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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 199 records · Page 11

Characterization of Cold Sprayed CuCrAl Coated GRCop-84 Substrates for Reusable Launch Vehicles

An advanced Cu-8(at.%)Cr-4%Nb alloy developed at NASA's Glenn Research Center, and designated as GRCop-84, is currently being considered for use as combustor liners and nozzles in NASA's future generations of reusable launch vehicles (RLVs). Despite the fact that this alloy has superior mechanical and oxidation properties compared to many commercially available copper alloys, it is felt that its high temperature and environmental resistance capabilities can be further enhanced with the development and use of suitable coatings. Several coatings and processes are currently being evaluated for their suitability and future down selection. A newly developed CuCrAl has shown excellent oxidation resistance compared to current generation Cu-Cr coating alloys. Cold spray technology for depositing the CuCrAl coating on a GRCop-84 substrate is currently being developed under NASA's Next Generation Launch Technology (NGLT) Propulsion Research and Technology (PR&T) project. The microstructures, mechanical and thermophysical properties of overlay coated GRCop-84 substrates are discussed.

Raj, S . V.↗

Thermal Considerations for Reducing the Cooldown and Warmup Duration of the James Webb Space Telescope OTIS Cryo-Vacuum Test

The James Webb Space Telescope (JWST), set to launch in 2018, is NASAs next-generation flagship telescope. The Optical Telescope Element (OTE) and Integrated Science Instrument Module (ISIM) contain all of the optical surfaces and instruments to capture and analyze the telescopes infrared targets. The integrated OTE and ISIM are denoted as OTIS, and will be tested as a single unit in a critical thermal-vacuum test in mid-2017 at NASA Johnson Space Centers Chamber A facility. The payload will be evaluated for workmanship and functionality in a 20K simulated flight environment during this thermal-vacuum test. However, the sheer thermal mass of the OTIS payload as well as the restrictive gradient, rate, and contamination-related constraints placed on test components precludes rapid cooldown or warmup to its steady-state cryo-balance condition. Hardware safety considerations precludes injection of helium gas for free molecular heat transfer. Initial thermal analysis predicted that transient radiative cooldown from ambient temperatures, while meeting all limits and constraints, would take 33.3 days; warmup similarly would take 28.4 days. This paper discusses methods used to reduce transition times from the original predictions through modulation of boundary temperatures and environmental conditions. By optimizing helium shroud transition rates and heater usage, as well as rigorously re-examining previously imposed constraints, savings of up to three days on cooldown and up to a week on warmup can be achieved. The efficiencies gained through these methods allow the JWST thermal test team to create faster cooldown and warmup profiles, thus reducing the overall test duration and cost, while keeping all of the required test operations.

Thermal↗

Thermal Considerations for Reducing the Cooldown and Warmup Duration of the James Webb Space Telescope OTIS Cryo-Vacuum Test

The James Webb Space Telescope (JWST), set to launch in 2018, is NASAs next-generation flagship telescope. The Optical Telescope Element (OTE) and Integrated Science Instrument Module (ISIM) contain all of the optical surfaces and instruments to capture and analyze the telescopes infrared targets. The integrated OTE and ISIM are denoted as OTIS, and will be tested as a single unit in a critical thermal-vacuum test in mid-2017 at NASA Johnson Space Centers Chamber A facility. The payload will be evaluated for workmanship and functionality in a 20K simulated flight environment during this thermal-vacuum test. However, the sheer thermal mass of the OTIS payload as well as the restrictive gradient, rate, and contamination-related constraints placed on test components precludes rapid cooldown or warmup to its steady-state cryo-balance condition. Hardware safety considerations precludes injection of helium gas for free molecular heat transfer. Initial thermal analysis predicted that transient radiative cooldown from ambient temperatures, while meeting all limits and constraints, would take 33.3 days; warmup similarly would take 28.4 days. This paper discusses methods used to reduce transition times from the original predictions through modulation of boundary temperatures and environmental conditions. By optimizing helium shroud transition rates and heater usage, as well as rigorously re-examining previously imposed constraints, savings of up to three days on cooldown and up to a week on warmup can be achieved. The efficiencies gained through these methods allow the JWST thermal test team to create faster cooldown and warmup profiles, thus reducing the overall test duration and cost, while keeping all of the required test operations.

JWST↗

Testing and validation of the microbial environment of the NASA rodent spaceflight habitat water delivery system.

