SEARCH · Search NASA

Results for “Mass loading”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 685 records · Page 38

All sources NASA NTRS DOE OSTI

NASA NTRSDate not supplied

Solvent-Free Preparation of High Energy, Binder-Free Electrodes Enabled by Dry Compressible Holey Graphene

Graphene is an atomically thick sheet consisting of a graphitic carbon network with excellent mechanical strength, electrical and thermal conductivity, and chemical stability. Holey graphene, a structural derivative of graphene, has an array of through-the-thickness holes across the lateral surface of the nanosheet. The presence of these holes has minimal detrimental effect on the graphene properties and leads to enhanced performance in applications such as electronics, sensors, and energy storage. For example, these holes allow more facile cross-plane ion and gas transport than intact graphene, making holey graphene an ideal electrode material for electrochemical energy storage. This presentation will focus on the ability of holey graphene to be compression molded into robust articles or architectures under solvent-free conditions without the need for potentially parasitic binders. The unique dry compressibility of holey graphene has enabled facile fabrication of high mass loading electrodes with both high density and high porosity, which have found use in supercapacitors and various high-energy battery systems such as lithium-oxygen, lithium-sulfur, and lithium-selenium batteries.

Yi Lin↗

NASA NTRSDate not supplied

Coupling a Particle Trajectory Capability to the US3D CFD Flow Solver

The purpose of the current research effort is to incorporate particle trajectory equations into the US3D CFD flow solver. The integrated code will allow higher-fidelity modeling of particle-fluid interactions and allow for the simulation of physical effects such as surface heating augmentation due to particle impacts. The key elements underpinning the current work are a robust tracking algorithm that can identify the encompassing mesh elements for individual particles and a point to point MPI frame-work. These developments combined with accurate property models and high-order time-stepping deliver realistic simulations on larger computational grids for a wide range of particle mass loadings. The coupled US3D-particle code will be applied to the Schiarparelli capsule and Earth-based experimental test cases.

A Sahai↗

NASA NTRS2020

Nonstationary Quasiperpendicular Shock and Ion Reflection at Mars

Collisionless shocks in space plasma are regions of heating and acceleration of charged particles and dissipation of kinetic energy. These accelerated particles are the source of electromagnetic emissions from supernova remnants and other astrophysical structures.At high Mach numbers, shocks can be inherently nonstationary and exhibit modulated energy transfer and recurring plasma compression areas in the form of reformation. We use data from the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft to study reformation of the Martian bow shock which has a relatively high curvature compared to that at Earth and the upstream solar wind is often mass loaded with a population of pickup ions. We show evidence of ion reflection effects in reformation of a supercritical quasi-perpendicular shock.

Hadi Madanian↗

NASA NTRS1999

A Priori Subgrid Analysis of Temporal Mixing Layers with Evaporating Droplets

Subgrid analysis of a transitional temporal mixing layer with evaporating droplets has been performed using three sets of results from a Direct Numerical Simulation (DNS) database, with Reynolds numbers (based on initial vorticity thickness) as large as 600 and with droplet mass loadings as large as 0.5.

subgrid↗

NASA NTRS2020

Variability of the Solar Wind Flow Asymmetry in the Martian Magnetosheath Observed by MAVEN

We perform the first statistical analysis of effects that different external conditions20have on a solar wind (SW) flow asymmetry observed in the Martian magnetosheath due to mass loading, making use of∼5 years of Mars Atmosphere and Volatile EvolutioN22(MAVEN) observations. We find the difference between the mean magnetosheath SW velocity component along the SW convective electric field direction in regions in the positive and negative hemispheres displays a strong linear correlation with the ratio between the upstream Interplanetary Magnetic Field (IMF) cross-flow component (By) and the SW proton density (nsw). The asymmetry is maximized (∼25 - 35 kms−1) for low nsw(∼1 cm−3) and large IMF By(∼2 nT). These results suggest the SW flow asymmetry variability is due to a force arising from the differential streaming between SW protons and oxygen ions, with boundary conditions partly defined by the pristine SW properties.

N Romanelli↗

NASA NTRS2020

Concerning the Interaction of A Transmitted Interplanetary Impulse With A Plasmaspheric Drainage Plume: First Results From 3-D Hybrid Kinetic Modeling

We present a new hybrid kinetic model to simulate the response of plasmaspheric drainage plumes to impulsive interplanetary pressure pulses. Since particle distributions attending the interplanetary pulses and in the drainage plume are non-Maxwellian, wave-particle interactions play a crucial role in energy transport within and outside the plumes. Finite gyroradius effects become important in mass loading of the transmitted impulse with the drainage plume ions. A forward-reverse shock structure develops from the initial step-like transmitted shock. First results show that the impulse causes strong deformations in the global structure of the plume. The anisotropic ion velocity distribution functions at the impulse front and inside the plume help us determine energy transport via wave-particle interactions throughout the Earth’s inner magnetosphere.

A S Lipatov↗

NASA NTRSDate not supplied

Impacts of Cold Ionospheric Ions in Magnetic Reconnection at the Earth’s Magnetopause and Magnetotail

The Earth’s magnetosphere is filled by particles from two sources: the solar wind and the ionosphere. Ionospheric ions are initially cold and contain He+ and O+, in addition to to H+. Depending on their initial magnetic latitude and local time, and the state of the magnetosphere, they may contribute to the plasmasphere, the plasma sheet, the ring current, the warm plasma cloak etc. Depending on which path they follow in the magnetosphere, some of these ionospheric ions remain cold when they reach the two key reconnection regions: the Earth’s magnetopause and the plasma sheet in the tail. In this presentation, we will first review previous statistical works that quantify the number of cold/ionospheric ions near these two regions. Several works have attempted to quantify these populations, but they are inherently difficult to characterize due to their low energy, often below the spacecraft potential. We will also discuss the impacts they have on the magnetic reconnection process. Ionospheric ions mass-load the regions where reconnection takes place and change the characteristic Alfven speed, resulting in a smaller reconnection electric field. They also take a portion of the energy that is imparted to particles, affecting the energy budget of magnetic reconnection. Finally, they introduce new length and time scales, associated to their gyroradius and gyroperiod. We will discuss what are the implications of these impacts for the evolution of the magnetosphere – solar wind interactions.

Sergio Toledo Redondo↗

NASA NTRSDate not supplied

Modeling Evolvable Water Recovery Systems for Short and Long-Duration Missions in Partial Gravity

Water recovery technologies on the International Space Station (ISS) are designed and optimized for microgravity environments, thus creating a need for innovative systems optimized for mission operations in the presence of gravity. Alternative water recovery technologies under research by the Life Support Systems division were compiled into a series of Partial Gravity Water Recovery System (PGWRS) architectures. Individual unit processes were modeled via fundamental physical-chemical process equations to simulate their method of treatment, including chemical or biological oxidation, flash evaporation, filtration, or a combination of adsorption and ion exchange processes. Dimension and sizing data were then utilized to scale each architecture. Modeling was completed on an assortment of architectures assuming three scenarios in which treatment methods could take advantage of partial gravity: a short-duration mission with a temporary surface habitat, a longer duration mission with a more permanent habitat, and a long duration mission without resupply. Total system mass was estimated to quantitatively compare architectures within scenarios, but qualitative observations were also made regarding system robustness, flexibility, and capacity to meet more stringent demands. Technologies that traded most favorably between the scenarios were those that included a pre-oxidation stage to minimize mass loading to downstream absorption and ion exchange beds, exploited gravity in liquid-vapor separation processes, and reconstituted wastewater components into recyclable material streams.

Avery Carlson↗

NASA NTRSDate not supplied

Modeling Evolvable Water Recovery Systems for Short and Long-Duration Missions in Partial Gravity

Avery L. Carlson↗

NASA NTRS2024

Modeling Evolvable Water Recovery Systems for Short and Long-Duration Missions in Partial Gravity

Water recovery technologies on the International Space Station (ISS) are designed and optimized for microgravity environments, thus creating a need for innovative systems optimized for mission operations in the presence of gravity. Alternative water recovery technologies under research by the Life Support Systems division were compiled into a series of Partial Gravity Water Recovery System (PGWRS) architectures. Individual unit processes were modeled via fundamental physical-chemical process equations to simulate their method of treatment, including chemical or biological oxidation, flash evaporation, filtration, or adsorption and ion exchange. Dimension and sizing data were then utilized to scale each architecture. Modeling was completed on an assortment of architectures assuming three scenarios in which treatment methods could take advantage of partial gravity: a short-duration mission with a temporary surface habitat, a longer duration mission with a more permanent habitat, and a long duration mission with minimal resupply. Total system mass was estimated to quantitatively compare architectures within scenarios, but qualitative observations were also made regarding system robustness, flexibility, and capacity to meet more stringent demands. Technologies that traded most favorably between the scenarios were those that included a pre-oxidation stage to minimize mass loading to downstream absorption and ion exchange beds, exploited gravity in liquid-vapor separation processes, and reconstituted wastewater components into recyclable material streams.

