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  • 1
    Electronic Resource
    Electronic Resource
    Spectroscopic Nondestructive Evaluation of Environmental Barrier Coating Failure on Silicon-Based Ceramics (2004)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 87 (2004), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Environmental barrier coatings (EBCs) are external ceramic coatings on silicon-based ceramic components to protect them from water vapor attack in combustion environments. A spectroscopic nondestructive technique to monitor the degradation of environmental barrier coatings was investigated. Lithium oxide was selected as a spectroscopic marker material after an extensive screening of various materials for their emissivity in simulated combustion environments. Spectral response of excited lithium atoms from mullite doped with 0.025–1 wt% lithium oxide was examined under an oxy-acetylene flame. A three-layer EBC (Si/Li2O-doped mullite/BSAS) on a silicon carbide substrate, which had fine simulated cracks, showed significant lithium emission on exposure to the oxy-acetylene flame, which demonstrated the potential of emission spectroscopy as a nondestructive evaluation tool to monitor EBC degradation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1551-2916.2004.01117.x
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    Paper (German National Licenses)
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  • 2
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    Spectroscopic Nondestructive Evaluation of Environmental Barrier Coating Failure on Silicon-Based Ceramics (2004)
    Wiley
    Details
    Publication Date: 2004-06-01
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Wiley on behalf of American Ceramic Society.
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    PAPER CURRENT
  • 3
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    Electrolysis Propulsion Provides High-Performance, Inexpensive, Clean Spacecraft Propulsion (1999)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: An electrolysis propulsion system consumes electrical energy to decompose water into hydrogen and oxygen. These gases are stored in separate tanks and used when needed in gaseous bipropellant thrusters for spacecraft propulsion. The propellant and combustion products are clean and nontoxic. As a result, costs associated with testing, handling, and launching can be an order of magnitude lower than for conventional propulsion systems, making electrolysis a cost-effective alternative to state-of-the-art systems. The electrical conversion efficiency is high (〉85 percent), and maximum thrust-to-power ratios of 0.2 newtons per kilowatt (N/kW), a 370-sec specific impulse, can be obtained. A further advantage of the water rocket is its dual-mode potential. For relatively high thrust applications, the system can be used as a bipropellant engine. For low thrust levels and/or small impulse bit requirements, cold gas oxygen can be used alone. An added innovation is that the same hardware, with modest modifications, can be converted into an energy-storage and power-generation fuel cell, reducing the spacecraft power and propulsion system weight by an order of magnitude.
    Keywords: Spacecraft Propulsion and Power
    Type: Research and Technology 1997; NASA/TM-1998-206312
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    The Use of Spontaneous Raman Scattering for Hydrogen Leak Detection (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A fiber optic probe has been built and demonstrated that utilizes back scattered spontaneous Raman spectroscopy to detect and identify gaseous species. The small probe, coupled to the laser and data acquisition equipment with optical fibers, has applications in gaseous leak detection and process monitoring. The probe design and data acquisition system are described. Raman scattering theory has been reviewed and the results of intensity calculations of hydrogen and nitrogen Raman scattering are given. Because the device is in its developmental stage, only preliminary experimental results are presented here. Intensity scans across the rotational-vibrational Raman lines of nitrogen and hydrogen are presented. Nitrogen at a partial pressure of 0.077 MPa was detected. Hydrogen at a partial pressure of 2 kPa approached the lower limit of detectability with the present apparatus. Potential instrument improvements that would allow more sensitive and rapid hydrogen detection are identified.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-195373 , E-9057 , NAS 1.26:195373 , AIAA PAPER 94-2983 , Joint Propulsion Conference; Jun 27, 1994 - Jun 29, 1994; Indianapolis, IN; United States
    Format: application/pdf
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  • 5
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    Qualitative Flow Visualization of a 110-N Hydrogen/Oxygen Laboratory Model Thruster (1997)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The flow field inside a 110 N gaseous hydrogen/oxygen thruster was investigated using an optically accessible, two-dimensional laboratory test model installed in a high altitude chamber. The injector for this study produced an oxidizer-rich core flow, which was designed to fully mix and react inside a fuel-film sleeve insert before emerging into the main chamber section, where a substantial fuel film cooling layer was added to protect the chamber wall. Techniques used to investigate the flow consisted of spontaneous Raman spectra measurements, visible emission imaging, ultraviolet hydroxyl spectroscopy, and high speed schlieren imaging. Experimental results indicate that the oxygen rich core flow continued to react while emerging from the fuel-film sleeve, suggesting incomplete mixing of the hydrogen in the oxygen rich core flow. Experiments also showed that the fuel film cooling protective layer retained its integrity throughout the straight section of the combustion chamber. In the converging portion of the chamber, however, a turbulent reaction zone near the wall destroyed the integrity of the film layer, a result which implies that a lower contraction angle may improve the fuel film cooling in the converging section and extend the hardware lifetime.