Sterilized, deionized water within a closed, self-sufficient system has been used in NASA spaceflight rodent studies for several decades. Within the specialized spaceflight rodent habitat, water is delivered through a compression spring-loaded bag system to maintain positive pressure. Refill of the drinking water occurs every 30 days by direct transfer of potable water from aboard the International Space Station (ISS). This enables long term use without a weekly water change out, which meets spaceflight requirements, but contrasts with the general guidelines for the sanitation of water delivery systems. Even though the water is iodinated to minimize microbial growth, rodents are fed a special diet of high moisture nutrient-rich food bars based on the AIN-93 diet that may contribute to microbial growth in this water system. We designed a ground study to assess the quality of drinking water that is given to rodents throughout a mission. We conducted the ground test using 20 female C57BL/6J mice housed in this specialized habitat to mimic the timeline of a 90-day mission as well as the environmental conditions (temperature, humidity, and pCO2) within the ISS. We used a novel sampling method to test water at 2-week intervals for the 90-days, and also after each 30-day refill of the water delivery system. Mice in standard vivarium cages with water bottles were also included for comparison to the habitat. The results showed that overall microbial load remained close to zero for the duration, while total organic compound concentrations increased from 1370g/L to 10650g/L over the course of 90 days but remained below the level of concern. Inorganic ions and pH were also found to be at acceptable levels. Overall, we conclude that this system is effective in delivering clean, potable water to rodents for the 90-day duration of current missions to the ISS.

water↗

Guanine Oxidation in the Genome, not RNA Editing, Accounts for Single Nucleotide Variation in the Exome of Mice Flown on Board the ISS

We have conducted a further analysis of single nucleotide variation (somatic mutation) in mice flown aboard the ISS. We used data archived in GeneLab from a cohort of 18-week-old mice were flown to the ISS, housed in the Rodent Habitat and therefore subjected to microgravity for 37 days. Mice of similar age, sex and the same strain were used for ground controls housed in identical hardware and simulating, but not matching ISS environmental conditions (temperature, humidity and gas atmosphere). Primary data consists of next generation RNA sequencing for the tissues examined: eye, liver, skeletal muscle and kidney. We used novel software, developed at NASA Ames Research Center and deployed on the NASA Ames Supercomputer, to perform variant calling for single point mutations. Unexpectedly, we discovered a high degree of somatic mutation in ISS-flown mice, compared to controls. We found that the extent of somatic mutation correlated with the degree of gene expression in the four tissue types, with the highest degree of somatic mutation observed in genes with the highest degree of expression. Careful analysis that included measurement of specific nucleotide changes that occurred demonstrated that guanine substitutions were the most frequent, consistent with the hypothesis that reactive oxygen species-mediated guanine oxidation was responsible for the hypermutation events. By contrast, adenine substitutions would be expected if gene editing were responsible for the somatic mutation. These types of substitutions were much less frequent. The implication of these findings for astronaut health in a variety of mission scenarios will be discussed.

International Space Station↗

Actively Controlled Louver for Human Spacecraft Radiator Ultraviolet (UV), Dust, and Freeze Protection

The paper examines the use of actively controlled louvers for human spacecraft radiators. State of the Art (SOA) radiators were design for Low Earth Orbit (LEO) operations where Ultraviolet (UV) radiation and dust have miniscule performance impacts. However, Artemis missions to the lunar orbit or surface will expose the radiators to high dose UV radiation and dust, which can degrade the radiator coating emissivity by up to 50% and consequently reduce performance early in missions. In addition, environmental nighttime temperatures at the lunar south pole are significantly colder and linger longer than LEO, and may require up to 4 kW of heater power to prevent coolant tubes from freezing, thawing, and rupturing. Analysis showed equipping the radiators with actively controlled louvers attenuated the UV radiation and dust effects, and limited degradation to less than 10% through End of Life (EOL) of missions. Furthermore, analysis demonstrated the ability to eliminate the heater power needed for freeze protection. Louver technology is a promising solution to maintain radiator performance and integrity for Artemis missions, but heritage louvers are passively controlled and only been used on small satellites. The technology requires maturing to active control, or motor actuated, to achieve faster thermal response times. Design considerations are discussed in this paper.

Louver↗

Laser Forming of Sheet Metal for In-Space Manufacturing Applications

As the in-space economy matures, the migration of typically Earth-bound manufacturing methods, such as metal forming and joining, up to space will be required to meet the increasing demand for refueling and supply depots, habitats, laboratories, lunar surface structures, and sites for deep-space exploration shipbuilding. Only in this way can the magnitude of individual structures begin to exceed what can be launched, deployed, docked, or inflated and allow true economies of scale to be unlocked in space. However, typical terrestrial methods of forming and shaping sheet metal require massive machinery with the ability to deflect reaction forces to a large mass in a fixed reference frame (Earth). To both limit up-mass required for manufacture and to mitigate the issues of reaction forces in the relative reference frames of space, a non-contact, laser-based method of forming metal sheet is proposed. NASA Marshall Space Flight Center (MSFC), in cooperation with DARPA and the University of Florida (UF), have begun investigation of non-contact methods of laser forming sheet metal in thermal vacuum (TVAC) conditions to great success. To date, several grades of aluminum, stainless steel, and titanium coupons have been formed via laser-induced internal stresses in these metals at both ambient atmosphere and vacuum conditions. Temperatures in these tests ranged from -120 to 60 C, and though the total energy required to induce strain does vary with workpiece temperature and environmental pressure, the method remains predictable and controllable for the materials investigated. It is believed that this method will revolutionize manufacturing in-space as it not only continues to build upon the capabilities of the laser (sensing, marking, cutting, drilling, joining, and now forming) as an all-in-one tool, but also reduces the need to counteract forming forces as would be required in mechanical bending. In theory, all required stress to induce bending is generated through thermal gradient and strain within the workpiece, meaning that the need for reaction control and fuel expense on-orbit will be limited. Archimedes once stated, “Give me a lever long enough and a fulcrum on which to place it, and I shall move the world”. With a laser as our lever and our workpiece its own fulcrum, we can move the world’s manufacturing into space.

Laser↗

High-Temperature Solid Particle Erosion Behavior of an Environmental Barrier Coating

The solid particle erosion (SPE) behavior of a state-of-the-art environmental barrier coating (EBC) was assessed at 2,192 °F (1,200 °C) using alumina (Al2O3) particulate. The effect of particle velocity, particle size, and impingement angle were investigated. Results show that the erosion damage in the EBC is primarily controlled by particle kinetic energy. In addition, the effect of impingement angle demonstrates the contribution of the tangential component of velocity.

Solid Particle Erosion↗

Visible and Near-IR Reflectance Spectra for Smectite, Sulfate And Perchlorate under Dry Conditions for Interpretation of Martian Surface Mineralogy

Visible and near-IR (VNIR) spectral data for the martian surface obtained from orbit by the MRO-CRISM and OMEGA instruments are interpreted as having spectral signatures of H2O/OH-bearing phases, including smectites and other phyllosilicates, sulfates, and high-SiO2 phases [e.g., 1-4]. Interpretations of martian spectral signatures are based on and constrained by spectra that are obtained in the laboratory on samples with known mineralogical compositions and other physicochemical characteristics under, as appropriate, Mars-like environmental conditions (e.g., temperature, pressure, and humidity). With respect to environmental conditions, differences in the absolute concentration of atmospheric H2O can effect the hydration state and therefore the spectra signatures of smectite phyllosilicates (solvation H2O) and certain sulfates (hydration H2O) [e.g., 5-7]. We report VNIR spectral data acquired under humid (laboratory air) and dry (dry N2 gas) environments for two natural smectites (nontronite API-33A and saponite SapCa-1) to characterize the effect of solvation H2O on spectral properties. We also report spectral data for the thermal dehydration products of (1) melanterite (FeSO4.7H2O) in both air and dry N2 gas and (2) Mg-perchlorate (Mg(ClO4)2.6H2O) in dry N2 environments. Spectral measurements for samples dehydrated in dry N2 were made without exposing them to humid laboratory air.

Morris, R.V.↗

High-temperature durability considerations for HSCT combustor

The novel combustor designs for the High Speed Civil Transport will require high temperature materials with long term environmental stability. Higher liner temperatures than in conventional combustors and the need for reduced weight necessitates the use of advanced ceramic matrix composites. The combustor environment is defined at the current state of design, the major degradation routes are discussed for each candidate ceramic material, and where possible, the maximum use temperatures are defined for these candidate ceramics.

Jacobson, Nathan S.↗

Environmental Barrier Coatings (EBC) for Ceramic Matrix Composite (CMC) Materials

The upper use temperature of current Environmental Barrier Coatings (EBC's) based on mullite and BSAS (EPM EBC's) is limited to -255 F due to silica volatility, chemical reactions, and high thermal conductivity. Therefore, new EBC s having low CTE, good chemical compatibility, and high melting point (greater than 2700 F ) are being investigated. Sinter-resistant, low thermal conductivity EBC s are strongly desired to achieve the UEET EBC goal of 270 F EBC surface temperature and 30 F AT over long exposures (greater than 1000 hr). Key areas affecting the upper temperature limit of current EBC s as well as the ongoing efforts to develop next generation EBC s in the UEET Program will be discussed.

Lee,Kang↗

High Temperature Degradation of Advanced Thermal and Environmental Barrier Coatings (TEBCs) by CaO-MgO-Al2O3-SiO2 (CMAS)

There is increasing interest in the degradation studies of thermal and environmental barrier coatings (TEBCs) of gas turbines by molten CaO-MgO-Al2O3-SiO2 (CMAS). CMAS minerals are usually referred as silica-containing sand dust and volcano ash materials that are carried by the intake air into gas turbines, e.g. aircraft engines. The low-melting deposits react at high temperatures (1000C) with the coating materials. This causes degradation and accelerated coating failure of the static and rotating components of the turbine engines. We discuss some preliminary results of the reactions between CMAS and Rare-Earth (RE Y, Yb, Dy, Gd, Nd and Sm) oxide stabilized ZrO2 or HfO2 systems, and the stability of the resulting oxides and silicates. Plasma sprayed hollow tube samples (outer diameter 4.7 mm, wall thickness 0.76 mm and 26 mm height) were half filled with CMAS powder, wrapped and sealed with platinum foil, and heat- treated at 1310 C for 5h. Samples were characterized by differential scanning calorimetry, X-ray diffraction and cross section electron microscopy analysis.

Thermal and environmental barrier coatings↗

X-15 conditioning and pressurization system

The cooling system for the X-15 airplane incorporates insulation partial protection against high-temperature effects plus liquid and gaseous nitrogen to control specifically environmental and equipment temperatures. Electronic-equipment cooling represents the largest load; however, other items to be considered are the pressure-suit ventilation, aerodynamic-heating effects, sensor-head cooling, and windshield antifogging. A review of various types of cooling systems indicates that an expendable, stored, cooling system is the most efficient for short-duration missions. This paper presents a description including a simplified schematic diagram of the subject system. (author)

Bouman, C P↗

Environmental Studies on Titanium Aluminide Alloys

Titanium aluminides are attractive alternatives to superalloys in moderate temperature applications (600 to 850 C) by virtue of their high strength-to-density ratio (high specific strength). These alloys are also more ductile than competing intermetallic systems. However, most Ti-based alloys tend to degrade through interstitial embrittlement and rapid oxidation during exposure to elevated temperatures. Therefore, their environmental behavior must be thoroughly investigated before they can be developed further. The goals of titanium aluminide environmental studies at the NASA Lewis Research Center are twofold: characterize the degradation mechanisms for advanced structural alloys and determine what means are available to minimize degradation. The studies to date have covered the alpha 2 (Ti3Al), orthorhombic (Ti2AlNb), and gamma (TiAl) classes of alloys.

Brindley, William J.↗

Hot gas ingestion characteristics and flow visualization of a vectored thrust STOVL concept

A 9.2 percent scale short takeoff and vertical landing (STOVL) hot gas ingestion model was designed and built by McDonnell Douglas Corporation (MCAIR) and tested in the NASA Lewis Research Center 9- by 15-Foot Low Speed Wind Tunnel (LSWT). Hot gas ingestion, the entrainment of heated engine exhaust into the inlet flow field, is a key development issue for advanced short takeoff and vertical landing aircraft. The Phase 1 test program, conducted by NASA Lewis and McDonnell Douglas Corporation, evaluated the hot ingestion phenomena and control techniques and Phase 2 test program which was conducted by NASA Lewis are both reported. The Phase 2 program was conducted at exhaust nozzles temperatures up to 1460 R and utilized a sheet laser system for flow visualization of the model flow field in and out of ground effects. Hot gas ingestion levels were measured for the several forward nozzle splay configurations and with flow control/lift improvement devices which reduced the hot gas ingestion. The model support system had four degrees of freedom, heated high pressure air for nozzle flow, and a suction system exhaust for inlet flow. The headwind (freestream) velocity for Phase 1 was varied from 8 to 90 kn, with primary data taken in the 8 to 23 kn headwind velocity range. Phase 2 headwind velocity varied from 10 to 23 kn. Results of both Phase 1 and 2 are presented. A description of the model, facility, a new model support system, and a sheet laser illumination system are also provided. Results are presented over a range of main landing gear height (model height) above the ground plane at a 10 kn headwind velocity. The results contain the compressor face pressure and temperature distortions, total pressure recovery, compressor face temperature rise, and the environmental effects of the hot gas. The environmental effects include the ground plane temperature and pressure distributions, model airframe heating, and the location of the ground flow separation. Results from the sheet laser flow visualization test are also shown.

Johns, Albert L.↗

Hot gas ingestion characteristics and flow visualization of a vectored thrust STOVL concept

The study presents results obtained at the compressor face of a 9.2-percent scale vectored thrust model in ground effects from Phases I and II of a test program to evaluate the hot ingestion phenomena and control techniques, and to conduct flow visualization of the model flowfield in and out of ground effects, respectively. A description of the model, facility, a new model support system, and a sheet laser illumination system are provided. The findings contain the compressor face pressure and temperature distortions, compressor face temperature rise, and the environmental effects of the hot gas. The environmental effects include the ground plane temperature and pressure distributions, model airframe heating, and the location of the ground flow separation. Results from the sheet laser flow visualization test are also presented.

Johns, Albert L.↗

System Being Developed to Measure the Rotordynamic Characteristics of Air Foil Bearings

Because of the many possible advantages of oil-free engine operation, interest in using air lubricated foil-bearing technology in advanced oil-free engine concepts has recently increased. The Oil-Free Turbomachinery Program at the NASA Glenn Research Center at Lewis Field has partially driven this recent push for oil-free technology. The program's goal of developing an innovative, practical, oil-free gas turbine engine for aeropropulsion began with the development of NASA's high-temperature solid-lubricant coating, PS304. This coating virtually eliminates the life-limiting wear that occurs during the startup and shutdown of the bearings. With practically unlimited life, foil air bearings are now very attractive to rotating machinery designers for use in turbomachinery. Unfortunately, the current knowledge base of these types of bearings is limited. In particular, the understanding of how these types of bearings contribute to the rotordynamic stability of turbomachinery is insufficient for designers to design with confidence. Recent work in oil-free turbomachinery has concentrated on advancing the understanding of foil bearings. A high-temperature fiber-optic displacement probe system and measurement method were developed to study the effects of speed, load, temperature, and other environmental issues on the stiffness characteristics of air foil bearings. Since high temperature data are to be collected in future testing, the testing method was intentionally simplified to minimize the need for expensive test hardware. The method measures the displacement induced upon a bearing in response to an applied perturbation load. The early results of these studies, which are shown in the accompanying figure, indicate trends in steady state stiffness that suggest stiffness increases with load and decreases with speed. It can be seen, even from these data, that stiffness is not expected to change by orders of magnitude over the normal operating range of most turbomachinery; a promising sign for their eventual integration into oil-free turbomachines. Planned future testing will generate similar plots for stiffness changes with temperature and geometry, as well as damping data. The data collected by this method represent a critical step toward understanding how to successfully apply foil air bearings to future oil-free turbomachinery systems.

Howard, Samuel A.↗

The Environmental Performance at Low Intensity, Low Temperature (LILT) of High Efficiency Triple Junction Solar Cells

A number of JPL missions, either active or in the p l d g stages, require the accurate LILT flew intensity - low temperate) climate of triple-junction solar. Although triple ignition LILT performance was reported as recently as 2002, there has been an evolutionary advance in cell technology by both U.S. space cell manufacturers that, for mission design purposes, effectively obsoletes the earlier data. As a result, JPL initiated a program to develop a database for the LILT performance of the new high performance triple junction solar cells. JPL obtained Emcore Advanced triple Juntion CIC assemblies and Spectrolab Ultra Triple Junction CIC assemblies. These cells were tested at temperature-intensity ranges designed to cover applications between 1 and 5.18 AU solar distances. 1 MeV electron irradiation from 25 E14 to 1 El5 w were performed on the cells to evaluate the combined effect of particulate radiation and LILT conditions. The effect of LILT conditions was observed to incur an increase in the variation of cell performances such that at simulted 5.18 AU conditions the average performance was approximately 30% with the best cells measuring between 32 and 34% efficiency. The 30% average efficiency compares with approximately 25% average efficiency measured on earlier technology triple junction solar cells.

triple junction↗