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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Computational fluid dynamics '92; Proceedings of the European Computational Fluid Dynamics Conference, 1st, Brussels, Belgium, Sep. 7-11, 1992. Vols. 1 & 2

A conference was held on Computational Fluid Dynamics (CFD) and produced related papers. Topics included CFD algorithms, transition and turbulent flow, hypersonic reacting flow, incompressible flow, two phase flow and combustion, internal flow, compressible flow, grid generation and adaption, boundary layers, environmental and industrial applications, and non-Newtonian flow.

Hirsch, Charles↗
NASA NTRS2001

High Pressure, Transport Properties of Fluids: Theory and Data from Levitated Fluid-Drops at Combustion-Relevant Temperatures

The objective of this investigation is to derive a set of consistent mixing rules for calculating diffusivities and thermal diffusion factors over a thermodynamic regime encompassing the subcritical and supercritical ranges. These should serve for modeling purposes, and therefore for accurate simulations of high pressure phenomena such as fluid disintegration, turbulent flows and sprays. A particular consequence of this work will be the determination of effective Lewis numbers for supercritical conditions, thus enabling the examination of the relative importance of heat and mass transfer at supercritical pressures.

Bellan, J.↗
NASA NTRS2003

Fluid shear stress inhibits TNF-alpha-induced apoptosis in osteoblasts: a role for fluid shear stress-induced activation of PI3-kinase and inhibition of caspase-3

In bone, a large proportion of osteoblasts, the cells responsible for deposition of new bone, normally undergo programmed cell death (apoptosis). Because mechanical loading of bone increases the rate of new bone formation, we hypothesized that mechanical stimulation of osteoblasts might increase their survival. To test this hypothesis, we investigated the effects of fluid shear stress (FSS) on osteoblast apoptosis using three osteoblast cell types: primary rat calvarial osteoblasts (RCOB), MC3T3-E1 osteoblastic cells, and UMR106 osteosarcoma cells. Cells were treated with TNF-alpha in the presence of cyclohexamide (CHX) to rapidly induce apoptosis. Osteoblasts showed significant signs of apoptosis within 4-6 h of exposure to TNF-alpha and CHX, and application of FSS (12 dyne/cm(2)) significantly attenuated this TNF-alpha-induced apoptosis. FSS activated PI3-kinase signaling, induced phosphorylation of Akt, and inhibited TNF-alpha-induced activation of caspase-3. Inhibition of PI3-kinase, using LY294002, blocked the ability of FSS to rescue osteoblasts from TNF-alpha-induced apoptosis and blocked FSS-induced inhibition of caspase-3 activation in osteoblasts treated with TNF-alpha. LY294002 did not, however, prevent FSS-induced phosphorylation of Akt suggesting that activation of Akt alone is not sufficient to rescue cells from apoptosis. This result also suggests that FSS can activate Akt via a PI3-kinase-independent pathway. These studies demonstrate for the first time that application of FSS to osteoblasts in vitro results in inhibition of TNF-alpha-induced apoptosis through a mechanism involving activation of PI3-kinase signaling and inhibition of caspases. FSS-induced activation of PI3-kinase may promote cell survival through a mechanism that is distinct from the Akt-mediated survival pathway. Copyright 2002 Wiley-Liss, Inc.

Non-NASA Center↗
NASA NTRS2004

Numerical, Analytical, Experimental Study of Fluid Dynamic Forces in Seals: Description of Incompressible Fluid Seal Codes ICYL and IFACE - Volume 4

The objectives of the program were to develop computational fluid dynamics (CFD) codes and simpler industrial codes for analyzing and designing advanced seals for air-breathing and space propulsion engines. The CFD code SCISEAL is capable of producing full three-dimensional flow field information for a variety of cylindrical configurations. An implicit multidomain capability allow the division of complex flow domains to allow optimum use of computational cells. SCISEAL also has the unique capability to produce cross-coupled stiffness and damping coefficients for rotordynamic computations. The industrial codes consist of a series of separate stand-alone modules designed for expeditious parametric analyses and optimization of a wide variety of cylindrical and face seals. Coupled through a Knowledge-Based System (KBS) that provides a user-friendly Graphical User Interface (GUI), the industrial codes are PC based using an OS/2 operating system. These codes were designed to treat film seals where a clearance exists between the rotating and stationary components. Leakage is inhibited by surface roughness, small but stiff clearance films, and viscous pumping devices. The codes have demonstrated to be a valuable resource for seal development of future air-breathing and space propulsion engines.