Avery L. Carlson↗

NASA NTRS2024

Localized Magnetopause Erosion at Geosynchronous Orbit by Reconnection

This study presents observations of magnetopause reconnection and erosion at geosynchronous orbit, utilizing in situ satellite measurements and remote sensing ground‐based instruments. During the main phase of a geomagnetic storm, Geostationary Operational Environmental Satellites (GOES) 15 was on the dawnside of the dayside magnetopause (10.6 MLT) and observed significant magnetopause erosion, while GOES 13, observing duskside (14.6 MLT), remained within the magnetosphere. Combined observations from the THEMIS satellites and Super Dual Auroral Radar Network radars verified that magnetopause erosion was primarily caused by reconnection. While various factors may contribute to asymmetric erosion, the observations suggest that the weak reconnection rate on the duskside can play a role in the formation of asymmetric magnetopause shape. This discrepancy in reconnection rate is associated with the presence of cold dense plasma on the duskside of the magnetosphere, which limits the reconnection rate by mass loading, resulting in more efficient magnetopause erosion on the dawnside.

Hyangpyo Kim↗

NASA NTRSDate not supplied

Modeling Evolvable Water Recovery Systems for Short and Long-Duration Missions in Partial Gravity

Water recovery technologies on the International Space Station (ISS) are designed and optimized for microgravity environments, thus creating a need for innovative systems optimized for mission operations in the presence of gravity. Alternative water recovery technologies under research by the Life Support Systems division were compiled into a series of Partial Gravity Water Recovery System (PGWRS) architectures. Individual unit processes were modeled via fundamental physical-chemical process equations to simulate their method of treatment, including chemical or biological oxidation, flash evaporation, filtration, or adsorption and ion exchange. Dimension and sizing data were then utilized to scale each architecture. Modeling was completed on an assortment of architectures assuming three scenarios in which treatment methods could take advantage of partial gravity: a short-duration mission with a temporary surface habitat, a longer duration mission with a more permanent habitat, and a long duration mission with minimal resupply. Total system mass was estimated to quantitatively compare architectures within scenarios, but qualitative observations were also made regarding system robustness, flexibility, and capacity to meet more stringent demands. Technologies that traded most favorably between the scenarios were those that included a pre-oxidation stage to minimize mass loading to downstream absorption and ion exchange beds, exploited gravity in liquid-vapor separation processes, and reconstituted wastewater components into recyclable material streams.

Avery Carlson↗

NASA NTRS2024

Global Influence of Organic Aerosol Volatility on Aerosol Microphysical Processes: Composition and Number

We present MATRIX-VBS, a new aerosol scheme that simulates organic partitioning in an aerosol microphysics model, as part of the NASA GISS ModelE Earth System Model. MATRIX-VBS builds on its predecessor aerosol microphysics model MATRIX (Bauer et al., 2008, https://doi.org/10.5194/acp-8-6003-2008) and was developed in the box model framework (Gao et al., 2017, https://doi.org/10.5194/gmd-10-751-2017). The scheme features the inclusion of organic partitioning between the gas and particle phases and the photochemical aging process using the volatility-basis set (Donahue et al., 2006, https://doi.org/10.1021/es052297c). To assess the performance of the new model, we compared its mass concentration, number concentration, and activated number concentration to the original scheme MATRIX, and evaluated its mass concentrations in four seasons against data from the NASA Atmospheric Tomography Mission (ATom) aircraft campaign. Results from MATRIX-VBS show that organics are transported further away from their source, and their mass concentration increases aloft and decreases at the surface compared to those in MATRIX. The mass concentration of organics at the surface agrees well with measurements, and there are discrepancies for vertical profiles aloft. In the new scheme, the global mass load of organic aerosols increased by 50%, there is also an increased number of particles at the surface and fewer activated ones in most regions. The new scheme presents advanced and more comprehensive capability in simulating aerosol processes.

aerosol modeling↗

NASA NTRSDate not supplied

Improvements in VLBI Data Analysis for Advanced in Geodesy

I will provide an overview of advances in VLBI data analysis implemented at NASA GSFC. That include the use of B-splines for modeling non-linear station position evolution, the use of all non-tidal mass loadings in data reduction, the use of slant a priori path delays from the output of numerical weather models, the use of B-splines for evaluation of the Earth orientation parameters as a continuous function, the use of elevation-dependent weighting, processing both 24 hr and 1 hr experiments in a single least square solutions and other innovations. I will show how this changes in data analysis affect space geodesy results, such as estimation of station positions, Earth orientation parameters, and source coordinates.

