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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Foundation, excavation and radiation shielding concepts for a 16-m large lunar telescope

NASA is considering a 16-m diameter optical telescope on the moon as a part of the Space Exploration Initiative. Fundamental concepts of engineering activities on the moon and how they can be applied to the establishment of a 16-m large lunar telescope (LLT) are discussed. These fundamental concepts include the engineering response of lunar soils and how they affect construction activities, namely, drilling, blasting, ripping, digging and compaction. A mirror support structure and foundation design concept is proposed. The foundation considered is a multiple contact points spud-can type footing. It does not appear that a deep foundation or the presence of bedrock is required to achieve the telescope foundation stiffness. The LLT system will include a regolith covered housing, the size of a small room, which will contain sensitive electronic equipment including charge coupled devices which need protection from cosmic radiation effects. A brief discussion is made on radiation, radiation transport and radiation effects on electronics and on humans. Radiation protection techniques and the different emplacement schemes for the LLT instrument housing for radiation protection are suggested. A structural concept of an early lunar based telescope is also presented.

Chua, Koon M.↗
NASA NTRS1991

Experimental validation of docking and capture using space robotics testbeds

This presentation describes the application of robotic and computer vision systems to validate docking and capture operations for space cargo transfer vehicles. Three applications are discussed: (1) air bearing systems in two dimensions that yield high quality free-flying, flexible, and contact dynamics; (2) validation of docking mechanisms with misalignment and target dynamics; and (3) computer vision technology for target location and real-time tracking. All the testbeds are supported by a network of engineering workstations for dynamic and controls analyses. Dynamic simulation of multibody rigid and elastic systems are performed with the TREETOPS code. MATRIXx/System-Build and PRO-MATLAB/Simulab are the tools for control design and analysis using classical and modern techniques such as H-infinity and LQG/LTR. SANDY is a general design tool to optimize numerically a multivariable robust compensator with a user-defined structure. Mathematica and Macsyma are used to derive symbolically dynamic and kinematic equations.

Spofford, John↗
NASA NTRS2004

International GPS Service 2001 - 2002 Technical Reports

Applications of the Global Positioning System (GPS) to Earth Science are numerous. The International GPS Service (IGS), a federation of government agencies and universities, plays an increasingly critical role in support of GPS-related research and engineering activities. Contributions from the IGS Governing Board and Central Bureau, analysis and data centers, station operators, and others constitute the 2001 / 2002 Technical Reports. Hard copies of each volume can be obtained by contacting the IGS Central Bureau at the Jet Propulsion Laboratory. This report is published in black and white. To view graphs or plots that use color to represent data trends or information, please refer to the online PDF version at http://igscb.jpl.nasa.gov/overview/pubs.html.

Gowey, Ken↗
NASA NTRS2012

Lunar Crater Mini-Wakes: Structure, Variability, and Volatiles

Within a permanently shadowed lunar crater the horizontal flow of solar wind is obstructed by upstream topography, forming a regional plasma mini-wake. In the present work kinetic simulations are utilized to investigate how the most prominent structural aspects of a crater mini-wake are modulated during passage of a solar storm. In addition, the simulated particle fluxes are coupled into an equivalent-circuit model of a roving astronaut,. including triboelectric charging due to frictional contact with the lunar regolith, to characterize charging of the astronaut suit during the various stages of the storm. In some cases, triboelectric charging of the astronaut suit becomes effectively perpetual, representing a critical engineering concern for roving within shadowed lunar regions. Finally, the present results suggest that wake structure plays a critical role in modulating the spatial distribution of volatiles at the lunar poles.

Zimmerman, Michael I.↗
NASA NTRS2015

Techniques for Measuring Surface Potentials in Space

Materials exposed to the space plasma environment charge to a net potential relative to the ambient plasma. The charging process is due to differential currents to the material surface that results in a net surface charge density. While this process is termed "spacecraft surface charging" when applied to aerospace hardware, it also applies to the surfaces of astronomical objects in direct contact with the space plasma environment including a number of planetary bodies, asteroids, and dust particles. The ability to measure surface potentials is important to many techniques used in conducting fundamental heliospheric science, spacecraft engineering operations, and space technology development activities. This presentation provides a survey of current technologies used to measure surface potentials of spacecraft and planetary bodies with examples of their application to space science and technology programs.

