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  • 1
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    Experimental analysis of spallation particle trajectories in an arc-jet environment (2018)
    Elsevier
    Details
    Publication Date: 2018-05-01
    Print ISSN: 0894-1777
    Electronic ISSN: 1879-2286
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Elsevier
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    PAPER CURRENT
  • 2
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    Fabrication and Testing of Durable Redundant and Fluted-Core Joints for Composite Sandwich Structures (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The development of durable bonded joint technology for assembling composite structures is an essential component of future space technologies. While NASA is working toward providing an entirely new capability for human space exploration beyond low Earth orbit, the objective of this project is to design, fabricate, analyze, and test a NASA patented durable redundant joint (DRJ) and a NASA/Boeing co-designed fluted-core joint (FCJ). The potential applications include a wide range of sandwich structures for NASA's future launch vehicles. Three types of joints were studied -- splice joint (SJ, as baseline), DRJ, and FCJ. Tests included tension, after-impact tension, and compression. Teflon strips were used at the joint area to increase failure strength by shifting stress concentration to a less sensitive area. Test results were compared to those of pristine coupons fabricated utilizing the same methods. Tensile test results indicated that the DRJ design was stiffer, stronger, and more impact resistant than other designs. The drawbacks of the DRJ design were extra mass and complex fabrication processes. The FCJ was lighter than the DRJ but less impact resistant. With barely visible but detectable impact damages, all three joints showed no sign of tensile strength reduction. No compression test was conducted on any impact-damaged sample due to limited scope and resource. Failure modes and damage propagation were also studied to support progressive damage modeling of the SJ and the DRJ.
    Keywords: Composite Materials
    Type: NF1676L-15302 , SAMPE 2013; May 06, 2013 - May 09, 2013; Long Beach, CA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Active Oxidation of a UHTC-Based CMC (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The active oxidation of ceramic matrix composites (CMC) is a severe problem that must be avoided for multi-use hypersonic vehicles. Much work has been performed studying the active oxidation of silicon-based CMCs such as C/SiC and SiC-coated carbon/carbon (C/C). Ultra high temperature ceramics (UTHC) have been proposed as a possible material solution for high-temperature applications on hypersonic vehicles. However, little work has been performed studying the active oxidation of UHTCs. The intent of this paper is to present test data indicating an active oxidation process for a UHTC-based CMC similar to the active oxidation observed with Si-based CMCs. A UHTC-based CMC was tested in the HyMETS arc-jet facility (or plasma wind tunnel, PWT) at NASA Langley Research Center, Hampton, VA. The coupon was tested at a nominal surface temperature of 3000 F (1650 C), with a stagnation pressure of 0.026 atm. A sudden and large increase in surface temperature was noticed with negligible increase in the heat flux, indicative of the onset of active oxidation. It is shown that the surface conditions, both temperature and pressure, fall within the region for a passive to active transition (PAT) of the oxidation.
    Keywords: Composite Materials
    Type: NF1676L-12008 , 62nd International Astronautical Congress; Oct 03, 2011 - Oct 07, 2011; Cape Town; South Africa
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Remote Infrared Imaging of the Space Shuttle During Hypersonic Flight: HYTHIRM Mission Operations and Coordination (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Hypersonic Thermodynamic Infrared Measurements (HYTHIRM) project has been responsible for obtaining spatially resolved, scientifically calibrated in-flight thermal imagery of the Space Shuttle Orbiter during reentry. Starting with STS-119 in March of 2009 and continuing through to the majority of final flights of the Space Shuttle, the HYTHIRM team has to date deployed during seven Shuttle missions with a mix of airborne and ground based imaging platforms. Each deployment of the HYTHIRM team has resulted in obtaining imagery suitable for processing and comparison with computational models and wind tunnel data at Mach numbers ranging from over 18 to under Mach 5. This paper will discuss the detailed mission planning and coordination with the NASA Johnson Space Center Mission Control Center that the HYTHIRM team undergoes to prepare for and execute each mission.
