Download or read book CARS Coherent Antistokes Raman Scattering Thermometry for Low and High Pressure Combustion Systems written by Douglas A. Greenhalgh and published by . This book was released on 1986 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper discusses the theory and application of broadband CARS spectroscopy for ambient (low) and high pressure combustion thermometry. The accuracy of broadband CARS is assessed from 300-3500 Kelvin for pressures around 1 bar, and from 300-700 Kelvin for pressures from 1-20 bar. The use of CARS thermometry for both 'average' and 'instantaneous' measurements is discussed. Systematic accuracy strongly depends on the quality of the spectral model used in the CARS data analysis step, CARS spectral modelling methods are discussed. Instantaneous CARS accuracy is importantly influenced by noise arising in both the broadband dye laser and the multichannel detector. Both of these factors and their relative influences are assessed. Application of CARS thermometry is illustrated by application to both in-cylinder studies of an operating production i.c. petrol engine and to turbulent combustion in an oil-fired 30 kilowatt furnace.

Download or read book Cars coherent Anti Stokes Raman Spectroscopy Investigations in Sooting and Turbulent Flames written by Alan C.. Eckbreth and published by . This book was released on 1979 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coherent anti-Stoke Raman spectroscopy (CARS) investigations in sooting, laminar and turbulent, propane-fueled diffusion flames are reported. For a 5320 A pump wavelength, using a frequency-doubled neodymium laser, interferences can occur at very high soot densities. For N2 CARS, there are both incoherent and coherent components to the interference. The incoherent interference arises primarily from anti-Stokes fluorescence from C2 excited by Stokes laser absorption. The C2 is created by the laser vaporization of soot particulates, shown to occur even on a nanosecond time scale. The coherent interference arises most probably from electronically-resonantly enhanced wave mixing in the C2. Fortunately, neither interference is very large. By proper experimental design, interference-free CARS spectra from flame N2 can be obtained even at high soot densities. CARS signatures from N2 have been employed to map the temperature field with high spatial precision throughout a small, luminous, highly sooting, laminar propane diffusion flame. Single pulse (approx, 10 nanosecond) CARS thermometry has been demonstrated in various regions of a highly swireld, turbuelnt propane diffusion flame. Based upon these investigations, CARS continues to appear very promising for diagnostic applications to practical combustion sources. (Author).

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The application of Coherent Anti Stokes Raman Scattering to turbulent combustion thermometry written by D. A. Greenhalgh and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Technical Reports Awareness Circular TRAC written by and published by . This book was released on 1987-10 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Application of Coherent Anti Stokes Raman Scattering to Combustion Media written by Larry P. Goss and published by . This book was released on 1981 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: A laboratory-based system utilizing the Nd:YAG laser has been developed to investigate the Coherent Anti-Stokes Raman Scattering (CARS) of molecular gases in combustion. Single-shot and simultaneous experimental measurements of species concentration and temperature of combustion media are reported and compared with other optical techniques and theoretical predictions. The adverse effects of beam propagation through turbulence are investigated and discussed. A transportable hardened CARS system, constructed to operate in adverse environments, has been used to conduct a series of investigations in a practical combustion tunnel. Temperature and number-density measurements made as a function of fuel-air flow, position in the combustion tunnel, and fuel variation--including both gaseous and liquid fuels--are reported. (Author).

Download or read book Heat Release Studies by Pure Rotational Coherent Anti Stokes Raman Scattering Spectroscopy in Plasma Assisted Combustion Systems Excited by Nanosecond Discharges written by Suzanne Marie Lanier Sheehe and published by . This book was released on 2014 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: For the first topic, the applicability of pure O2 broadband Rotational Coherent Anti-Stokes Raman Scattering (RCARS) Spectroscopy at very low O2 partial pressure of ~ 8 torr or less to obtain rotational temperature has been demonstrated. Very good experimental precisions of ~ ± 1 to 2 K has been demonstrated for diffuse and volumetric plasmas excited by a repetitively pulsed nanosecond discharge. It is shown that the electron-multiplication feature of an EMCCD camera increases the signal to noise ratio significantly.