Minow, Joseph I.↗
DOE OSTI2020

Elevated temperature mechanical properties of Inconel 617 surface oxide using nanoindentation

Inconel 617 is a principal candidate material for helium gas cooled very-high-temperature reactors with outlet temperatures of 700–950 °C. Recent findings showed that this alloy develops unique surface oxide layers especially at high temperature (HT) helium environment with distinctive wear, friction and contact properties. This study investigates the elevated temperature mechanical properties of Inconel 617 top surface layers aged in HT helium environment. Nanoindentation technique is used to obtain load-displacement graphs of the alloy top surface oxide in temperatures ranging from 25 °C up to 600 °C. In addition, using finite element analysis along with an iterative regression technique, a semi-numerical method is developed to further measure and quantify the material parameters and, in particular, time-independent and creep characteristics of the oxide. Although Young's modulus of the oxide is found to be relatively close to the bulk for the tested temperatures, the yield strength and hardness, in comparison to the bulk material, increase significantly as the material is oxidized after aging. The oxide exhibits significant softening as the temperature increases to 600 °C. Unlike the bulk material, diffusion through the grains is found to be the dominant creep mechanism for the oxide. Considerable difference between the mechanical properties of the oxide and the bulk material shows the need for accurate measurements of near surface mechanical properties, if reliable predictive contact and tribological models are sought at elevated temperatures.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Solder hermetic sealing for OLEDs

An OLED device comprising a substrate with a top surface; a first electrode covering the top surface of the substrate; a first insulating structure patterned over a portion of the first electrode where the pattern defines an inside area of the first electrode that is completely surrounded by the insulating structure, and an outside area of the first electrode not covered by the insulating structure; at least one organic layer for light emission within the inside area defined by the insulating structure; a second electrode over the at least one organic layer within the inside area defined by the insulating structure and at least partially over the first insulating structure; a cover slip located at least over the second electrode in the inside area defined by the insulating structure; and an electrically conductive solder seal making a hermetic seal between the insulating structure and the cover slip where the solder seal is in electrical contact with the second electrode. The insulating structure is desirably made of glass frit.

42 ENGINEERING↗
NASA NTRS1993

Liquid propellant rocket engine combustion simulation with a time-accurate CFD method

Time-accurate computational fluid dynamics (CFD) algorithms are among the basic requirements as an engineering or research tool for realistic simulations of transient combustion phenomena, such as combustion instability, transient start-up, etc., inside the rocket engine combustion chamber. A time-accurate pressure based method is employed in the FDNS code for combustion model development. This is in connection with other program development activities such as spray combustion model development and efficient finite-rate chemistry solution method implementation. In the present study, a second-order time-accurate time-marching scheme is employed. For better spatial resolutions near discontinuities (e.g., shocks, contact discontinuities), a 3rd-order accurate TVD scheme for modeling the convection terms is implemented in the FDNS code. Necessary modification to the predictor/multi-corrector solution algorithm in order to maintain time-accurate wave propagation is also investigated. Benchmark 1-D and multidimensional test cases, which include the classical shock tube wave propagation problems, resonant pipe test case, unsteady flow development of a blast tube test case, and H2/O2 rocket engine chamber combustion start-up transient simulation, etc., are investigated to validate and demonstrate the accuracy and robustness of the present numerical scheme and solution algorithm.

Chen, Y. S.↗
DOE OSTI2024

Unraveling electrochemo-mechanical aspects of core–shell composite cathode for sulfide based all-solid-state batteries

All-solid-state lithium batteries (ASSLBs) are emerging as promising next-generation batteries for electric vehicles owing to their high energy densities and safety features. However, challenges such as inadequate material percolation and low cathode utilization often hinder their potential. This paper presents a core–shell approach to optimize the cathode active material (CAM) utilization. The resultant CAM composite showed high ionic conductivity, a highly dense microstructure with <10% porosity, and minimal stack pressure changes during electrochemical cycling. The maximum CAM utilization was achieved while effectively mitigating electrochemo-mechanical side reactions by applying a uniformly coated Li 6 PS 5 Cl solid electrolyte layer (≈500 nm) and a LiNbO 3 buffer layer (≈10 nm) onto LiNi 0.8 Mn 0.1 Co 0.1 O 2 particles (LPSCl@LNO@NMC). The engineered LPSCl@LNO@NMC composites, which incorporated a 5 wt% LPSCl coating on LNO@NMC powders, exhibited a dense microstructure that enhanced the mechanical stability at the cathode. Sulfide-based solid electrolyte (SSE)/SSE contact provided better ionic pathways within the composite and increased CAM utilization. Thus, an enhanced reversible capacity (197 mA h g -1 ) and exceptional high-rate cycling performance (86.3% capacity retention after 1000 cycles at 2C) were observed. These findings pave the way for the advancement and commercialization of high-performance ASSLBs.

25 ENERGY STORAGE↗
NASA NTRS1978

Development of surface coatings for air-lubricated, compliant journal bearings to 650 C

Surface coatings for an air-lubricated, compliant journal for an automotive gas turbine engine were tested to find those capable of withstanding temperatures of either 540 C (1000 F) or 650 C (1200 F). Also, the coatings have to be capable of surviving the start-stop sliding contact cycles prior to rotor lift-off and at touchdown. Selected coating combinations were tested in start-stop tests at 14 kPa (2 psi) loading for 2000 cycles at room and maximum temperatures. Specific coating recommendations are: Cdo and graphite on foil versus chrome carbide on journal up to 370 C (700 F); NASA PS-120 (Tribaloy 400, silver, and CaF2) on journal versus uncoated foil up to 540 C (1000 F); and chemically adherent Cr2O3 on journal and foil up to 650 C (1200 F). The chemically adherent Cr2O3 coating system was further tested successfully at 35 kPa (5 psi) loading for 2000 start-stop cycles.