    Keywords: Spacecraft Design, Testing and Performance
    Type: AIAA Paper 2011-3326 , NF1676L-12050 , 29th AIAA Applied Aerodynamics Conference; Jun 27, 2011 - Jun 30, 2011; Honolulu, HI
    Format: application/pdf
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  • 5
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    Nitric Oxide PLIF Measurements in the Hypersonic Materials Environmental Test System (HYMETS) (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Planar laser-induced fluorescence (PLIF) of naturally occurring nitric oxide (NO) has been used to obtain instantaneous flow visualization images, and to make both radial and axial velocity measurements in the HYMETS (Hypersonic Materials Environmental Test System) 400 kW arc-heated wind tunnel at NASA Langley Research Center. This represents the first application of NO PLIF flow visualization in HYMETS. Results are presented at selected facility run conditions, including some in a simulated Earth atmosphere (75% nitrogen, 20% oxygen, 5% argon) and others in a simulated Martian atmosphere (71% carbon dioxide, 24% nitrogen, 5% argon), for specific bulk enthalpies ranging from 6.5 MJ/kg to 18.4 MJ/kg. Flow visualization images reveal the presence of large scale unsteady flow structures, and indicate nitric oxide fluorescence signal over more than 70% of the core flow for specific bulk enthalpies below about 11 MJ/kg, but over less than 10% of the core flow for specific bulk enthalpies above about 16 MJ/kg. Axial velocimetry was performed using molecular tagging velocimetry (MTV). Axial velocities of about 3 km/s were measured along the centerline. Radial velocimetry was performed by scanning the wavelength of the narrowband laser and analyzing the resulting Doppler shift. Radial velocities of +/- 0.5 km/s were measured.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NF1676L-15056
    Format: application/pdf
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  • 6
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    Computational Predictions of the Hypersonic Material Environmental Test System Arc-Jet Facility (2018)
    In:  CASI
    Details
    Publication Date: 2019-11-15
    Description: The Hypersonic Materials Environmental Test System arc-jet facility located at the NASA Langley Research Center in Hampton, Virginia, is primarily used for the research, development, and evaluation of high-temperature thermal protection systems for hypersonic vehicles and reentry systems. In order to improve testing capabilities and knowledge of the test article environment, a detailed three-dimensional model of the arc-jet nozzle and free-jet portion of the flow field has been developed. The computational fluid dynamics model takes into account non-uniform inflow state profiles at the nozzle inlet as well as catalytic recombination efficiency effects at the probe surface. Results of the numerical simulations are compared to calibrated Pitot pressure and stagnation-point heat flux for three test conditions at low, medium, and high enthalpy. Comparing the results and test data indicates an effectively fully-catalytic copper surface on the heat flux probe of about 10% recombination efficiency and a 2-3 kPa pressure drop from the total pressure measured at the plenum section, prior to the nozzle. With these assumptions, the predictions are within the uncertainty of the stagnation pressure and heat flux measurements. The predicted velocity conditions at the nozzle exit were also compared and showed good agreement with radial and axial velocimetry data.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NF1676L-29443 , Journal of Thermodynamics and Heat Transfer (e-ISSN 1533-6808); 33; 1; 199-209
    Format: application/pdf
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  • 7
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    Quantitative Spectral Radiance Measurements in the HYMETS Arc Jet (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Calibrated spectral radiance measurements of gaseous emission spectra have been obtained from the HYMETS (Hypersonic Materials Environmental Test System) 400 kW arc-heated wind tunnel at NASA Langley Research Center. A fiber-optic coupled spectrometer collected natural luminosity from the flow. Spectral radiance measurements are reported between 340 and 1000 nm. Both Silicon Carbide (SiC) and Phenolic Impregnated Carbon Ablator (PICA) samples were placed in the flow. Test gases studied included a mostly-N2 atmosphere (95% nitrogen, 5% argon), a simulated Earth Air atmosphere (75% nitrogen, 20% oxygen, 5% argon) and a simulated Martian atmosphere (71% carbon dioxide, 24% nitrogen, 5% argon). The bulk enthalpy of the flow was varied as was the location of the measurement. For the intermediate flow enthalpy tested (20 MJ/kg), emission from the Mars simulant gas was about 10 times higher than the Air flow and 15 times higher than the mostly-N2 atmosphere. Shock standoff distances were estimated from the spectral radiance measurements. Within-run, run-to-run and day-to-day repeatability of the emission were studied, with significant variations (15-100%) noted.
    Keywords: Space Sciences (General)
    Type: AIAA Paper 2012-0856 , NF1676L-12847 , 50th AIAA Aerospace Sciences Meeting and Exhibit; Jan 09, 2012 - Jan 12, 2012; Nashville, TN; United States
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  • 8
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    Comparative Measurements of Earth and Martian Entry Environments in the NASA Langley HYMETS Facility (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Arc-jet facilities play a major role in the development of heat shield materials for entry vehicles because they are capable of producing representative high-enthalpy flow environments. Arc-jet test data is used to certify material performance for a particular mission and to validate or calibrate models of material response during atmospheric entry. Materials used on missions entering Earth s atmosphere are certified in an arc-jet using a simulated air entry environment. Materials used on missions entering the Martian atmosphere should be certified in an arc-jet using a simulated Martian atmosphere entry environment, which requires the use of carbon dioxide. Carbon dioxide has not been used as a test gas in a United States arc-jet facility since the early 1970 s during the certification of materials for the Viking Missions. Materials certified for the Viking missions have been used on every entry mission to Mars since that time. The use of carbon dioxide as a test gas in an arc-jet is again of interest to the thermal protection system community for certification of new heat shield materials that can increase the landed mass capability for Mars bound missions beyond that of Viking and Pathfinder. This paper describes the modification, operation, and performance of the Hypersonic Materials Environmental Test System (HYMETS) arc-jet facility with carbon dioxide as a test gas. A basic comparison of heat fluxes, various bulk properties, and performance characteristics for various Earth and Martian entry environments in HYMETS is provided. The Earth and Martian entry environments consist of a standard Earth atmosphere, an oxygen-rich Earth atmosphere, and a simulated Martian atmosphere. Finally, a preliminary comparison of the HYMETS arc-jet facility to several European plasma facilities is made to place the HYMETS facility in a more global context of arc-jet testing capability.
    Keywords: Spacecraft Design, Testing and Performance
    Type: AIAA Paper 2011-1014 , NF1676L-11103 , 49th AIAA Aerospace Sciences Meeting; Jan 04, 2011 - Jan 07, 2011; Orlando, FL; United States
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  • 9
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    Characterization and Evaluation of a Mass Efficient Heat Storage Device. (2007)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The heat sponge is a device for mass-efficient storage of heat. It was developed to be incorporated in the substructure of a reentry or hypersonic vehicle to reduce thermal protection system requirements. The heat sponge consists of a liquid-vapor mixture contained within a number of miniature pressure vessels that can be embedded within a variety of different types of structures. As temperature is increased, pressure in the miniature pressure vessels also increases so that heat absorbed through vaporization of the liquid is spread over a relatively large temperature range. Using water as a working fluid, the heat storage capacity of the liquid-vapor mixture is many times higher than that of typical structural materials and is well above that of common phase change materials over the temperature range of 660oR to 1160oR. Prototype heat sponges were fabricated and characterized. These heat sponges consisted of 1.0 inch diameter hollow stainless steel spheres with a wall thickness of 0.020 inches which had varying percentages of their interior volumes filled with water. An apparatus to measure the heat stored in these prototype heat sponges was designed, fabricated, and verified. The heat storage capacity calculated from measured temperature histories is compared to numerical predictions.
    Keywords: Mechanical Engineering
    Type: 29th International Thermal Conductivity Conference (ITCC); Jun 24, 2007 - Jun 27, 2007; Birmingham, AL; United States|17th International The Symposium (ITES); Jun 24, 2007 - Jun 27, 2007; Birmingham, AL; United States
    Format: application/pdf
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  • 10
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    Preliminary Numerical and Experimental Analysis of the Spallation Phenomenon (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The spallation phenomenon was studied through numerical analysis using a coupled Lagrangian particle tracking code and a hypersonic aerothermodynamics computational fluid dynamics solver. The results show that carbon emission from spalled particles results in a significant modification of the gas composition of the post shock layer. Preliminary results from a test-campaign at the NASA Langley HYMETS facility are presented. Using an automated image processing of high-speed images, two-dimensional velocity vectors of the spalled particles were calculated. In a 30 second test at 100 W/cm2 of cold-wall heat-flux, more than 1300 particles were detected, with an average velocity of 102 m/s, and most frequent observed velocity of 60 m/s.
    Keywords: Instrumentation and Photography
    Type: NF1676L-20135 , European Symposium on Aerothermodynamics for Space Vehicles; Mar 02, 2015 - Mar 06, 2015; Lisbon; Portugal
    Format: application/pdf
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