Liang, Anita D.↗
NASA NTRS2004

High Temperature mechanically pumped fluid loop for space applications - working fluid selection

Mechanically pumped single-phase fluid loops are increasingly being used for heat rejection purposes in space applications. Examples of Earth orbiting missions using this technology include NSTS Shuttles (water and Freon-based loops) and the International Space Station (water and ammonia-based loops). For deep space missions, both the Mars Pathfinder (1996) and Mars Exploration Rover (2003) missions used mechanically pumped Freon-I 1 loops for their primary Heat Rejection Systems (HRS.) Mechanically pumped loops are particularly well suited for rejecting large amounts of waste heat from spacecraft and future missions incorporating components with extremely high thermal energy dissipation (e.g. radar instruments, Radioisotope-based power sources) are ideal candidates for their use. However, previous implementations of mechanically pumped loops were designed for moderate temperatures (below 6OOC) and, thus, would require relatively large radiators to reject high heat loads to space. Loops designed for a higher operating temperature would allow large amounts of heat to be rejected within the constraints of a mass efficient thermal control system.

high temperature↗
DOE OSTI2016

Investigation of Shear-Thinning Behavior on Film Thickness and Friction Coefficient of Polyalphaolefin Base Fluids With Varying Olefin Copolymer Content

This study investigates the rheological properties, elastohydrodynamic (EHD) film-forming capability, and friction coefficients of low molecular mass poly-alpha-olefin (PAO) base stocks with varying contents of high molecular mass olefin copolymers (OCPs) to assess their shear stability and their potential for energy-efficient lubrication. Several PAO-OCP mixtures were blended in order to examine the relationship between their additive content and tribological performance. Gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy were used to characterize the molecular masses and structures, respectively. Density, viscosity, EHD film thickness, and friction were measured at 303 K, 348 K, and 398 K. Film thickness and friction were studied at entrainment speeds relevant to the boundary, mixed, and full-film lubrication regimes. The PAO-OCP mixtures underwent temporary shear-thinning resulting in decreases in film thickness and hydrodynamic friction. These results demonstrate that the shear characteristics of PAO-OCP mixtures can be tuned with the OCP content and provide insight into the effects of additives on EHD characteristics.

Elastohydrodynamic lubrication↗
DOE OSTI2019

Western USA Assessment of High Value Materials in Geothermal Fluids and Produced Fluids

This report documents the results of investigations dealing with the concentrations and availabilities of strategic, critical and valuable materials (SCVM) in produced waters from geothermal and hydrocarbon reservoirs (50-250° C) in Idaho, Nevada, New Mexico, Oregon, and Utah. Analytical results were obtained for water samples from 47 production wells in 12 geothermal fields. Results were also obtained for samples from 25 oil/gas production wells in the Uinta and Paradox Basins and Covenant oil field, from 14 groundwater wells in the Tularosa play fairway (New Mexico), and from 20 groundwater wells and hot springs in the Sevier Thermal Belt (southwestern Utah). Most SCVM concentrations in produced waters range from <0.1 to 100 ug/kg. Lithium is the only element, which has much higher concentrations and which ranges from 10 to 26,000 ug/kg. Relatively high concentrations of gallium (10-80 ug/kg geothermal; 10-10,000 ug/kg Uinta Basin), germanium (1-70 ug/kg geothermal; 10-500 ug/kg Uinta and Paradox Basins), scandium (0.1-2.0 ug/kg geothermal; 5-10 ug/kg Paradox Basin), selenium (1-100 ug/kg geothermal; 10-20,000 ug/kg Uinta and Paradox Basins), and tellurium (0.1-10 ug/kg geothermal; 1-500 ug/kg Uinta and Paradox Basins) are measured too. Geothermal production waters contain very low concentrations of REEs, below analytical detections limits of 0.01 ug/kg, but the concentrations of some REEs (lanthanum, cerium, and europium) range from 0.05 to 5 ug/kg in Uinta Basin waters. Among the geothermal fields, the Roosevelt Hot Spring reservoir appears to have the largest endowments of germanium (20,000 kg) and lithium (7 million kg), the Patua reservoir appears to have the largest endowments of gallium (25,000 kg), selenium (47,000 kg), and tellurium (2500 kg), and the Raft River reservoir appears to have the large endowment of scandium (700 kg). By comparison, the Uinta Basin has larger inventories of gallium (>100,000 kg). These estimates are provisional, and they were calculated using geologically reasonable values for reservoir volumes and porosities. The concentrations of gallium, germanium, lithium, scandium, selenium, and tellurium in produced waters appear to be partly controlled by reservoir temperature and concentrations of total dissolved salts. The relatively high concentration and large endowment of lithium occurring at Roosevelt Hot Springs appears to be related to hot water interaction with crystalline granitic rocks, which host the reservoir and the hydrothermal system, and elevated concentrations of TDS. Analyses of calcite scales from Dixie Valley show that cobalt, gallium, gold, palladium, selenium and tellurium are depositing at deep levels in production wells due to boiling. Comparisons with SCVM mineral deposits suggest that brines in sedimentary basins or derived from lacustrine evaporites enable aqueous transport of gallium, germanium, and lithium.

15 GEOTHERMAL ENERGY↗
DOE OSTI2017

Anisotropic fluid dynamics for Gubser flow

Investigating a variety of closing schemes to the infinite hierarchy of momentum moments of the exactly solvable Boltzmann equation for systems undergoing Gubser flow, we study the precision with which the resulting hydrodynamic equations reproduce the exact evolution of hydrodynamic moments of the distribution function. We find that anisotropic hydrodynamics, obtained by expanding the distribution function around a dynamically evolving locally anisotropic background whose evolution is matched to exactly reproduce the macroscopic pressure anisotropy caused by the different longitudinal and transverse expansion rates in Gubser ow, provides the most accurate macroscopic description of the microscopic kinetic evolution. This confirms a similar earlier finding for Bjorken ow [Molnar, Niemi and Rischke, Phys. Rev. D 94, 125003 (2016)]. Also, we explain the physics behind this optimal matching procedure and show that one can efficiently correct for a nonoptimized matching choice by adding a residual shear stress to the energy-momentum tensor whose evolution is again determined by the Boltzmann equation. Further insights to guide the optimal choice of a macroscopic anisotropic hydrodynamic framework for strongly-coupled systems that do not admit a microscopic kinetic description are reported.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2016

Computational Fluid Dynamics Modeling of Bubbling in a Viscous Fluid for Validation of Waste Glass Melter Modeling

At the Hanford site, radioactive waste stored in underground tanks is slated for vitrification for final disposal. A comprehensive knowledge of the glass batch melting process will be useful in optimizing the process, which could potentially reduce the cost and duration of this multi-billion dollar cleanup effort. We are developing a high-fidelity heat transfer model of a Joule-heated ceramic lined melter to improve the understanding of the complex, inter-related processes occurring with the melter. The glass conversion rates in the cold cap layer are dependent on promoting efficient heat transfer. In practice, heat transfer is augmented by inserting air bubblers into the molten glass. However, the computational simulations must be validated to provide confidence in the solutions. As part of a larger validation procedure, it is beneficial to split the physics of the melter into smaller systems to validate individually. The substitution of molten glass for a simulant liquid with similar density and viscosity at room temperature provides a way to study mixing through bubbling as an isolated effect without considering the heat transfer dynamics. The simulation results are compared to experimental data obtained by the Vitreous State Laboratory at the Catholic University of America using bubblers placed within a large acrylic tank that is similar in scale to a pilot glass waste melter. Comparisons are made for surface area of the rising air bubbles between experiments and CFD simulations for a variety of air flow rates and bubble injection depths. Also, computed bubble rise velocity is compared to a well-accepted expression for bubble terminal velocity.

bubbling↗
DOE OSTI2016

Computational Fluid Dynamics Modeling of Bubbling in a Viscous Fluid for Validation of Waste Glass Melter Modeling

At the Hanford site, radioactive waste stored in underground tanks is slated for vitrification for final disposal. A comprehensive knowledge of the glass batch melting process will be useful in optimizing the process, which could potentially reduce the cost and duration of this multi-billion dollar cleanup effort. We are developing a high-fidelity heat transfer model of a Joule-heated ceramic lined melter to improve the understanding of the complex, inter-related processes occurring with the melter. The glass conversion rates in the cold cap layer are dependent on promoting efficient heat transfer. In practice, heat transfer is augmented by inserting air bubblers into the molten glass. However, the computational simulations must be validated to provide confidence in the solutions. As part of a larger validation procedure, it is beneficial to split the physics of the melter into smaller systems to validate individually. The substitution of molten glass for a simulant liquid with similar density and viscosity at room temperature provides a way to study mixing through bubbling as an isolated effect without considering the heat transfer dynamics. The simulation results are compared to experimental data obtained by the Vitreous State Laboratory at the Catholic University of America using bubblers placed within a large acrylic tank that is similar in scale to a pilot glass waste melter. Comparisons are made for surface area of the rising air bubbles between experiments and CFD simulations for a variety of air flow rates and bubble injection depths. Also, computed bubble rise velocity is compared to a well-accepted expression for bubble terminal velocity (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Interfacial X-Ray Scattering from Small Surfaces: Adapting Mineral-Fluid Structure Methods for Microcrystalline Materials

Crystal truncation rod (CTR) X-ray diffraction is an invaluable tool for measuring mineral surface and adsorbate structures, and has been applied to several environmentally and geochemically important systems. Traditionally, the method has been restricted to single crystals with lateral dimensions >3 mm. Minerals that meet this size criterion represent a minute fraction of those that are relevant to interfacial geochemistry questions, however. Crystal screening, data collection, and CTR measurement methods have been developed for crystals of <0.3 mm in lateral size using the manganese oxide mineral chalcophanite (ZnMn 3 O 7 •3H 2 O) as a case study. Furthermore, this work demonstrates the feasibility of applying the CTR technique to previously inaccessible surfaces, opening up a large suite of candidate substrates for future study.

58 GEOSCIENCES↗