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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 1,459 records · Page 81
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Low-speed wind tunnel investigation of a semispan STOL jet transport wing body with an upper surface blown jet flap

An investigation of the static longitudinal aerodynamic characteristics of a semispan STOL jet transport wing-body with an upper-surface blown jet flap for lift augmentation was conducted in a low-speed wind tunnel having a 12-ft octagonal test section. The semispan swept wing had an aspect ratio of 3.92 (7.84 for the full span) and had two simulated turbofan engines mounted ahead of and above the wing in a siamese pod equipped with an exhaust deflector. The purpose of the deflector was to spread the engine exhaust into a jet sheet attached to the upper surface of the wing so that it would turn downward over the flap and provide lift augmentation. The wing also had optional boundary-layer control provided by air blowing through a thin slot over a full-span plain trailing-edge flap.

Phelps, A. E., III↗
NASA NTRS2011

Mars Exploration Rover Heatshield Observation Campaign

For the first time ever, engineers were able to observe a heatshield on the surface of another planet after a successful entry through the atmosphere. A three-week heatshield observation campaign was conducted in December 2004 after the Mars Exploration Rover Opportunity rover exited "Endurance Crater." By utilizing the rover's scientific instruments, data was collected to make a qualitative assessment of the performance of the heatshield. This data was gathered to gain a better understanding of how the heatshield performed during entry through the Martian atmosphere. In addition, this unprecedented look at the heatshield offered engineers the opportunity to assess if any unexpected anomalies occurred. Once a survey of the heatshield debris was completed, multiple targets of interest were chosen for the collection of imaging data. This data was then used to assess the char depth of the thermal protection material, which compared well with computational predictions. Extensive imaging data was collected and showed the main seal in pristine conditions, and no observable indications of structure overheating. Additionally, unexpected vehicle dynamics during the atmospheric entry were explained by the observation of thermal blanket remnants attached to the heatshield.

MER↗
DOE OSTI2019

Influence of Vibration on Surface Roughness in Turning

Errors in machining and the relation between the final surface roughness and the vibration of the machining system (the lathe, the attachment, the tool, and the workpiece) are considered, for the case of turning. Software for visualization of surface roughness produced by machining is developed.

42 ENGINEERING↗
DOE OSTI2022

Self-healing Growth of LaNiO 3 on a Mixed-Terminated Perovskite Surface

Developing atomic-scale synthesis control is a prerequisite for understanding and engineering the exotic physics inherent to transition-metal oxide heterostructures. Thus, far, however, the number of materials systems explored has been extremely limited, particularly with regard to the crystalline substrate, which is routinely SrTiO 3 . Here, we investigate the growth of a rare-earth nickelate-LaNiO 3 -on (LaAlO 3 )(Sr 2 AlTaO 6 ) (LSAT) (001) by oxide molecular beam epitaxy (MBE). Whereas the LSAT substrates are smooth, they do not exhibit the single surface termination usually assumed necessary for control over the interface structure. Performing both nonresonant and resonant anomalous in situ synchrotron surface X-ray scattering during MBE growth, we show that reproducible heterostructures can be achieved regardless of both the mixed surface termination and the layer-by-layer deposition sequence. The rearrangement of the layers occurs dynamically during growth, resulting in the fabrication of high-quality LaNiO 3 /LSAT heterostructures with a sharp and consistent interfacial structure. This is due to the thermodynamics of the deposition window as well as the nature of the chemical species at interfaces-here, the flexible charge state of nickel at the oxide surface. This has important implications regarding the use of a wider variety of substrates for fundamental studies on complex oxide synthesis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2004

