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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

A dynamic subgrid-scale eddy viscosity model

One major drawback of the eddy viscosity subgrid-scale stress models used in large-eddy simulations is their inability to represent correctly with a single universal constant different turbulent field in rotating or sheared flows, near solid walls, or in transitional regimes. In the present work, a new eddy viscosity model is presented which alleviates many of these drawbacks. The model coefficient is computed dynamically as the calculation progresses rather than input a priori. The model is based on an algebraic identity (Germano 1990) between the subgrid-scale stresses at two different filtered levels and the resolved turbulent stresses. The subgrid-scale stresses obtained using the proposed model vanish in laminar flow and at a solid boundary, and have the correct asymptotic behavior in the near-wall region of a turbulent boundary layer. The results of large-eddy simulations of transitional and turbulent channel flow that use the proposed model are in good agreement with the direct simulation data.

Germano, Massimo↗
NASA NTRS1993

Investigation of the asymptotic state of rotating turbulence using large-eddy simulation

Study of turbulent flows in rotating reference frames has long been an area of considerable scientific and engineering interest. Because of its importance, the subject of turbulence in rotating reference frames has motivated over the years a large number of theoretical, experimental, and computational studies. The bulk of these previous works has served to demonstrate that the effect of system rotation on turbulence is subtle and remains exceedingly difficult to predict. A rotating flow of particular interest in many studies, including the present work, is examination of the effect of solid-body rotation on an initially isotropic turbulent flow. One of the principal reasons for the interest in this flow is that it represents the most basic turbulent flow whose structure is altered by system rotation but without the complicating effects introduced by mean strains or flow inhomogeneities. The assumption of statistical homogeneity considerably simplifies analysis and computation. The principal objective of the present study has been to examine the asymptotic state of solid-body rotation applied to an initially isotropic, high Reynolds number turbulent flow. Of particular interest has been to determine the degree of two-dimensionalization and the existence of asymptotic self-similar states in homogeneous rotating turbulence.

Squires, Kyle D.↗
NASA NTRS1995

Analysis of advanced solid rocket motor ignition phenomena

This report presents the results obtained from an experimental analysis of the flow field in the slots of the star grain section in the head-end of the advanced solid rocket motor during the ignition transient. This work represents an extension of the previous tests and analysis to include the effects of using a center port in conjunction with multiple canted igniter ports. The flow field measurements include oil smear data on the star slot walls, pressure and heat transfer coefficient measurements on the star slot walls and velocity measurements in the star slot.

Foster, Winfred A., Jr.↗
NASA NTRS2005

Emerging Sealing Technologies Development

Under this Cooperative Agreement, the objective was to investigate several emerging sealing technologies of interest to the Mechanical Components Branch of National Aeronautics and Space Administration Glenn Research Center at Lewis Field (NASA GRC). The majority of the work conducted was to support the development of Solid Oxide Fuel Cells for application to aeronautic auxiliary power units, though technical investigations of interest to other groups and projects were also conducted. In general, accomplishments and results were periodically reported to the NASA Technical Monitor, the NASA GRC Seal Team staff, and NASA GRC project management. Several technical reports, journal articles, and presentations were given internally to NASA GRC and to the external public.

Source record↗
NASA NTRS2007

The CEOS/GEO Constellation Concept

The Constellation concept was first proposed during a discussion at the 19th CEOS Plenary, in London, in November 2005. The first Paper of the Constellation Concept was presented at the CEOS Strategic Implementation Team meeting (SIT-18), in Frascati, in March 2006, and strongly endorsed by the CEOS Principals. The concept attempts to provide agencies with tools for implementation of the elements that have been previously discussed in international forums (GEO Work Plan, GCOS Implementation Plan). This provides a solid foundation from the community providing requirements. Though agency spending is governed by national requirements, CEOS seeks synergies among member agency programs to fulfil GEOSS requirements, defining guidelines and standards to help agencies to determine from the outset what can be achieved. The constellations concept will allow the development of a commonalties approach among different agencies. At the heart of the application of the Constellations concept is the definition of a series of standards (specific to each Constellation) - required to be satisfied for any mission to be included in the constellation - and a process of recognition/acceptance, whereby an agency applies to SIT to have one or more of its missions (ideally from the outset of planning) recognised as meeting the constellation standards and thereby satisfying the relevant user community needs.

Cramer, Bryant↗
NASA NTRS2011

Progress Towards a Cartesian Cut-Cell Method for Viscous Compressible Flow

The proposed paper reports advances in developing a method for high Reynolds number compressible viscous flow simulations using a Cartesian cut-cell method with embedded boundaries. This preliminary work focuses on accuracy of the discretization near solid wall boundaries. A model problem is used to investigate the accuracy of various difference stencils for second derivatives and to guide development of the discretization of the viscous terms in the Navier-Stokes equations. Near walls, quadratic reconstruction in the wall-normal direction is used to mitigate mesh irregularity and yields smooth skin friction distributions along the body. Multigrid performance is demonstrated using second-order coarse grid operators combined with second-order restriction and prolongation operators. Preliminary verification and validation for the method is demonstrated using flat-plate and airfoil examples at compressible Mach numbers. Simulations of flow on laminar and turbulent flat plates show skin friction and velocity profiles compared with those from boundary-layer theory. Airfoil simulations are performed at laminar and turbulent Reynolds numbers with results compared to both other simulations and experimental data

Berger, Marsha↗
NASA NTRS2014

Microorganism Utilization for Synthetic Milk

A desired architecture for long duration spaceflight, like aboard the International Space Station or for future missions to Mars, is to provide a supply of fresh food crops for the astronauts. However, some crops can create a high proportion of inedible plant waste. The main goal of the Synthetic Biology project, Cow in a Column, was to produce the components of milk (sugar, lipid, protein) from inedible plant waste by utilizing microorganisms (fungi, yeast, bacteria). Of particular interest was utilizing the valuable polysaccharide, cellulose, found in plant waste, to naturally fuel-through microorganism cellular metabolism- the creation of sugar (glucose), lipid (milk fat), and protein (casein) in order to produce a synthetic edible food product. Environmental conditions such as pH, temperature, carbon source, aeration, and choice microorganisms were optimized in the laboratory and the desired end-products, sugars and lipids, were analyzed. Trichoderma reesei, a known cellulolytic fungus, was utilized to drive the production of glucose, with the intent that the produced glucose would serve as the carbon source for milk fat production and be a substitute for the milk sugar lactose. Lipid production would be carried out by Rhodosporidium toruloides, yeast known to accumulate those lipids that are typically found in milk fat. Results showed that glucose and total lipid content were below what was expected during this phase of experimentation. In addition, individual analysis of six fatty acids revealed that the percentage of each fatty acid was lower than naturally produced bovine milk. Overall, this research indicates that microorganisms could be utilized to breakdown inedible solid waste to produce useable products. For future work, the production of the casein protein for milk would require the development of a genetically modified organism, which was beyond the scope of the original project. Additional trials would be needed to further refine the required environment/organisms for the production of desired sugar and lipid end-products.

Microorganisms↗
NASA NTRS2014

GRAIL Refinements to Lunar Seismic Structure

Gravity field measurements are perhaps the most numerous of the indirect observations relevant to the Moon's internal structure. Multiple recent missions have mapped the global lunar gravity field, each one improving upon the resolution of the last. The details of the Moon's deepest structure, including the parameters that define the lunar core, however, were still largely unaddressed by pre-GRAIL gravity measurements, which were not high enough resolution to resolve the tidal coefficients at a sufficient degree of accuracy. Current constraints on core size and state arise from other indirect measurements, including lunar laser ranging, magnetic induction studies, and analyses of elemental abundances in depth-derived mare basalts. These inferences vary widely, but when considered together with structure models derived from the seismic data gathered during the Apollo missions, a schematic of the lunar interior containing a partially molten deepest mantle layer overlying molten outer and solid inner core layers was obtained. Seismology provides the most direct constraints on the variables that govern the dynamic properties of the body. However, the GRAIL mission's high-resolution measurements of the lunar gravity field are being used to constrain the interior structure of the Moon using a "crust to core" approach. GRAIL's constraints on crustal thickness, mantle structure, core radius and stratification, and core state (solid vs. molten) therefore complement seismic investigations. This work focuses on expanding our knowledge of the Moon's internal structure using joint gravity and seismic analyses, which will improve constraints on the deep lunar mantle and core.