    Keywords: Atomic and Molecular Physics
    Type: NASA-TM-113156 , NAS 1.15:113156 , AIAA Paper 97-2847 , E-10906 , Joint Propulsion Conference and Exhibit; Jul 06, 1997 - Jul 09, 1997; Seattle, WA; United States
    Format: application/pdf
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  • 6
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    Fiber-Optic Based Compact Gas Leak Detection System (1995)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A propellant leak detection system based on Raman scattering principles is introduced. The proposed system is flexible and versatile as the result of the use of optical fibers. It is shown that multiple species can be monitored simultaneously. In this paper oxygen, nitrogen, carbon monoxide, and hydrogen are detected and monitored. The current detection sensitivity for both hydrogen and carbon monoxide is 1% partial pressure at ambient conditions. The sensitivity for oxygen and nitrogen is 0.5% partial pressure. The response time to changes in species concentration is three minutes. This system can be used to monitor multiple species at several locations.
    Keywords: Optics
    Type: NASA-CR-198439 , E-10053 , NAS 1.26:198439 , AIAA Paper 95-2646 , 31st Joint Propulsion Conference and Exhibit; Jul 10, 1995 - Jul 12, 1995; San Diego, CA; United States
    Format: application/pdf
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  • 7
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    Electrolysis Propulsion for Spacecraft Applications (1997)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Electrolysis propulsion has been recognized over the last several decades as a viable option to meet many satellite and spacecraft propulsion requirements. This technology, however, was never used for in-space missions. In the same time frame, water based fuel cells have flown in a number of missions. These systems have many components similar to electrolysis propulsion systems. Recent advances in component technology include: lightweight tankage, water vapor feed electrolysis, fuel cell technology, and thrust chamber materials for propulsion. Taken together, these developments make propulsion and/or power using electrolysis/fuel cell technology very attractive as separate or integrated systems. A water electrolysis propulsion testbed was constructed and tested in a joint NASA/Hamilton Standard/Lawrence Livermore National Laboratories program to demonstrate these technology developments for propulsion. The results from these testbed experiments using a I-N thruster are presented. A concept to integrate a propulsion system and a fuel cell system into a unitized spacecraft propulsion and power system is outlined.
    Keywords: Atomic and Molecular Physics
    Type: NASA-TM-113157 , NAS 1.15:113157 , E-10907 , AIAA Paper 97-2948 , Joint Propulsion Conference and Exhibit; Jul 06, 1997 - Jul 09, 1997; Seattle, WA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    The Development of a Fiber Optic Raman Temperature Measurement System for Rocket Flows (1992)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A fiberoptic Raman diagnostic system for H2/O2 rocket flows is currently under development. This system is designed for measurement of temperature and major species concentration in the combustion chamber and part of the nozzle of a 100 Newton thrust rocket currently undergoing testing. This paper describes a measurement system based on the spontaneous Raman scattering phenomenon. An analysis of the principles behind the technique is given. Software is developed to measure temperature and major species concentrations by comparing theoretical Raman scattering spectra with experimentally obtained spectra. Equipment selection and experimental approach are summarized. This experimental program is part of a program, which is in progress, to evaluate Navier-Stokes based analyses for this class of rocket.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-189200 , E-7167 , NAS 1.26:189200 , Joint Propulsion Conference and Exhibi; Jun 24, 1991 - Jun 27, 1991
    Format: application/pdf
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  • 9
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    Species and temperature measurement in H2/O2 rocket flow fields by means of Raman scattering diagnostics (1992)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Validation of Computational Fluid Dynamics (CFD) codes developed for prediction and evaluation of rocket performance is hampered by a lack of experimental data. Non-intrusive laser based diagnostics are needed to provide spatially and temporally resolved gas dynamic and fluid dynamic measurements. This paper reports the first non-intrusive temperature and species measurements in the plume of a 110 N gaseous hydrogen/oxygen thruster at and below ambient pressures, obtained with spontaneous Raman spectroscopy. Measurements at 10 mm downstream of the exit plane are compared with predictions from a numerical solution of the axisymmetric Navier-Stokes and species transport equations with chemical kinetics, which fully model the combustor-nozzle-plume flowfield. The experimentally determined oxygen number density at the centerline at 10 mm downstream of the exit plane is four times that predicted by the model. The experimental number density data fall between those numerically predicted for the exit and 10 mm downstream planes in both magnitude and radial gradient. The predicted temperature levels are within 10 to 15 percent of measured values. Some of the discrepancies between experimental data and predictions result from not modeling the three dimensional core flow injection mixing process, facility back pressure effects, and possible diffuser-thruster interactions.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-189217 , E-7246 , NAS 1.26:189217 , AIAA PAPER 92-3353 , Joint Propulsion Conference and Exhibit; Jul 06, 1992 - Jul 08, 1992; Nashville, TN; United States
    Format: application/pdf
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