Bhushan, B.↗
NASA NTRS1991

Alignment Tool For Inertia Welding

Compact, easy-to-use tool aligns drive bar of inertia welder over hole in stub. Ensures drive bar concentric to hole within 0.002 in. (0.051 mm.). Holds two batteries and light bulb. Electrical circuit completed, providing current to bulb when pin in contact with post. When pin centered in post hole, it does not touch post, and lamp turns off. Built for use in making repair welds on liquid-oxygen-injector posts in Space Shuttle main engine. Version having suitably modified dimensions used to facilitate alignment in other forests of post.

Snyder, Gary L.↗
NASA NTRS2012

Automation and Process Improvement Enables a Small Team to Operate a Low Thrust Mission in Orbit Around the Asteroid Vesta

NASA's Dawn mission to the asteroid Vesta and dwarf planet Ceres launched September 27, 2007 and arrived at Vesta in July of 2011. This mission uses ion propulsion to achieve the necessary delta-V to reach and maneuver at Vesta and Ceres. This paper will show how the evolution of ground system automation and process improvement allowed a relatively small engineering team to transition from cruise operations to asteroid operations while maintaining robust processes. The cruise to Vesta phase lasted almost 4 years and consisted of activities that were built with software tools, but each tool was open loop and required engineers to review the output to ensure consistency. Additionally, this same time period was characterized by the evolution from manually retrieved and reviewed data products to automatically generated data products and data value checking. Furthermore, the team originally took about three to four weeks to design and build about four weeks of spacecraft activities, with spacecraft contacts only once a week. Operations around the asteroid Vesta increased the tempo dramatically by transitioning from one contact a week to three or four contacts a week, to fourteen contacts a week (every 12 hours). This was accompanied by a similar increase in activity complexity as well as very fast turn around activity design and build cycles. The design process became more automated and the tools became closed loop, allowing the team to build more activities without sacrificing rigor. Additionally, these activities were dependent on the results of flight system performance, so more automation was added to analyze the flight data and provide results in a timely fashion to feed the design cycle. All of this automation and process improvement enabled up the engineers to focus on other aspects of spacecraft operations, including spacecraft health monitoring and anomaly resolution.

ground system automation↗
NASA NTRS1989

Space Shuttle Main Engine structural analysis and data reduction/evaluation. Volume 2: High pressure oxidizer turbo-pump turbine end bearing analysis

The high-pressure oxidizer turbopump (HPOTP) consists of two centrifugal pumps, on a common shaft, that are directly driven by a hot-gas turbine. Pump shaft axial thrust is balanced in that the double-entry main inducer/impeller is inherently balanced and the thrusts of the preburner pump and turbine are nearly equal but opposite. Residual shaft thrust is controlled by a self-compensating, non-rubbing, balance piston. Shaft hang-up must be avoided if the balance piston is to perform properly. One potential cause of shaft hang-up is contact between the Phase 2 bearing support and axial spring cartridge of the HPOTP main pump housing. The status of the bearing support/axial spring cartridge interface is investigated under current loading conditions. An ANSYS version 4.3, three-dimensional, finite element model was generated on Lockheed's VAX 11/785 computer. A nonlinear thermal analysis was then executed on the Marshall Space Flight Center Engineering Analysis Data System (EADS). These thermal results were then applied along with the interference fit and bolt preloads to the model as load conditions for a static analysis to determine the gap status of the bearing support/axial spring cartridge interface. For possible further analysis of the local regions of HPOTP main pump housing assembly, detailed ANSYS submodels were generated using I-DEAS Geomod and Supertab (Appendix A).

Sisk, Gregory A.↗
DOE OSTI2021

Shocked Transport: Experiments to Study Dynamic Particle Behavior under Varying Volume Fraction Conditions

Shocks interacting with densely-packed porous media is common in volcanic eruptions or in engineering applications such as ordinance. Large-scale, exploratory experiments have been performed by Frost and collaborators examining the behavior of a bed of particles subjected to a detonation wave. The detonation replaces the central explosive with a high-density, high-temperature gas that propagates outward. A shock wave travels through the particle bed, followed by a contact discontinuity between the shocked air and the explosive products. In the early times, the detonation wave causes many of the particles to collide and compact with each other. As the particles disperse, the experiments demonstrate a series of large-scale jets or fingers that form in the advancing particle front.

42 ENGINEERING↗
DOE OSTI2022

Measurement of Piston Deposit Thickness Using Laser Profilometer

In this work, a novel method of measuring the thickness of deposits on engine pistons, including within ring grooves, is described. A laser profilometer is used in conjunction with a rotary stage to measure a continuous profile of the piston with deposits, and the measurement is repeated after cleaning the deposits from the piston. Algorithms for aligning the scans and determining the differential thickness are described, and results are compared to deposit thickness measurements using a contact-type magnetic induction coating thickness gauge. This method allows continuous measurement of deposit thickness across the entire surface including lands and ring grooves as well as quantification of the volume of the deposits.

42 ENGINEERING↗