Weber, Renee C.↗
DOE OSTI2019

Thermodynamic modeling of the U 3 O 8-x solid solution phase

It is important to accurately characterize the equilibrium behavior of U 3 O 8 during UO 2 nuclear fuel fabrication as the determination of the oxygen to uranium ratio in UO 2 powders and pellets is dependent on U 3 O 8 stoichiometry. Prior thermodynamic modeling efforts have treated U 3 O 8 as stoichiometric; however, it is experimentally known that the phase exhibits hypostoichiometric behavior at temperatures >850 K. The goal of this work was to model U 3 O 8 as a solid solution using the compound energy formalism and optimize the model to experimental data according to the CALPHAD methodology. Results of the U 3 O 8-x model assessment were visualized by recalculating the previously assessed U–O binary phase diagram replacing a stoichiometric representation of U 3 O 8 with a U 3 O 8-x solid solution model. Moreover, a recommendation is made to revise the U 3 O 8 to U conversion factor used in the ASTM C 1453 standard based on the literature and updated thermodynamic representation for U 3 O 8-x presented in this work.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Stable perovskite-fluorite dual-phase composites synthesized by one-pot solid-state reactive sintering for protonic ceramic fuel cells

We report that this work synthesized a series of oxide composites with nominal compositions of BaCe 05 Zr 0.4 Y 0.1 O 3-δ (BCZY)-Ce 0.5 Y 0.5 O 2-δ (YDC) based on the BCZY/YDC molar ratios of 0.5:1, 1:1, 2:1, and 4:1 (BCZY-YDC-0.5–1, BCZY-YDC-1-1, BCZY-YDC-2-1, and BCZY-YDC-4-1) using a one-pot solid state reactive sintering (SSRS) method. The X-ray diffraction (XRD) patterns and refinement proved that the one-pot SSRS at 1450 °C for 12 h could achieve the perovskite-fluorite dual-phase composites (DPCs) with the desired structure compositions. The scanning electron microscopy (SEM) images showed that the two DPCs of BCZY-YDC-1-1 and BCZY-YDC-2-1 formed excellent percolation for perovskite and fluorite phases. The conductivity measurement by electrochemical impedance spectroscopy (EIS) and the transference number measurement by the electromotive force (EMF) test proved that changing the BCZY/YDC molar ratio and operating condition could adjust the DPC's conduction property to make them suitable for electrolytes and electrode scaffolds for protonic ceramic fuel cells (PCFCs). The long-term conductivity testing and the crystal structure analysis after EMF testing under versatile conditions indicated that the DPCs of BCZY-YDC-2-1 and BCZY-YDC-1-1 were durable PCFC component materials. The PCFC button cells with the as-discovered BCZY-YDC-2-1 and BCZY-YDC-1-1 as an electrolyte and an anode scaffold, respectively, and the reported Ba–Ce–Fe–Co–O perovskite-perovskite composite as a cathode showed promising performance under H 2 /air gradient.

08 HYDROGEN↗
NASA NTRS1995

Analysis of measurements for solid state laser remote lidar system

The merits of using lidar systems for remote measurements of various atmospheric processes such as wind, turbulence, moisture, and aerosol concentration are widely recognized. Although the lidar technology has progressed considerably over the past two decades, significant research particularly in the area of solid state lidars remains to be conducted in order to fully exploit this technology. The work performed by the UAH (University of Alabama in Huntsville) personnel under this Delivery Order concentrated on analyses of measurements required in support of solid state laser remote sensing lidar systems which are to be designed, deployed, and used to measure atmospheric processes and constituents. UAH personnel has studied and recommended to NASA/MSFC the requirements of the optical systems needed to characterize the detection devices suitable for solid state wavelengths and to evaluate various heterodyne detection schemes. The 2-micron solid state laser technology was investigated and several preliminary laser designs were developed and their performance for remote sensing of atmospheric winds and clouds from a spaceborne platform were specified. In addition to the laser source and the detector, the other critical technologies necessary for global wind measurements by a spaceborne solid state coherent lidar systems were identified to be developed and demonstrated. As part of this work, an analysis was performed to determine the atmospheric wind velocity estimation accuracy using the line-of-sight measurements of a scanning coherent lidar. Under this delivery order, a computer database of materials related to the theory, development, testing, and operation of lidar systems was developed to serve as a source of information for lidar research and development.

Amzajerdian, Farzin↗
DOE OSTI2019

Li 15 P 4 S 16 Cl 3 , a Lithium Chlorothiophosphate as a Solid-State Ionic Conductor

Tremendous efforts have been devoted to the design of solid Li + electrolytes and the development of all-solid-state batteries. Compared with conventional Li-ion batteries, which use flammable liquid organic electrolytes, all-solid-state batteries show significant advantages in safety. In this work, a novel lithium chlorothiophosphate compound, Li 15 P 4 S 16 Cl 3 , is discovered. The crystal structure and electrochemical properties are investigated. Li 15 P 4 S 16 Cl 3 can be synthesized as a pure phase via a facile solid-state reaction by heating a ball-milled mixture of Li 2 S, P 2 S 5 , and LiCl at 360 °C. The crystal structure of Li 15 P 4 S 16 Cl 3 was refined against neutron and synchrotron powder X-ray diffraction data, revealing that it crystallizes in the space group $I\bar{4}3d$. Furthermore, the Li + transport in Li 15 P 4 S 16 Cl 3 was also investigated by multiple solid-state NMR methods, including variable-temperature NMR line-shape analysis, NMR relaxometry, and pulsed-field-gradient NMR. Li 15 P 4 S 16 Cl 3 shows good thermodynamic stability and can be synthesized at relatively low temperature. Although it exhibits a low ionic conductivity at room temperature, it can serve as a new motif crystal structure for the design and development of new solid-state electrolytes.

25 ENERGY STORAGE↗
DOE OSTI2022

Identification of efficient and stable solid-solid electrochemical interfaces for Li-S batteries. Final Report

The objective of this work is to develop a better understanding of the interactions between battery components that drive the observed battery performance. Using computational tools at the atomistic level, we elucidate molecular, crystal, and amorphous structures, interfacial structures and reactions, and electrochemical behavior. We focus on Li metal anodes, liquid electrolytes, solid electrolytes, S cathodes, and metal-oxide cathodes, and their corresponding interfaces. Within liquid electrolytes, we study their bulk structure and dynamics, as a function of salt concentration. The analysis allows to understand the formation of localized high concentrated regions as the solvent is substituted by a weakly interacting diluent species. Analysis of the electron distribution yields the reactive behavior at interfaces. Moreover, we employ tools that allow the characterization of ion and electron transport at interfaces, during the processes of solvation and desolvation occurring while cycling. For Sulfur cathodes we elucidate synthesis processes and the role of carbon-sulfur and nitrogen-sulfur interactions not only to provide electronic conductivity but also to define alternative reaction pathways during discharge of Li-S batteries. Full-cell simulations offer new insights regarding the integration of all the battery components. Our studies also include solid electrolytes and their interfaces with Li metal, S-C, and metal-oxide electrodes.

25 ENERGY STORAGE↗
DOE OSTI2022

Practically Accessible All-Solid-State Batteries Enabled by Organosulfide Cathodes and Sulfide Electrolytes

The combination of organic electrode materials and sulfide electrolytes is expected to enable the development of all-solid-state organic batteries featuring high energy density and long-term sustainability. In this work, thiuram hexasulfide is reported as a low-cost and high-capacity organic cathode for solid-state batteries based on sulfide electrolytes, delivering a capacity of ~600 mAh g -1 and retaining 80.8 % capacity after 500 cycles. An electrochemically reversible change of the cathode interface was revealed upon cycling. Full cell displays an oscillating stress change up to 0.6 MPa during cycling, predominated by the anode side. The energy density is 1140 Wh kg -1 at the material level and 376 Wh kg -1 at the electrode level, which are among the best-reported organic cathodes to date. A high areal capacity of 10.4 mAh cm -2 is reached with a high mass loading cathode. A dry-film approach is further explored to manufacture sheet-type cells. Free-standing electrolyte film is merely ~48 μm thick and demonstrates an ultralow areal resistance of 3.9 Ω cm 2 , significantly boosts the cell-level energy density and reduces the cell internal resistance.

25 ENERGY STORAGE↗
DOE OSTI2019

High-Field Magic Angle Spinning Dynamic Nuclear Polarization Using Radicals Created by γ-Irradiation

High-field magic angle spinning dynamic nuclear polarization (MAS DNP) is often used to enhance the sensitivity of solid-state nuclear magnetic resonance experiments by transferring spin polarization from electron spins to nuclear spins. In this work, we demonstrate that γ-irradiation induces the formation of stable radicals in inorganic solids, such as fused quartz and borosilicate glasses, as well as organic solids, such as glucose, cellulose, and a urea/polyethylene polymer. The radicals were then used to polarize 29 Si or 1 H spins in the core of some of these materials. Significant MAS DNP enhancements (ε) of more than 400 and 30 were obtained for fused quartz and glucose, respectively. For other samples, negligible values of ε were obtained, likely due to low concentrations of radicals or the presence of abundant quadrupolar spins. These results demonstrate that ionizing radiation is an enticing alternative method for generating stable radicals that are suitable for high-field MAS DNP experiments.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Modulating physicochemical interfaces enables li-rich oxides based ceramic solid-state li batteries under ambient conditions

Li-rich layered oxides exhibit promising potential applications in high-energy-density solid-state lithium metal batteries. Nevertheless, the strong oxidative oxygen species generate at high voltage, which poses great challenges to positive electrode-side interface stability. Herein, a robust in-situ polymerization gel polymer electrolyte with bifunctional additives is designed for interface modification. These additives, include lithium difluoro(oxalate) borate and LiPO 2 F 2 , regulate the Li + chemical environment in gel polymer electrolyte to enhance crosslink density without residual oligomer, which reduce gas generation and suppress contact loss, thus avoiding interfacial impedance divergence. Concurrently, the designed gel polymer electrolyte enables a wide electrochemical stability window (up to 4.7 V) and a high Li + transference number (0.82). Additionally, the additives induced F- and B-rich inorganic cathode-electrolyte interphase inhibits side reactions and oxygen/transition metal loss effectively, stabilizing the chemical interface. The as-constructed Li-rich layered oxides-based ceramic solid-state lithium metal batteries with gel polymer electrolyte interface modification exert a high discharge capacity of 276.5 mAh g -1 at 30 °C without external pressure, delivering a retention of 81.7% after 100 cycles at 25 mA g -1 during 2.0-4.7 V. This work provides a guideline for developing high-voltage solid-state lithium metal batteries via interfacial design.

Hu, Xinchao [Xiamen University (China)]↗
NASA NTRS2009

Investigating Liquid CO2 as a Coolant for a MTSA Heat Exchanger Design

Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed for thermal and carbon dioxide (CO 2) control for a future Portable Life Support System (PLSS), as well as water recycling. CO 2 removal and rejection is accomplished by driving a sorbent through a temperature swing of approximately 210 K to 280 K . The sorbent is cooled to these sub-freezing temperatures by a Sublimating Heat Exchanger (SHX) with liquid coolant expanded to sublimation temperatures. Water is the baseline coolant available on the moon, and if used, provides a competitive solution to the current baseline PLSS schematic. Liquid CO2 (LCO2) is another non-cryogenic coolant readily available from Martian resources which can be produced and stored using relatively low power and minimal infrastructure. LCO 2 expands from high pressure liquid (~5800 kPa) to Mars ambient (0.8 kPa) to produce a gas / solid mixture at temperatures as low as 156 K. Analysis and experimental work are presented to investigate factors that drive the design of a heat exchanger to effectively use this sink. Emphasis is given to enabling efficient use of the CO 2 cooling potential and mitigation of heat exchanger clogging due to solid formation. Minimizing mass and size as well as coolant delivery are also considered. The analysis and experimental work is specifically performed in an MTSA-like application to enable higher fidelity modeling for future optimization of a SHX design. In doing so, the work also demonstrates principles and concepts so that the design can be further optimized later in integrated applications (including Lunar application where water might be a choice of coolant).

Paul, Heather L.↗
DOE OSTI2025

Solid structure of Li 2 BeF 4 (FLiBe) from room temperature to melting studied by neutron and X-ray diffraction

Molten fluoride salts such as Li 2 BeF 4 (FLiBe) are used in molten salt reactors, fluoride-salt-cooled high-temperature reactors and fusion reactors as a fuel solvent, coolant and/or tritium breeding medium. In engineered systems that use molten salt, solid-state material will be present during melting and freezing scenarios, and therefore the temperature-dependent properties of the solid and solid/liquid phase transition merit investigation. To observe the behavior of the solid state of Li 2 BeF 4 from room temperature to melting, this work used neutron and X-ray diffraction to measure the changes in the lattice parameters and volume of the crystalline unit cell and compared the results with prior low-temperature data for solid Li 2 BeF 4 . From neutron diffraction data it is also possible to identify anisotropy: centimetre-scaled crystals align preferentially with the a axes parallel to the direction of freezing front propagation, and the c axes expand 54% more than the a axes. This work provides the lattice constants as a function of temperature, quantifies the thermal expansion, and determines the equation describing the change in density for solid Li 2 BeF 4 from room temperature to 459°C to be ρ solid (kg m −3 ) = 2182 (3) − 0.115 (2) T (°C) and the volume expansion upon melting to be less than 5%. This density changes depending on molecular weight and enrichment.

36 MATERIALS SCIENCE↗