Download or read book Temperature and Density Measurements in a Variable Pressure Hydrogen Air Flat Flame Using Raman Spectroscopy written by Franklin M. Haas and published by . This book was released on 1989 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Temperature Density and Concentration in a Hydrogen air Flame by Excimer induced Raman Scattering written by John M. Bowling and published by . This book was released on 1988 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Species Concentration and Temperature Measurements in Low stretch Hydrogen air Counterflow Diffusion Flames Using U V Raman Scattering written by T. M. Brown and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Papers Presented at the AIAA ASME SAE ASEE 25th Joint Propulsion Conference written by and published by . This book was released on 1989 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rotational and Vibrational Raman Spectroscopy for Thermochemistry Measurements in Supersonic Flames written by Alexander C Bayeh and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High speed chemically reacting flows are important in a variety of aerospace applications, namely ramjets, scramjets, afterburners, and rocket exhausts. To study flame extinction under similar high Mach number conditions, we need access to thermochemistry measurements in supersonic environments. In the current work a two-stage miniaturized combustor has been designed that can produce open supersonic methane-air flames amenable to laser diagnostics. The first stage is a vitiation burner, and was inspired by well-known principles of jet combustors. We explored the salient parameters of operation experimentally, and verified flame holding computationally using a well-stirred reactor model. The second stage of the burner generates an external supersonic flame, operating in premixed and partially premixed modes. The very high Mach numbers present in the supersonic flames should provide a useful test bed for the examination of flame suppression and extinction using laser diagnostics. We also present the development of new line imaging diagnostics for thermochemistry measurements in high speed flows. A novel combination of vibrational and rotational Raman scattering is used to measure major species densities (O2, N2, CH4, H2O,CO2, CO, & H2) and temperature. Temperature is determined by the rotational Raman technique by comparing measured rotational spectra to simulated spectra based on the measured chemical composition. Pressure is calculated from density and temperature measurements through the ideal gas law. The independent assessment of density and temperature allows for measurements in environments where the pressure is not known a priori. In the present study we applied the diagnostics to laboratory scale supersonic air and vitiation jets, and examine the feasibility of such measurements in reacting supersonic flames. Results of full thermochemistry were obtained for the air and vitiation jets that reveal the expected structure of an under-expanded jet. Centerline traces of density, temperature, and pressure of the air jet agree well with computations, while measurements of chemical composition for the vitiation flow also agree well with predicted equilibrium values. Finally, we apply the new diagnostics to the exhaust of the developed burner, and show the first ever results for density, temperature, and pressure, as well as chemical composition in a supersonic flame. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151043
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1987 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Turbulent Reactive Flows written by R. Borghi and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 958 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent reactive flows are of common occurrance in combustion engineering, chemical reactor technology and various types of engines producing power and thrust utilizing chemical and nuclear fuels. Pollutant formation and dispersion in the atmospheric environment and in rivers, lakes and ocean also involve interactions between turbulence, chemical reactivity and heat and mass transfer processes. Considerable advances have occurred over the past twenty years in the understanding, analysis, measurement, prediction and control of turbulent reactive flows. Two main contributors to such advances are improvements in instrumentation and spectacular growth in computation: hardware, sciences and skills and data processing software, each leading to developments in others. Turbulence presents several features that are situation-specific. Both for that reason and a number of others, it is yet difficult to visualize a so-called solution of the turbulence problem or even a generalized approach to the problem. It appears that recognition of patterns and structures in turbulent flow and their study based on considerations of stability, interactions, chaos and fractal character may be opening up an avenue of research that may be leading to a generalized approach to classification and analysis and, possibly, prediction of specific processes in the flowfield. Predictions for engineering use, on the other hand, can be foreseen for sometime to come to depend upon modeling of selected features of turbulence at various levels of sophistication dictated by perceived need and available capability.
Download or read book Optics Letters written by and published by . This book was released on 1991 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Temperature and Concentration Measurements in H2 air Flames Using Rotational Raman Scattering written by B. S. Samyal and published by . This book was released on 1980 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: AIAA 13th Fluid & Plasma Dynamics Conference, Jul 14-16, 1980, Snowmass, CO.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1987 with total page 1126 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.
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 Kilo Hertz Measurements of Temperature in a Premixed Methane air Flame Using Two channel Rotational Raman Spectroscopy written by P. P. Yaney and published by . This book was released on 1987 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 International Aerospace Abstracts written by and published by . This book was released on 1997 with total page 940 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Temperature Measurement in Flames by Raman Spectroscopy written by M. A. Thomsen and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 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.