Droplet-Surface Impingement Dynamics for Intelligent Spray Design

Spray cooling has high potential in thermal management and life support systems by overcoming the deleterious effect of microgravity upon two-phase heat transfer. In particular spray cooling offers several advantages in heat flux removal that include the following: 1) By maintaining a wetted surface, spray droplets impinge upon a thin fluid film rather than a dry solid surface; 2. Most heat transfer surfaces will not be smooth but rough. Roughness can enhance conductive cooling, aid liquid removal by flow channeling; and 3. Spray momentum can be used to a) substitute for gravity delivering fluid to the surface, b) prevent local dryout and potential thermal runaway and c) facilitate liquid and vapor removal. Yet high momentum results in high We and Re numbers characterizing the individual spray droplets. Beyond an impingement threshold, droplets splash rather than spread. Heat flux declines and spray cooling efficiency can markedly decrease. Accordingly we are investigating droplet impingement upon a) dry solid surfaces, b) fluid films, c) rough surfaces and determining splashing thresholds and relationships for both dry surfaces and those covered by fluid films. We are presently developing engineering correlations delineating the boundary between splashing and non-splashing regions. Determining the splash/non-splash boundary is important for many practical applications. Coating and cooling processes would each benefit from near-term empirical relations and subsequent models. Such demonstrations can guide theoretical development by providing definitive testing of its predictive capabilities. Thus, empirical relations describing the boundary between splash and non-splash are given for drops impinging upon a dry solid surface and upon a thin fluid film covering a similar surface. Analytical simplification of the power laws describing the boundary between the splash and non-splash regions yields insight into the engineering parameters governing the splash and non-splash outcomes of the fluid droplets. The power law correlation is shown separating the splashing versus non-splashing regions as developed for droplets impinging upon a dry solid surface. Splashing upon a dry surface is reasonably described by Ca greater than 0.85, reflecting the competing roles of surface tension and viscosity. The power law correlation is shown separating the splashing versus non-splashing regions as developed for droplets impinging upon a thin fluid film covering the solid surface. Splashing upon a thin fluid film, as described by v (pd/s) greater than 63, is governed by fluid density and surface tension, but is rather independent of viscosity. Finally, the data presented here suggests that a more direct dependence upon the surface tension and viscosity, given a better understanding of their interplay, would allow accurate description of the droplet-surface impacts for more complicated situations involving non-Newtonian fluids, specifically those exhibiting viscoelastic behavior.

Wal, Randy L. Vander↗
DOE OSTI2021

Simulation and analysis of slip flow of water at hydrophobic silica surfaces of nanometer slit pores

Water flow in nanopores is controlled fundamentally by pore wettability and interfacial water features. In the research herein reported, Molecular dynamics (MD) was used to simulate water flow in nanometer slit pores of silica surfaces with variable wetting characteristics. Compared to Couette flow, the simulated slit-pores of the talc (001) and octadecyltrichlorosilane (OTS) monolayer surfaces exhibited water flow enhancement and a positive slip length at the interface, whereas water flow velocity at the quartz (001) and amorphous silica surfaces was zero, adhering to the no slip condition. More intensive interactions between the interfacial water and hydrophilic silica surfaces were confirmed by MD simulation and sum-frequency vibrational spectroscopy (SFVS) results. A water exclusion zone of approximately 3 Å was found at the hydrophobic silica surfaces by quantitative MD interfacial water analysis and validated by SFVS. This exclusion zone dimension was similar in magnitude to the slip length (4–5 Å) as determined from simulated water flow in hydrophobic silica slit pores. The simulated slip lengths at the hydrophobic surfaces (0.2–1 nm) were significantly less than the experimental slip lengths (>40 nm) reported in the literature. In the case of the experimental results, this difference appears to be due to nanobubbles expected to be present at hydrophobic surfaces.

42 ENGINEERING↗
DOE OSTI2019

Determining the Machining Error due to Tool Heating

Principles are outlined for calculating the machining error associated with shift of the cutting edge due to tool heating on cutting. The following factors are taken into account in calculating the temperature at the workpiece surface: the cutting conditions, the tool geometry, and the physicomechanical properties of the workpiece and tool.

42 ENGINEERING↗
DOE OSTI2016

Osteoarthritis-derived chondrocytes are a potential source of multipotent progenitor cells for cartilage tissue engineering

The natural healing capacity of damaged articular cartilage is poor, rendering joint surface injuries a prime target for regenerative medicine. While autologous chondrocyte or mesenchymal stem cell (MSC) implantation can be applied to repair cartilage defects in young patients, no appropriate long-lasting treatment alternative is available for elderly patients with osteoarthritis (OA). Multipotent progenitor cells are reported to present in adult human articular cartilage, with a preponderance in OA cartilage. These facts led us to hypothesize the possible use of osteoarthritis-derived chondrocytes as a cell source for cartilage tissue engineering. We therefore analyzed chondrocyte- and stem cell-related markers, cell growth rate, and multipotency in OA chondrocytes (OACs) and bone marrow-derived MSCs, along with normal articular chondrocytes (ACs) as a control. OACs demonstrated similar phenotype and proliferation rate to MSCs. Furthermore, OACs exhibited multilineage differentiation ability with a greater chondrogenic differentiation ability than MSCs, which was equivalent to ACs. We conclude that chondrogenic capacity is not significantly affected by OA, and OACs could be a potential source of multipotent progenitor cells for cartilage tissue engineering. - Highlights: • Osteoarthritis chondrocytes (OACs) have multilineage differentiation capacity. • Articular chondrocytes (ACs) and OACs have similar gene expression profiles. • OACs have high chondrogenic potential. • OACs could be a cell resource for cartilage tissue engineering.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Low-energy helium plasma effects on textured micro-porous tungsten

The effects of low-energy helium plasma on surface evolution and restructuring of micro-porous tungsten and tungsten-rhenium micro-engineered materials was experimentally investigated. Tungsten foam samples of 45 and 80 Pores Per Inch (PPI) of three types of textured surface architecture (nodular W, dense Re-pillars, and W-coated Re-pillars) were exposed to low-energy helium plasma at 80 and 200 eV to fluence levels of 1, 2, and 7 x 10 25 m -2 at 1123 K. The sidewalls of Re pillars exhibited surface holes due to trapped helium while their tips were found to form complex nano-scale web structures, 100's of microns across, rather than nano-tendrils (fuzz) that are often observed in flat W samples. A nano-necklace bead/string structure was observed for the first time on Re pillars, likely driven by a high density of nano-meter size helium bubbles crowded near pillar tips. W-coated Re pillars exhibited typical fuzz nanostructures seen on flat and untextured W-foam, albeit much shorter. While the height of W-fuzz was found to depend on the square root of ion fluence, the nano-web height was found to be linearly dependent on ion fluence. The fuzz was found to grow much slower on nodular foams as compared to planar tungsten, by as much as 25% slower in the W-coated Re pillar samples. Weight loss due to ion sputtering was found to be significantly reduced in nodular foam as compared to planar tungsten, but was found to be more pronounced with Re pillars. Surface coverage by nano-webs may provide insulation against plasma disruptions and act as a passive Thermal Protection System (TPS) that may be ablated during severe plasma disruptions, thus protecting the underlying surface. W-pillars or W-coated Re-pillars are found to allow trapped helium to diffuse out of the surface instead of building up sub-surface stress.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Photocatalytic Oxidation of Dissolved Mn 2+ by TiO 2 and the Formation of Tunnel Structured Manganese Oxides

The redox reaction of manganese (Mn) is of great environmental, geological, and public health significance, as Mn oxides control the distribution and electron flow of numerous nutrients and contaminants in natural and engineered environments. Current understanding on the oxidation pathways of Mn(II) to Mn(III/IV) mainly focuses on biotic processes due to their much higher oxidation rates than those of abiotic processes. This study demonstrates rapid photocatalytic oxidation of Mn 2+ (aq) under circumneutral conditions catalyzed by naturally abundant semiconducting TiO 2 minerals. Notably, the photocatalytic oxidation rates are comparable to or even higher than those of reported biotic/abiotic processes. In addition, the rapid photocatalytic oxidation leads to the formation of large tunnel structured Mn oxides (todorokite and romanechite) on the surface of TiO 2 . These findings suggest that photocatalytic oxidation of Mn 2+ (aq) by natural semiconducting minerals is likely an important yet previously overlooked pathway for understanding the occurrence of natural Mn oxide coatings on rock surfaces. In addition, considering the increasing input of photoreactive engineered nanoparticles into environmental systems, this work shows the potential impacts of nanoparticles on influencing natural redox cycles.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2007

Delamination-Indicating Thermal Barrier Coatings

The risk of premature failure of thermal barrier coatings (TBCs), typically composed of yttria-stabilized zirconia (YSZ), compromises the reliability of TBCs used to provide thermal protection for turbine engine components. Unfortunately, TBC delamination proceeds well beneath the TBC surface and cannot be monitored by visible inspection. Nondestructive diagnostic tools that could reliably probe the subsurface damage state of TBCs would alleviate the risk of TBC premature failure by indicating when the TBC needs to be replaced before the level of TBC damage threatens engine performance or safety. To meet this need, a new coating design for thermal barrier coatings (TBCs) that are self-indicating for delamination has been successfully implemented by incorporating a europium-doped luminescent sublayer at the base of a TBC composed of YSZ. The luminescent sublayer has the same YSZ composition as the rest of the TBC except for the addition of low-level europium doping and therefore does not alter TBC performance.

Eldridge, Jeffrey I.↗
DOE OSTI2019

Volumetric additive manufacturing via tomographic reconstruction

Additive manufacturing promises enormous geometrical freedom and the potential to combine materials for complex functions. The speed, geometry, and surface quality limitations of additive processes are linked to their reliance on material layering. We demonstrated concurrent printing of all points within a three-dimensional object by illuminating a rotating volume of photosensitive material with a dynamically evolving light pattern. We printed features as small as 0.3 millimeters in engineering acrylate polymers and printed soft structures with exceptionally smooth surfaces into a gelatin methacrylate hydrogel. Our process enables us to construct components that encase other preexisting solid objects, allowing for multimaterial fabrication. We developed models to describe speed and spatial resolution capabilities and demonstrated printing times of 30 to 120 seconds for diverse centimeter-scale objects.

42 ENGINEERING↗
NASA NTRS2003

Capabilities of the Materials Contamination Team at Marshall Space Flight Center

The Materials Contamination Team at the Marshall Space Flight Center (MSFC) has been recognized for its contributions supporting the National Aeronautics and Space Administration (NASA) spacecraft development programs. These programs include the Reusable Solid Rocket Motor (RSRM), Chandra X-Ray Observatory, and the International Space Station (ISS). The Environmental Effects Group, with the Materials Contamination Team and the Space Environmental Effects Team has been an integral part of NASA's success by the testing, evaluation, and qualification of materials, hardware, and processes. This paper focuses on the capabilities of the Materials Contamination Team. The Materials Contamination Team's realm of responsibility includes establishing contamination control during all phases of hardware development, including design, manufacturing, assembly, test, transportation, launch site processing, on-orbit exposure, return, and refurbishment. The team continues its mission of reducing the risk of equipment failure due to molecular or particulate contamination. Contamination is a concern in the Space Shuttle with sensitive bond-lines and reactive fluid (liquid oxygen) compatibility as well as for spacecraft with sensitive optics, such as Hubble Space Telescope and Chandra X-ray Observatory. The Materials Contamination Team has a variety of facilities and instrumentation capable of contaminant detection, identification, and monitoring. The team addresses material applications dealing with environments, including production facilities, clean rooms, and on-orbit exposure. The optically stimulated electron emission (OSEE) system, the Ultraviolet (UV) fluorescence (UVF) surface contamination detection, and the Surface Optics Corporation 400 (SOC 400) portable hand-held Fourier Transform Infrared (FTIR) spectrometer are state-of-the-art tools for in-process molecular contamination detection. The team of engineers and technicians also develop contamination calibration standards and evaluate new surface cleanliness inspection technologies. The team utilizes facilities for on-orbit simulation testing of materials for outgassing and molecular film deposition characteristics in the presence of space environmental effects, such as Atomic Oxygen (AO) and UV radiation exposure. The Materials Contamination Team maintains databases for process materials as well as outgassing and optical compatibility test results for specific environments.

Burns, Howard↗
NASA NTRS2005

Transient Approximation of SAFE-100 Heat Pipe Operation

Engineers at Los Alamos National Laboratory (LANL) have designed several heat pipe cooled reactor concepts, ranging in power from 15 kWt to 800 kWt, for both surface power systems and nuclear electric propulsion systems. The Safe, Affordable Fission Engine (SAFE) is now being developed in a collaborative effort between LANL and NASA Marshall Space Flight Center (NASA/MSFC). NASA is responsible for fabrication and testing of non-nuclear, electrically heated modules in the Early Flight Fission Test Facility (EFF-TF) at MSFC. In-core heat pipes must be properly thawed as the reactor power starts. Computational models have been developed to assess the expected operation of a specific heat pipe design during start-up, steady state operation, and shutdown. While computationally intensive codes provide complete, detailed analyses of heat pipe thaw, a relatively simple. concise routine can also be applied to approximate the response of a heat pipe to changes in the evaporator heat transfer rate during start-up and power transients (e.g., modification of reactor power level) with reasonably accurate results. This paper describes a simplified model of heat pipe start-up that extends previous work and compares the results to experimental measurements for a SAFE-100 type heat pipe design.

