution of 0.04 nm.
Book Synopsis International Aerospace Abstracts by :
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1032 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 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 Thermometry in High Pressure Gases Using Spontaneous Raman Scattering by : Timothy William Haller
Download or read book Thermometry in High Pressure Gases Using Spontaneous Raman Scattering written by Timothy William Haller and published by . This book was released on 2021 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spontaneous Raman scattering from nitrogen is studied in high pressure gases. Collision frequency increases with increasing gas density, causing spectral lines to broaden due to pressure broadening and mix when the lines are strongly overlapped. Because spontaneous Raman thermometry is accomplished by fitting a simulated spectrum to an experimental spectrum, spectral models that neglect these collision-induced effects will lead to erroneous temperature inference. This work investigates the influence of high density on ro-vibrational spontaneous Raman scattering, which must be understood to obtain accurate thermometry in high pressure gases. The temperature profile through a flame front was measured at 1 atm, 3 atm, and 5 atm using spontaneous Raman scattering from nitrogen. The pressure broadening was measured for the anisotropic tensor component of spontaneous Raman scattering from room temperature nitrogen over the pressure range of 10 atm to 70 atm for three gas compositions: pure nitrogen, air, and nitrogen in argon. The unmixed line model was found to give good fits to the O and S branches for all pressures, which indicates that line mixing effects are not significant in the O and S branches over this pressure range. Using indirect experimental evidence, line mixing effects in the anisotropic component of the Q branch were inferred to be below the threshold set by the experimental spectral resolution at pressures up to 70 atm at room temperature. Assuming that the anisotropic Q branch lines mix like the isotropic lines was found to result in a small systematic error in the inferred temperature at flame temperatures, with the error increasing slowly with pressure. The bias can be removed by modeling the anisotropic spectrum separately from the isotropic spectrum. Line mixing effects should be included in the modeling of the isotropic component of the Raman spectrum, but can probably be neglected in the anisotropic component of the ro-vibrational spontaneous Raman spectrum of nitrogen
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1991 with total page 1380 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis ERDA Energy Research Abstracts by : United States. Energy Research and Development Administration
Download or read book ERDA Energy Research Abstracts written by United States. Energy Research and Development Administration and published by . This book was released on 1977 with total page 1080 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Nonequilibrium Vibrational Population Measurements in an Expanding Flow Using Spontaneous Raman Spectroscopy by : Surendra P. Sharma
Download or read book Nonequilibrium Vibrational Population Measurements in an Expanding Flow Using Spontaneous Raman Spectroscopy written by Surendra P. Sharma and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :United States. Energy Research and Development Administration. Technical Information Center Publisher : ISBN 13 : Total Pages :1682 pages Book Rating :4.3/5 (129 download)
Book Synopsis ERDA Energy Research Abstracts by : United States. Energy Research and Development Administration. Technical Information Center
Download or read book ERDA Energy Research Abstracts written by United States. Energy Research and Development Administration. Technical Information Center and published by . This book was released on 1977 with total page 1682 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Raman Scattering Temperature Measurements for Water Vapor in Nonequilibrium Dispersed Two-phase Flow by :
Download or read book Raman Scattering Temperature Measurements for Water Vapor in Nonequilibrium Dispersed Two-phase Flow written by and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Quantitative Analysis of Spectral Interference of Spontaneous Raman Scattering in High-Pressure Fuel-Rich H2-Air Combustion by : Nasa Technical Reports Server (Ntrs)
Download or read book Quantitative Analysis of Spectral Interference of Spontaneous Raman Scattering in High-Pressure Fuel-Rich H2-Air Combustion written by Nasa Technical Reports Server (Ntrs) and published by BiblioGov. This book was released on 2013-08 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a theoretical study of the spectral interferences in the spontaneous Raman scattering spectra of major combustion products in 30-atm fuel-rich hydrogen-air flames. An effective methodology is introduced to choose an appropriate line-shape model for simulating Raman spectra in high-pressure combustion environments. The Voigt profile with the additive approximation assumption was found to provide a reasonable model of the spectral line shape for the present analysis. The rotational/vibrational Raman spectra of H2, N2, and H2O were calculated using an anharmonic-oscillator model using the latest collisional broadening coefficients. The calculated spectra were validated with data obtained in a 10-atm fuel-rich H2-air flame and showed excellent agreement. Our quantitative spectral analysis for equivalence ratios ranging from 1.5 to 5.0 revealed substantial amounts of spectral cross-talk between the rotational H2 lines and the N2 O-/Q-branch; and between the vibrational H2O(0,3) line and the vibrational H2O spectrum. We also address the temperature dependence of the spectral cross-talk and extend our analysis to include a cross-talk compensation technique that removes the nterference arising from the H2 Raman spectra onto the N2, or H2O spectra.
Book Synopsis Annual Index/abstracts of SAE Technical Papers by :
Download or read book Annual Index/abstracts of SAE Technical Papers written by and published by . This book was released on 2001 with total page 912 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Surface Enhanced Raman Scattering: New Theoretical Approaches, Materials and Strategies by : Ivano Alessandri
Download or read book Surface Enhanced Raman Scattering: New Theoretical Approaches, Materials and Strategies written by Ivano Alessandri and published by Frontiers Media SA. This book was released on 2020-03-25 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Laser-induced Spontaneous and Stimulated Raman Scattering by : Chester J. Schuler
Download or read book Laser-induced Spontaneous and Stimulated Raman Scattering written by Chester J. Schuler and published by . This book was released on 1968 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:
