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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 1,135 records · Page 63

All sources NASA NTRS DOE OSTI

DOE OSTI2017

Model Implementation of Boron Removal Using CaCl{sub 2}-CaO-SiO{sub 2} Slag System for Solar-Grade Silicon

A new CaCl{sub 2}-CaO-SiO{sub 2} slag system was recently proposed to remove boron from metallurgy-grade silicon by oxidized chlorination and evaporation. To further investigate the boron transformation process at a high temperature, a model implementation to present the transfer of boron from molten silicon to the gas phase via slag is introduced. Heat transfer, fluid flow, the chemical reactions at the interface and surface, the mass transfer and diffusion of boron in the molten silicon and slag, and the evaporation of BOCl and CaCl{sub 2} were coupled in this model. After the confirmation of the thermal field, other critical parameters, including the boron partition ratios (L{sub B}) for this slag from 1723 K to 1823 K (1450 °C to 1550 °C), the thicknesses of the velocity boundary layer at the surface and interface, the mass transfer coefficients of the boundary layer at the surface and interface, and partial pressure of BOCl in the gas phase were analyzed to determine the rate-limiting step. To verify this model implementation, boron removal experiments were carried out at various temperatures and with various initial mass ratios of slag to silicon (μ). The evaporation rate of CaCl{sub 2} was also measured by thermogravimetry analysis (TGA).

36 MATERIALS SCIENCE↗

DOE OSTI2022

Tempering kinetics during multilayer laser additive manufacturing of a ferritic steel

Grade 91 steel forms martensite during additive manufacturing and the extent of tempering of martensite significantly affects the mechanical properties of parts. Currently, there is a lack of quantitative understanding of the tempering kinetics for Grade 91 steel, and as a result, the effects of repeated thermal cycles on properties for different processing conditions cannot be determined. Here we evaluate the tempering kinetics by determining the constant terms in the Johnson Mehl Avrami kinetic equation from the tempering data available in the literature and the thermal cycles computed using a rigorously-tested heat and fluid flow model of multi-layer additive manufacturing. The raw tempering data are cleaned using a neural network to enhance accuracy. The lower layers experience repeating cycles of heating and cooling when the upper layers are added. As a result, the hardness is reduced owing to the tempering of martensite. In contrast, martensite formed in the upper layers is not tempered to the same extent and the hardness remains high. Therefore, the hardness of the part increases with the distance from the substrate. Variations in the heat input at different laser powers and scanning speeds significantly affect the extent of tempering. Finally, since the method used here can provide a quantitative understanding of the tempering of martensite and the spatial variation in hardness, it can be used to tailor the microstructure and hardness of heat treatable printed metallic parts.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Modeling of Keyhole-Induced Pore Formation in Laser-Arc Hybrid Welding of Aluminum Alloy with a Horizontal Fillet Joint

A three-dimensional transient model is proposed to investigate the weld pool dynamic behavior in laser + metal inert gas (MIG) hybrid fillet welding of aluminum alloy in the horizontal position, which allows for the joint configuration and coupling of the keyhole, droplet and weld pool as well as the heat and mass exchange between gas and liquid phases and is able to simulate the temperature distribution, fluid flow and formation process of a keyhole-induced pore in hybrid welding with a horizontal fillet joint. The weld porosity is also measured using x-ray nondestructive testing technology. Keyhole behavior and the formation mechanism of keyhole-induced porosity were analyzed. The calculated results are in generally good agreement with the experimental ones. A clockwise vortex always exists at the middle part of the weld pool. The formation and growth of the molten metal bulge on the keyhole wall are responsible for the occurrence of a gas bubble, which has a variation in size and shape and can be split during welding. The keyhole collapses easily at its middle or upper part in horizontal fillet welding, and the capture of the bubble by the upper molten pool boundary enhances the possibility of porosity formation to some degree. The keyhole-induced pore is mainly formed at the regions near the keyhole bottom and the upper fusion line of the weld pool.

36 MATERIALS SCIENCE↗

NASA NTRS1965

Effects of momentum buffer region on coaxial flow of dissimilar fluids

COAXIAL FLOW↗

DOE OSTI2018

Stress and Friction Distribution around Slab Corner in Continuous Casting Mold with Different Corner Structures

The non-uniform friction and thermal stress in the mold are important as causes of the transverse cracks around strand corner. To analyze the stress distribution features around strand corner, a three-dimensional thermo-elastoplastic finite-element mold model with different corner structures (right-angle, big-chamfer, multi-chamfer, and fillet) was established. The temperature field in the mold was indirectly coupled through a three-dimensional fluid flow and heat transfer model. In addition, the non-uniform mold friction stress loaded on the strand surface was calculated through a friction model. The results show that the stress distribution on the shell is similar to the temperature distribution. The stress concentration appears in the strand corner and the lower part of wide face. The friction stress enhances the corner stress around the edge of the air-gap. For chamfered molds, the stress around the corner between the wide face and chamfer face is larger than that between the narrow face and chamfer face. Around the corner region, both the stress peak and the area of the large stress zone of the right-angle strand are the largest, while those of big-chamfered, multi-chamfered, and fillet strands decrease in that order. The stress peak position of the chamfered strands is closer to the mold exit than that of the right-angle strand. Compared with the use of the right-angle mold, the application of chamfered molds is able to reduce the stress concentration around the strand corner.

36 MATERIALS SCIENCE↗

DOE OSTI2021

System and method for controlling metal oxide gel particle size

Metal oxide gel particles, may be prepared with a desired particle size, by preparing a low-temperature aqueous metal nitrate solution containing hexamethylene tetramine as a feed solution; and causing the feed solution to flow through a first tube and exit the first tube as a first stream at a first flow rate, so as to contact a high-temperature nonaqueous drive fluid. The drive fluid flows through a second tube at a second flow rate. Shear between the first stream and the drive fluid breaks the first stream into particles of the metal nitrate solution, and decomposition of hexamethylene tetramine converts metal nitrate solution particles into metal oxide gel particles. A metal oxide gel particle size is measured optically, using a sensor device directed at a flow of metal oxide gel particles within the stream of drive fluid. The sensor device measures transmission of light absorbed by either the metal oxide gel particles or the drive fluid, so that transmission of light through the drive fluid changes for a period of time as a metal oxide gel particle passes the optical sensor. If a measured particle size is not about equal to a desired particle size, the particle size may be corrected by adjusting a ratio of the first flow rate to a total flow rate, where the total flow rate is the sum of the first and second flow rates.

Linneen, Nicholas N.↗

DOE OSTI2023

System and method for controlling metal oxide gel particle size

Linneen, Nicholas↗

DOE OSTI2023

Enhancement of operational Flexibility of Power Plants Using IN740

Headers are crucial components within diverse industries, especially in the energy sector, as they enable the efficient transfer of fluids. The selection of materials for headers is determined by their specific applications; for example, Grade 91 and Grade 92 steels are commonly utilized. In our research, we recommend the adoption of INCONEL alloy 740 due to its exceptional robustness and heat-resistant characteristics. One critical parameter in header systems is the heat transfer coefficient, which directly influences the efficiency of heat exchange processes and can thereby impact the structural integrity of the headers. This coefficient is closely linked with factors such as the Nusselt number, which is influenced by fluid flow characteristics and thermal properties. The flow direction within headers, whether unidirectional or multidirectional—significantly affects the overall dynamics of heat transfer. This research focuses on exploring the behavior of headers, a specific pipeline system component, using ANSYS simulation software. The study aims to predict heat transfer and mechanical behavior within headers under various conditions through steady-state and transient simulations (parts 1 and 2 of the report). Key parameters such as heat transfer coefficient, velocity, and temperature are examined with the goal of optimizing header design. Part 3 of the report addresses the critical yet underexplored relationship between pressure drop and heat transfer coefficients in the transient flow regime within headers, specifically focusing on smooth horizontal circular tubes. Limited experimental work has been conducted in this area, prompting the need for comprehensive analysis. By leveraging machine learning techniques, this research aims to establish a correlation between pressure drop and heat transfer across various flow conditions, including laminar, transient, quasi-turbulent, and turbulent regimes. The data utilized for this analysis were meticulously gathered from existing literature, capturing simultaneous measurements of pressure drops and heat transfer. Part 4: In the context of power plants, header pipes are essential components that significantly influence system performance by facilitating the collection and distribution of steam. This report highlights the critical role of header pipes in enhancing reliability, efficiency, and overall power plant performance. A key aspect of this investigation is shape optimization, which aims to maximize performance while minimizing material usage. By focusing on shape optimization, this research contributes to improved efficiency and a reduced environmental footprint for power plant installations. The methodology developed in this study emphasizes optimizing header shapes to decrease reliance on expensive alloy materials and lower maintenance costs. Furthermore, a case study was conducted using a header from an operational power plant to validate the proposed optimization techniques. Finally, part 5 addresses the challenges associated with flexible operations in boiler systems, the study outlines several strategies for enhancing the durability and reliability of steam headers. Key approaches include material selection, which involves utilizing advanced materials with superior high-temperature properties and enhanced fatigue resistance to extend the lifespan of steam headers. Design modifications are also recommended, focusing on implementing changes that mitigate thermal stress and cyclic loading to reduce the likelihood of failures under varying operating conditions. Additionally, the study emphasizes the importance of regular inspection and monitoring by establishing rigorous protocols to detect early signs of damage, allowing for timely maintenance and minimizing the risks of catastrophic failures. Furthermore, operational guidelines are developed to minimize the frequency and severity of thermal transients, ensuring stable and efficient operations. Collectively, these strategies provide a robust framework for overcoming the unique challenges posed by flexible operation in boiler systems, ultimately contributing to improved reliability and performance in power plant operations. Through this comprehensive approach, the study not only enhances the understanding of pressure drop and heat transfer relationships but also promotes advancements in design and operation that will benefit the entire power generation industry.

01 COAL, LIGNITE, AND PEAT↗

NASA NTRS1985

Three dimensional flow phenomena in fluid machinery; Proceedings of the Winter Annual Meeting, Miami Beach, FL, November 17-22, 1985

For papers presented in this volume provide an overview of the latest developments in experimental measurements and analytical and numerical predictions of three-dimensional flows in fluid machinery. Topics discussed include three-dimensional cascade testing of turbine nozzles at high exit Mach number; the use of a secondary flow computation in the compressor design process; an experimental investigation of static propeller flow field; and calculation of three-dimensional boundary layers on rotating turbine blades. Papers are also presented on a three-dimensional solution method for turbomachinery analysis; analysis of rotational inviscid flows in curved passages; and a mathematical model for the analysis of fluid flow in a scroll.

Hamed, A.↗

DOE OSTI2022

Blending and cavern formation within non-Newtonian fluids in stirred tanks: Application to nuclear waste fluid processing

A numerical approach for predicting the time-accurate fluid flow and mixing properties of non-Newtonian fluids is presented. This approach, which is based on the lattice Boltzmann method, is used to characterize the blending in shear-thinning fluids, as well as cavern formation in yield-stress fluids. Predictions compare favorably to measured data and expectations from first-principles theory. Importantly, across the range of fluids and systems here, the simulations require no reparameterization or retuning between scenarios. This generality is exploited to model a nuclear waste processing unit operation.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2021

Gouge formation and dilation impacts to flow during fracture shearing

We report flow in fractures is of critical importance to fluid flow in low-permeability shales, particularly when they restrict vertical migration from reservoirs. The Mt. Simon Sandstone is a target for geologic CO 2 sequestration and the overlying Eau Claire Formation is the sealing formation capping this reservoir. The lower Eau Claire, a primary barrier to upward migration of CO 2 from the Mt. Simon, is lithologically heterogenous with a mixture of sandstone and shale. We use a series of flow-through experiments on fractured samples from the Eau Claire to document the morphological changes taking place in the fracture and surrounding rock as it is sheared in a stepwise fashion. The samples were imaged using computed tomography after each shearing episode and flow resistance was calculated based on the pressure differential across each core. We found that gouge accumulations in the fracture plane led to specific instances of self-sealing behavior despite the fact that most samples increased in average fracture aperture and transmissivity. Gouge limited the increase or, in some cases, decreased flow through these samples. Fractures adjacent to shale-rich zones and concordant with bedding were more likely to show evidence of self-sealing, while increased sandstone content and fracture orientation perpendicular to bedding planes was more likely to result in fracture dilation and fracture permeability increases. Reactivation and shearing of vertical fractures in lithologically heterogenous caprocks is more likely to pose risks to long term CO 2 storage scenarios.

58 GEOSCIENCES↗

DOE OSTI2025

Joint state-parameter estimation for the reduced fracture model via the united filter

Here, in this paper, we introduce an effective United Filter method for jointly estimating the solution state and physical parameters in flow and transport problems within fractured porous media. Fluid flow and transport in fractured porous media are critical in subsurface hydrology, geophysics, and reservoir geomechanics. Reduced fracture models, which represent fractures as lower-dimensional interfaces, enable efficient multi-scale simulations. However, reduced fracture models also face accuracy challenges due to modeling errors and uncertainties in physical parameters such as permeability and fracture geometry. To address these challenges, we propose a United Filter method, which integrates the Ensemble Score Filter (EnSF) for state estimation with the Direct Filter for parameter estimation. EnSF, based on a score-based diffusion model framework, produces ensemble representations of the state distribution without deep learning. Meanwhile, the Direct Filter, a recursive Bayesian inference method, estimates parameters directly from state observations. The United Filter combines these methods iteratively: EnSF estimates are used to refine parameter values, which are then fed back to improve state estimation. Numerical experiments demonstrate that the United Filter method surpasses the state-of-the-art Augmented Ensemble Kalman Filter, delivering more accurate state and parameter estimation for reduced fracture models. This framework also provides a robust and efficient solution for PDE-constrained inverse problems with uncertainties and sparse observations.

Bayesian inference↗

DOE OSTI2021

Analysis of Geologic CO 2 Migration Pathways in Farnsworth Field, NW Anadarko Basin

This study reports on analyses of natural, geologic CO 2 migration paths in Farnsworth Oil Field, northern Texas, where CO 2 was injected into the Pennsylvanian Morrow B reservoir as part of enhanced oil recovery and carbon sequestration efforts. We interpret 2D and 3D seismic reflection datasets of the study site, which is located on the western flank of the Anadarko basin, and compare our seismic interpretations with results from a tracer study. Petroleum system models are developed to understand the petroleum system and petroleum- and CO 2 -migration pathways. We find no evidence of seismically resolvable faults in Farnsworth Field, but interpret a karst structure, erosional structures, and incised valleys. These interpretations are compared with results of a Morrow B well-to-well tracer study that suggests that inter-well flow is up-dip or lateral. Southeastward fluid flow is inhibited by dip direction, thinning, and draping of the Morrow B reservoir over a deeper, eroded formation. Petroleum system models predict a deep basin-ward increase in temperature and maturation of the source rocks. In the northwestern Anadarko Basin, petroleum migration was generally up-dip with local exceptions; the Morrow B sandstone was likely charged by formations both below and overlying the reservoir rock. Based on this analysis, we conclude that CO 2 escape in Farnsworth Field via geologic pathways such as tectonic faults is unlikely. Abandoned or aged wellbores remain a risk for CO 2 escape from the reservoir formation and deserve further monitoring and research.

58 GEOSCIENCES↗

NASA NTRS1965

A color Schlieren system

Color schlieren photographic system for analysis of complex compressible fluid flows

FLUID MECHANICS↗

NASA NTRS1971

Low-temperature Brayton radiator performance in a variable-sink-temperature environment

An analysis of the performance of a low-temperature Brayton space radiator is presented. The cylindrical radiator with circumferential tubes was subjected to an equivalent sink temperature environment that varied along the fluid flow path. The radiator performance, as measured by fluid outlet temperature, was found to be dependent on the orbital position and the location of the radiator inlet relative to the sink temperature environment. An approximate dynamic analysis of sun-shade variations in performance is included.

Bien, D. B.↗

NASA NTRS1981

Convection in fluids at reduced gravity

Natural convection is not always harmful and, therefore, to be avoided. In some situations it may be desirable to have fluid flows in space processes, e.g., to stir the fluid phase for mixing and cooling or to help maintain concentration gradients. In may event, it is important to know the extent and nature of convection in space and the factors on which it depends, in order either to minimize the effects to convection, or to utilize the convection to advantage. The information needed to assess both conventional and unstable convection includes: (1) the magnitude and direction of accelerations; (2) geometric configuration; (3) imposed boundary conditions; and (4) material properties.

Ostrach, S.↗

NASA NTRS1986

Advanced thermal energy management: A thermal test bed and heat pipe simulation

Work initiated on a common-module thermal test simulation was continued, and a second project on heat pipe simulation was begun. The test bed, constructed from surplus Skylab equipment, was modeled and solved for various thermal load and flow conditions. Low thermal load caused the radiator fluid, Coolanol 25, to thicken due to its temperature avoided by using a regenerator-heat-exchanger. Other possible solutions modeled include a radiator heater and shunting heat from the central thermal bus to the radiator. Also, module air temperature can become excessive with high avionics load. A second preoject concerning advanced heat pipe concepts was initiated. A program was written which calculates fluid physical properties, liquid and vapor pressure in the evaporator and condenser, fluid flow rates, and thermal flux. The program is directed to evaluating newer heat pipe wicks and geometries, especially water in an artery surrounded by six vapor channels. Effects of temperature, groove and slot dimensions, and wick properties are reported.

Barile, Ronald G.↗

NASA NTRS1987

Reconstruction techniques of holograms from Spacelab 3

Fluid transport effects in a ground-based laboratory are fairly well known. Bouyancy driven transport occurs when there is a local density change in the fluid. In a low-g environment these density changes become less important, and other transport mechanisms dominate. To better understand fluid flows in a low-g environment, a fluid experiment system (FES) was designed to fly aboard the Shuttle orbiter in Spacelab. The FES is a holographic system designed for acquisition of the maximum amount of data from an experiment. The FES flew for the first time in May 1985 on Spacelab 3 for investigation of triglycine sulfate (TGS) crystal growth in low-g. This paper describes the FES optical system. The reconstruction techniques of the holograms are examined in detail, and the multiuser and reflight capabilities are discussed. Proposed future experiments are mentioned.

Witherow, William K.↗