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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Foamed Cement Generation Methods: Insights from Macro-Porosity and Void Distribution

The American Petroleum Institute (API) Recommended Practice 10B-4 is the industry standard for measuring foamed cement stability, however, it does not incorporate the effects of elevated pressure or placement. Using high resolution computed tomography (CT) scanning, this study examines how cement slurry flow through pipes impacts void distribution in cured foamed cement. Analysis of the void size and distribution allows a comparison of lab and field generation; simulated velocity profiles indicate cement flow through constrictions likely 4 influences structural variations. Notably, field generated samples show more nitrogen bubbles at the injection port. Moreover, a review of the average bubble diameter concludes lab samples have average bubble sizes that increase with their quality, while field samples have similar average bubble diameters suggesting variation among generation methods.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Measurement and Analysis of Porosity in Al-10Si-1Mg Components Additively Manufactured by Selective Laser Melting

Aluminum alloys are candidate materials for weight critical applications because of their excellent strength and stiffness to weight ratio. However, defects such as voids decrease the strength and fatigue life of these alloys, which can limit the application of Selective Laser Melting. In this study, the average volume fraction, average size, and size distribution of pores in Al10-Si-1Mg samples built using Selective Laser Melting have been characterized. Synchrotron high energy X-rays were used to perform computed tomography on volumes of order one cubic millimeter with a resolution of approximately 1.5 μm. Substantial variations in the pore size distributions were found as a function of process conditions. Even under conditions that ensured that all locations were melted at least once, a significant number density was found of pores above 5 μm in diameter.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Raptor: A Python Library for Porosity Predictions in Additive Manufacturing

Raptor is an efficient Python library for simulating stochastic lack-of-fusion (sLoF) defects in additive manufacturing (AM) processes. These defects arise from stochastic variations in the melt pool boundary leading to undermelting from insufficient overlap between adjacent melt pools or successive layers (Grasso & Colosimo, 2017; Khairallah et al., 2016). Performance variability of AM parts is a pressing challenge in qualification and certification of AM parts; this is in part due to the poorly understood formation rate and statistics of sLoF defects. Raptor is designed to capture the explicit morphologies of sLoF defects and their statistics to accelerate qualification and certification efforts of AM parts in critical applications.

Subraveti, Vamsi [Vanderbilt University]↗
DOE OSTI2014

Low-Density and High Porosity Hydrogen Storage Materials Built from Ultra-Light Elements. Final Scientific/Technical Report

A number of significant advances have been achieved, opening up new opportunities for the synthetic development of novel porous materials and their energy-related applications including gas storage and separation and catalysis. These include lithium-based metal-organic frameworks, magnesium-based metal-organic frameworks, and high gas uptake in porous frameworks with high density of open donor sites.

08 HYDROGEN↗
DOE OSTI2014

Maximization of permanent trapping of CO{sub 2} and co-contaminants in the highest-porosity formations of the Rock Springs Uplift (Southwest Wyoming): experimentation and multi-scale modeling

Under this project, a multidisciplinary team of researchers at the University of Wyoming combined state-of-the-art experimental studies, numerical pore- and reservoir-scale modeling, and high performance computing to investigate trapping mechanisms relevant to geologic storage of mixed scCO{sub 2} in deep saline aquifers. The research included investigations in three fundamental areas: (i) the experimental determination of two-phase flow relative permeability functions, relative permeability hysteresis, and residual trapping under reservoir conditions for mixed scCO{sub 2}-­brine systems; (ii) improved understanding of permanent trapping mechanisms; (iii) scientifically correct, fine grid numerical simulations of CO{sub 2} storage in deep saline aquifers taking into account the underlying rock heterogeneity. The specific activities included: (1) Measurement of reservoir-­conditions drainage and imbibition relative permeabilities, irreducible brine and residual mixed scCO{sub 2} saturations, and relative permeability scanning curves (hysteresis) in rock samples from RSU; (2) Characterization of wettability through measurements of contact angles and interfacial tensions under reservoir conditions; (3) Development of physically-­based dynamic core-­scale pore network model; (4) Development of new, improved high-­performance modules for the UW-­team simulator to provide new capabilities to the existing model to include hysteresis in the relative permeability functions, geomechanical deformation and an equilibrium calculation (Both pore-­ and core-­scale models were rigorously validated against well-­characterized core-­ flooding experiments); and (5) An analysis of long term permanent trapping of mixed scCO{sub 2} through high-­resolution numerical experiments and analytical solutions. The analysis takes into account formation heterogeneity, capillary trapping, and relative permeability hysteresis.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

DE-SC0004118 (Wong & Lindquist). Final Report: Changes of Porosity, Permeability and Mechanical Strength Induced by Carbon Dioxide Sequestration.

In the context of CO{sub 2} sequestration, the overall objective of this project is to conduct a systematic investigation of how the flow of the acidic, CO{sub 2} saturated, single phase component of the injected/sequestered fluid changes the microstructure, permeability and strength of sedimentary rocks, specifically limestone and sandstone samples. Hydromechanical experiments, microstructural observations and theoretical modeling on multiple scales were conducted.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Computational and Experimental Studies of Microstructure-Scale Porosity in Metallic Fuels for Improved Gas Swelling Behavior

This proposal will investigate the stability of bimodal pore size distributions in metallic uranium and uranium-zirconium alloys during sintering and re-sintering annealing treatments. The project will utilize both computational and experimental approaches. The computational approach includes both Molecular Dynamics simulations to determine the self-diffusion coefficients in pure U and U-Zr alloys in single crystals, grain boundaries, and free surfaces, as well as calculations of grain boundary and free surface interfacial energies. Phase-field simulations using MOOSE will be conducted to study pore and grain structure evolution in microstructures with bimodal pore size distributions. Experiments will also be performed to validate the simulations, and measure the time-dependent densification of bimodal porous compacts.

36 MATERIALS SCIENCE↗