Bragg-Sitton, Shannon M.↗
NASA NTRS2007

Feasibility Study of Vapor-Mist Phase Reaction Lubrication Using a Thioether Liquid

A primary technology barrier preventing the operation of gas turbine engines and aircraft gearboxes at higher temperatures is the inability of currently used liquid lubricants to survive at the desired operating conditions over an extended time period. Current state-of-the-art organic liquid lubricants rapidly degrade at temperatures above 300 C; hence, another form of lubrication is necessary. Vapor or mist phase reaction lubrication is a unique, alternative technology for high temperature lubrication. The majority of past studies have employed a liquid phosphate ester that was vaporized or misted, and delivered to bearings or gears where the phosphate ester reacted with the metal surfaces generating a solid lubricious film. This method resulted in acceptable operating temperatures suggesting some good lubrication properties, but the continuous reaction between the phosphate ester and the iron surfaces led to wear rates unacceptable for gas turbine engine or aircraft gearbox applications. In this study, an alternative non-phosphate liquid was used to mist phase lubricate a spur gearbox rig operating at 10,000 rpm under highly loaded conditions. After 21 million shaft revolutions of operation the gears exhibited only minor wear.

Morales, Wilfredo↗
NASA NTRS2024

Synthetic Biology to Support Human Exploration of Deep Space

The International Space Station (ISS) has enabled a continuous human presence in space since November 2000. The ISS is in low Earth orbit, facilitating regular resupply missions to deliver air, water, food, spare parts, and science experiments. NASA’s Moon to Mars campaign seeks to return humans to the Moon and prepare for crewed missions to Mars. Increased distance from Earth poses logistical challenges to provide all resources needed by humans for deep space missions. NASA Ames Research Center is conducting a series of synthetic biology projects to test the use of microbes for on-demand biosynthesis of human micronutrients. The BioNutrients spaceflight experiments test an implementation concept to produce fermented food products in which microbe growth enhances micronutrient content. On-demand production of carotenoids was engineered into two yeast (Saccharomyces cerevisiae) strains that have been tested in nearly 5 years of storage. One of the BioNutrients strains will be incorporated into the Lunar Explorer Instrument for Space Biology Applications (LEIA) project. LEIA is developing an instrument suite to be delivered to the lunar south pole region by the Commercial Lunar Payload Services (CLPS) program. The LEIA instrument suite will be used to measure multiple yeast strains for growth, metabolic activity, and synthetic biology-enabled production of carotenoids, while taking real time measurements of biologically relevant radiation exposure on the lunar surface. LEIA data will be used to assess the impact of lunar surface radiation and reduced gravity on the production of engineered traits.

Synthetic Biology↗
NASA NTRS2014

Modeling the Deterioration of Engine and Low Pressure Compressor Performance During a Roll Back Event Due to Ice Accretion

The main focus of this study is to apply a computational tool for the flow analysis of the engine that has been tested with ice crystal ingestion in the Propulsion Systems Laboratory (PSL) of NASA Glenn Research Center. A data point was selected for analysis during which the engine experienced a full roll back event due to the ice accretion on the blades and flow path of the low pressure compressor. The computational tool consists of the Numerical Propulsion System Simulation (NPSS) engine system thermodynamic cycle code, and an Euler-based compressor flow analysis code, that has an ice particle melt estimation code with the capability of determining the rate of sublimation, melting, and evaporation through the compressor blade rows. Decreasing the performance characteristics of the low pressure compressor (LPC) within the NPSS cycle analysis resulted in matching the overall engine performance parameters measured during testing at data points in short time intervals through the progression of the roll back event. Detailed analysis of the fan-core and LPC with the compressor flow analysis code simulated the effects of ice accretion by increasing the aerodynamic blockage and pressure losses through the low pressure compressor until achieving a match with the NPSS cycle analysis results, at each scan. With the additional blockages and losses in the LPC, the compressor flow analysis code results were able to numerically reproduce the performance that was determined by the NPSS cycle analysis, which was in agreement with the PSL engine test data. The compressor flow analysis indicated that the blockage due to ice accretion in the LPC exit guide vane stators caused the exit guide vane (EGV) to be nearly choked, significantly reducing the air flow rate into the core. This caused the LPC to eventually be in stall due to increasing levels of diffusion in the rotors and high incidence angles in the inlet guide vane (IGV) and EGV stators. The flow analysis indicating compressor stall is substantiated by the video images of the IGV taken during the PSL test, which showed water on the surface of the IGV flowing upstream out of the engine, indicating flow reversal, which is characteristic of a stalled compressor.

Veres, Joseph P.↗