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 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 Investigation of the CARS Spectrum of Carbon Monoxide at High Pressure and Temperature written by and published by . This book was released on 1984 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spectroscopic investigations were conducted into the coherent anti- Stokes Raman spectroscopy (CARS) spectrum of CO. CARS is a remote laser diagnostic technique for temperature and species measurements in hostile combustion environments. As such it possesses considerable relevance to the Air Force in the general areas of ballistics and propulsion. This final report describes the results of investigations conducted into the effects of high pressure, specifically the phenomenon of collisional narrowing, on CARS spectra from which temperature and density information derive. Experimental studies of CARS spectra were conducted in carbon monoxide in a heated, high pressure cell over the range 300K-1500K, 1-100 atm. The spectra were used to evaluate the UTRC CARS computer code supplied to RPL for the calculation of CO CARS frequency distributions.

Download or read book Combustion Diagnostic Development and Application written by L. P. Goss and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Theory application and experimental design considerations of a coherent anti stokes raman scattering cars system for combustion diagnostics written by D. J. Clouthier and published by . This book was released on 1984 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hybrid Fs ps Rotational CARS Temperature and Oxygen Measurements in the Product Gases of Canonical Flat Flames written by and published by . This book was released on 2014 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: A hybrid fs/ps pure-rotational coherent anti-Stokes Raman scattering (CARS) scheme is systematically evaluated over a wide range of flame conditions in the product gases of two canonical flat-flame burners. Near-transform-limited, broadband femtosecond pump and Stokes pulses impulsively prepare a rotational Raman coherence, which is later probed using a high-energy, frequency-narrow picosecond beam generated by the second-harmonic bandwidth compression scheme that has recently been demonstrated for rotational CARS generation in H2/air flat flames. The measured spectra are free of collision effects and nonresonant background and can be obtained on a single-shot basis at 1 kHz. The technique is evaluated for temperature/oxygen measurements in near-adiabatic H2/air flames stabilized on the Hencken burner for equivalence ratios of [phi] = 0.20-1.20. Thermometry is demonstrated in hydrocarbon/air products for [phi] = 0.75-3.14 in premixed C2H4/air flat flames on the McKenna burner. Reliable spectral fitting is demonstrated for both shot-averaged and single-laser-shot data using a simple phenomenological model. Measurement accuracy is benchmarked by comparison to adiabatic-equilibrium calculations for the H2/air flames, and by comparison with nanosecond CARS measurements for the C2H4/air flames. Quantitative accuracy comparable to nanosecond rotational CARS measurements is observed, while the observed precision in both the temperature and oxygen data is extraordinarily high, exceeding nanosecond CARS, and on par with the best published thermometric precision by femtosecond vibrational CARS in flames, and rotational femtosecond CARS at low temperature. Threshold levels of signal-to-noise ratio to achieve 1-2% precision in temperature and O2/N2 ratio are identified. Our results show that pure-rotational fs/ps CARS is a robust and quantitative tool when applied across a wide range of flame conditions spanning lean H2/air combustion to fuel-rich sooting hydrocarbon flames.

Download or read book Accurate Measurements of Combustion Species Concentrations Using CARS Coherent Antistokes Raman Scattering written by R. L. Farrow and published by . This book was released on 1986 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present results of research at the Combustion Research Facility, Sandia National Lab., on improving the capabilities of coherent anti-Stokes Raman spectroscopy (CARS) for species concentration measurements in combustion gases. Scanning CARS experiments based on single- and multi-mode Nd:YAG lasers, and on pulse-amplified and conventional pulsed dye lasers have been used to evaluate an in situ normalization technique, to measure Raman linewidths in flames, and to determine nonresonant electronic susceptibilities. We discuss experimental and theoretical considerations affecting concentration measurement accuracy.

Download or read book Single Beam Coherent Anti Stokes Raman Scattering Spectroscopy of N2 Using a Shaped 7 Fs Laser Pulse written by and published by . This book was released on 2009 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The feasibility is explored by single-beam coherent anti-Stokes Raman scattering CARS spectroscopy of gas-phase diatomic molecules related to combusting flows, with implications for gas-phase thermometry. We demonstrate CARS of gas-phase N2 using a shaped 7 fs laser pulse, investigate the dependence of the CARS signal on the total pressure of the probed environment, both in pure N2 and in mixtures with Ar, discuss the observed signal-to-noise ratio, and suggest improvements to be considered for reliable single-shot measurements at flame temperatures.

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 Temperature and Species Concentration Measurements in Combustion Systems Using Timeresolved Dual broadband Pure Rotational Coherent Anti Stokes Raman Scattering RCARS written by Yi Gao and published by . This book was released on 2013 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book written by and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: