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 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.

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.

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.

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.

Download or read book Modern Gas Based Temperature and Pressure Measurements written by Franco Pavese and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 518 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the beginning of the preparation of this volume, we have been convinced that temperature and pressure measurements should not be separated, particularly in different applications at low temperatures. This belief has made us deeply conscious of the fact that the advanced applications and modern experimental methods of investigation in science and technology need the combination of various professional experiences and approaches. Although the book is divided into two parts (Part I by F. Pavese and Part II by G. F. Molinar), we have tried to correlate low-temperature and low-pressure measurements as much as possible. We hope that our readers will find this book, which contains a large number of experimental and reference data, useful in their effort to solve measurement problems. We are pleased to acknowledge our debt to several persons and wish to express our gratitude to them for their valuable cooperation and help: to our research group colleagues at the Istituto di Metrologia "G. Colonnetti" -IMGC (CNR), without whom the knowledge and the experience we built up during many years could not have been acquired; to G. T. McConville, M. Durieux, and K. Grohmann for revisions of and various suggestions for Part I; to V. E. Bean and C. R. Tilford of NIST and G. T. McConville for revisions of and various suggestions for Part II; and to I. Prinetti of IMGC for many valuable suggestions and careful textual revisions.

Download or read book Experimental Measurements of Pressure Temperature and Density Using High resolution N2 Coherent Anti Stokes Raman Scattering written by Mark Allen Woodmansee and published by . This book was released on 1999 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Determination of the Temperature of Gas Mixtures by Using Laser Raman Scattering written by Thom A. Coney and published by . This book was released on 1973 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: A theoretical model for the Raman rotational spectrum of air was formulated, yielding the spectral temperature dependence; and an error analysis of temperature measurement accuracies was performed. The theoretical spectra and the predicted temperature measurement error of + or - 20 K (7 percent) compared well with experimental data. These experimental data consisted of Raman spectra of air obtained for temperatures ranging from 243 to 313 K at a pressure of 1 atmosphere. The use of selected lines resulted in an experimental accuracy of + or - 13 K (-5 percent).

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ultrabroadband Coherent Anti Stokes Raman Scattering for Gas Temperature and Concentration Measurements written by Yang Ran and published by . This book was released on 2021* with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this work was to investigate and extend the capability of the ultrabroadband CARS technique for temperature and concentration measurements for multiple species and a wide range of practical applications, especially for gasification diagnostics. Practical gasification or combustion devices mainly work under high pressures. Therefore, a sufficiently short probe pulse (~2 ps) was utilized for collision-free measurements. In order to simultaneously excite multiple gas species with Raman shifts up to ~4200 cm-1, a ~7 fs pump/Stokes beam was used. Both beams are generated by a 200 kHz BBO-based OPCPA system. Based on this configuration, the experimental methods and the theoretical framework for temperature and concentration determination were developed. The accuracy and precision of this technique was at first determined in a gas oven with controlled temperatures and gas flows. In this way, temperature measurements at temperatures from 295 K up to ~1300 K were performed with excellent accuracies within ~4%. The CO detection limit in CO2 atmosphere was extended to 0.5% at room temperature and 2% at 1073 K at a pressure of 1.4 bar. Temperature and concentration measurements were further extended to 20 bar and 10 bar, respectively. The influence of the ultrabroadband spectrum on the excitation efficiencies was investigated in detail. Subsequently, ultrabroadband CARS technique was applied for the first time for coal gasification investigations. Successful CARS analytical results were obtained even for the gasification process of a single coal particle.

Download or read book Advanced High Pressure O2 H2 Technology written by S. F. Morea and published by . This book was released on 1985 with total page 762 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reportnr ISL CO 202 85 written by T. Lasser and published by . This book was released on 1985 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 1996-10-10 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt: Focusing on spectroscopically-based, spatially-precise, laser techniques for temperature and chemical composition measurements in reacting and non-reacting flows, this book makes these powerful and important new tools in combustion research

Download or read book Coherent Raman Scattering in High pressure written by and published by . This book was released on 1990 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present understanding of high-pressure/high-temperature dense-fluid behavior is derived almost exclusively from hydrodynamic and thermodynamic measurements. Such results average over the microscopic aspects of the materials and are, therefore, insufficient for a complete understanding of fluid behavior. At the present, dense-fluid models can be verified only to the extend that they agree with the macroscopic measurements. Recently, using stimulated Raman scattering, Raman induced Kerr effect scattering, and coherent anti-Stokes Raman scattering, we have been able to probe some of the microscopic phenomenology of these dense fluids. In this paper, we discuss primarily the use of CARS in conjunction with a two-stage light-gas gun to obtain vibrational spectra of shock-compressed liquid N2, O2, CO, their mixtures, CH3NO2, and N2O. These experimental spectra are compared to synthetic spectra calculated using a semiclassical model for CARS intensities and best fit vibrational frequencies, peak Raman susceptibilities, and Raman linewidths. For O2, the possibility of resonance enhancement from collision-induced absorption is addressed. Shifts in the vibrational frequencies reflect the influence of increased density and temperature on the intramolecular motion. The derived parameters suggest thermal equilibrium of the vibrational levels is established less than a few nanoseconds after shock passage. Vibrational temperatures are obtained that agree with those derived from equation-of-state calculations. Measured linewidths suggest that vibrational dephasing times have decreased to subpicosecond values at the highest shock pressures.

Download or read book Research Techniques for High Pressure and High Temperature written by G. C. Ulmer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Within the last two decades, the experimental technology for the study of high temperature solid-vapor and liquid-vapor equilibria has mushroomed so fast that· both academic and industrial research ers desirous of working in this field -- be they physical chemists, metallurgists, ceramists, petrologists, crystal chemists, or mem bers of any of the several branches of materials science -- find themselves in the situation that in order to learn the art of the latest techniques, a period of apprenticeship or residency needs be spent at an institution or laboratory currently engaged in this type of solid-vapor or liquid-vapor research. The tech niques for control of the vapor phase at total pressures of one atmosphere or greater have not been well defined in the literature. Therefore, the purpose of this volume will be to serve as a labora tory manual for the control, calibration, and measurement of high temperature-high pressure equilibria. The avowed aims of this treatment of experimental techniques are: (1) to give, in terms understandable at the graduate student level, the laboratory procedures necessary to the design and utilization of good experimental technique, (2) to list the limitations, dangers, and technical pitfalls inherent or intrinsic to the described techniques, (3) to give theory and specific data only where they are essential to the experimental design, (4) to give with each chapter references that are extensive enough to serve as a bibliography of the state-of-the-art of technique development within the last decade.

Download or read book High Temperature Gas Thermometry written by Arthur Louis Day and published by . This book was released on 1911 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Spontaneous Raman Scattering Diagnostics for High pressure Gaseous Flames written by Jun Kojima and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: