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May 22, 2011
05/11
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Miles, Richard B.; Lempert, Walter R
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The overall goals of this research were to develop new diagnostic tools capable of capturing unsteady and/or time-evolving, high-speed flow phenomena. The program centers around the development of Filtered Rayleigh Scattering (FRS) for velocity, temperature, and density measurement, and the construction of narrow linewidth laser sources which will be capable of producing an order MHz repetition rate 'burst' of high power pulses.
Topics: BRAIDED COMPOSITES, FLAMMABILITY, OXIDATION, TENSILE STRENGTH, THERMODYNAMIC PROPERTIES, MATERIALS...
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Jun 9, 2011
06/11
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Diskin, Glenn S.; Lempert, Walter R.; Miles, Richard B
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The vibrational relaxation of ground-state molecular oxygen (O2, X(sup 3)Sigma(sup -)(sub g)) has been observed, following stimulated Raman excitation to the first excited vibrational level (v=1). Time delayed laser-induced fluorescence probing of the ro-vibrational population distribution was used to examine the temporal relaxation behavior. In the presence of water vapor, the relaxation process is rapid, and is dominated by near-resonant vibrational energy exchange between the v=1 level of O2...
Topics: TURBINES, CLEARANCES, TURBOFAN ENGINES, ACTIVE CONTROL, DESIGN ANALYSIS, PIEZOELECTRICITY, STACKS,...
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May 23, 2011
05/11
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Forkey, Joseph N.; Lempert, Walter R.; Miles, Richard B
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Filtered Rayleigh Scattering (FRS) is a diagnostic technique which measures velocity, temperature, and pressure by determining Doppler shift, total intensity, and spectral line shape of laser induced Rayleigh-Brillouin scattering. In the work reported here, this is accomplished by using a narrow line width, injection seeded Nd-YAG laser sheet to induce Rayleigh-Brillouin scattering from a gas flow. This light is passed through an optical notch filter, and transmitted light is imaged onto an...
Topics: DYNAMICAL SYSTEMS, EIGENVECTORS, FORMALISM, SCALARS, MULTIVARIATE STATISTICAL ANALYSIS, SCIENTIFIC...
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Jun 9, 2011
06/11
by
Diskin, Glenn S.; Lempert, Walter R.; Miles, Richard B
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A three level model has been developed for the analysis of Schumann-Runge band (B(sup 3)Sigma(sup -)(sub u ) (- X(sup 3)Sigma(sup -)(sub g)) laser-induced fluorescence of molecular oxygen, O2. Such a model is required due to the severe lower state depletion which can occur when transitions having relatively large absorption cross-sections are excited. Such transitions are often utilized via ArF or KrF excimer or dye-laser excitation in high temperature environments. The rapid predissociation of...
Topics: TROPOSPHERE, CORRELATION COEFFICIENTS, SOUTHEAST ASIA, ANNUAL VARIATIONS, BIOMASS BURNING,...
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Sep 20, 2010
09/10
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Lempert, Walter R.; Trucco, Richard E.; Bittner, Robert D
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In this paper, we report results of hydroxyl radical and static temperature measurements performed in the General Applied Science Laboratories-NASA HYPULSE expansion tube facility using the microwave resonance lamp absorption technique. Data were obtained as part of a series of hydrogen/air and hydrogen/oxygen combustion tests at stagnation enthalpies corresponding to Mach 17 flight speeds. Data from a representative injector configuration is compared to a full Navier-Stokes CFD solution.
Topics: CULTURE TECHNIQUES, CHEMICAL ANALYSIS, LABORATORIES, MICROORGANISMS, PROCESS CONTROL (INDUSTRY),...
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May 22, 2011
05/11
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Forkey, Joseph N.; Finkelstein, N. D.; Lempert, Walter R.; Miles, Richard B
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Filtered Rayleigh Scattering is a technique which allows for measurement of velocity, temperature, and pressure in unseeded flows, spatially resolved in 2-dimensions. We present an overview of the major components of a Filtered Rayleigh Scattering system. In particular, we develop and discuss a detailed theoretical model along with associated model parameters and related uncertainties. Based on this model, we then present experimental results for ambient room air and for a Mach 2 free jet,...
Topics: ARTIFICIAL INTELLIGENCE, KNOWLEDGE BASED SYSTEMS, QUALITY CONTROL, RULES, AGRICULTURE, COMPUTER...
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May 22, 2011
05/11
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Forkey, Joseph N.; Lempert, Walter R.; Bogdonoff, Seymour M.; Miles, Richard B.; Russell, G
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We demonstrate the use of Filtererd Rayleigh Scattering and a 3D reconstruction technique to interrogate the highly three dimensional flow field inside of a supersonic inlet model. A 3 inch by 3 inch by 2.5 inch volume is reconstructed yielding 3D visualizations of the crossing shock waves and of the boundary layer. In this paper we discuss the details of the techniques used, and present the reconstructured 3D images.
Topics: APPLICATIONS PROGRAMS (COMPUTERS), PHASE TRANSFORMATIONS, THERMAL ANALYSIS, CAPILLARY FLOW,...
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May 22, 2011
05/11
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Finkelstein, N.; Gambogi, J.; Lempert, Walter R.; Miles, Richard B.; Rines, G. A.; Finch, A.; Schwarz, R. A
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We present the development of a flexible, high power, narrow line width, tunable ultraviolet source for diagnostic application. By frequency tripling the output of a pulsed titanium-sapphire laser, we achieve broadly tunable (227-360 nm) ultraviolet light with high quality spatial and spectral resolution. We also present the characterization of a mercury vapor cell which provides a narrow band, sharp edge absorption filter at 253.7 nm. These two components form the basis for the extension of...
Topics: APPLICATIONS PROGRAMS (COMPUTERS), CONDITIONS, INPUT/OUTPUT ROUTINES, WALLS, WICKS, WORKING FLUIDS,...