Leonid Petrov↗

DOE OSTI2014

Direct Numerical Simulation of Particle Behaviour in a Gas-Solid Three Dimensional Plane Jet

In this paper, direct numerical simulations (DNS) of a three-dimensional (3D), non-reacting, temporally evolving planar jet laden with mono-dispersed solid particles in the two-way coupling (TWC) regime are performed. Three different particles Stokes numbers (St = 0.1, 1, 10) have been considered. This has been achieved by varying the particle diameter while keeping the particle mass loading (fm = 1) and the jet Reynolds number (Rejet = 2000) unchanged. The objective is to study the effect of the particle Stokes number TWC regime on the temporal development of the planar jet. Two-way coupled momentum and heat transfer has been studied by investigating mean relative velocity and temperature. Results indicate that the relative parameters are more pronounced on the edges of the jet and decrease in time in general. At the center of the jet however, the mean value first increases and then decreases again. Additionally, lighter particles spread farther than heavier particles from the center of the jet. Furthermore, the heavier particles delay the development of the jet due to TWC effects.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2017

Thick electrodes including nanoparticles having electroactive materials and methods of making same

Electrodes having nanostructure and/or utilizing nanoparticles of active materials and having high mass loadings of the active materials can be made to be physically robust and free of cracks and pinholes. The electrodes include nanoparticles having electroactive material, which nanoparticles are aggregated with carbon into larger secondary particles. The secondary particles can be bound with a binder to form the electrode.

36 MATERIALS SCIENCE↗

DOE OSTI2017

Metallic Nanocomposites as Next-Generation Thermal Interface Materials: Preprint

Thermal interface materials (TIMs) are an integral and important part of thermal management in electronic devices. The electronic devices are becoming more compact and powerful. This increase in power processed or passing through the devices leads to higher heat fluxes and makes it a challenge to maintain temperatures at the optimal level during operation. Herein, we report a free standing nanocomposite TIM in which boron nitride nanosheets (BNNS) are uniformly dispersed in copper matrices via an organic linker, thiosemicarbazide. Integration of these metal-organic-inorganic nanocomposites was made possible by a novel electrodeposition technique where the functionalized BNNS (f-BNNS) experience the Brownian motion and reach the cathode through diffusion, while the nucleation and growth of the copper on the cathode occurs via the electrochemical reduction. Once the f-BNNS bearing carbonothioyl/thiol groups on the terminal edges come into the contact with copper crystals, the chemisorption reaction takes place. We performed thermal, mechanical, and structural characterization of these nanocomposites using scanning electron microcopy (SEM), diffusive laser flash (DLF) analysis, phase-sensitive transient thermoreflectence (PSTTR), and nanoindentation. The nanocomposites exhibited a thermal conductivity ranging from 211 W/mK to 277 W/mK at a filler mass loading of 0-12 wt.percent. The nanocomposites also have about 4 times lower hardness as compared to copper, with values ranging from 0.27 GPa to 0.41 GPa. The structural characterization studies showed that most of the BNNS are localized at grain boundaries - which enable efficient thermal transport while making the material soft. PSTTR measurements revealed that the synergistic combinations of these properties yielded contact resistances on the order of 0.10 to 0.13 mm2K/W, and the total thermal resistance of 0.38 to 0.56 mm2K/W at bondline thicknesses of 30-50 um. The coefficient of thermal expansion (CTE) of the nanocomposite is 11 ppm/K, which lies between the CTEs of aluminum (22 ppm/K) and silicon (3 ppm/K), which are common heat sink and heat source materials, respectively. The nanocomposite can also be deposited directly on to heat sink which will simplify the packaging processes by removing one possible element to assemble. These unique properties and ease of assembly makes the nanocomposite a promising next-generation TIM.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2017

Sub-Grid Model Improving Shrinking Core Simulations of Redox-Sensitive Technetium Release From Slag Cement Waste Forms - 17295

Numerical simulation of Tc transport in reducing cementitious materials undergoing oxidation is challenging because the effective solid-solute partition coefficient (K{sub d}) varies greatly between the reduced and oxidized states, assuming the Tc mass loading far exceeds that required to reach solubility in the aqueous phase, as is typical in waste disposal. In a conventional finite-volume formulation, the local aqueous concentration increases orders of magnitude when a computational cell switches from a reducing to oxidizing condition, which is an artifact of numerical discretization. In principal such artifacts can be reduced to an insignificant level by refining the computational grid. However, this approach is not feasible in typical facility scale applications due to computer runtime and storage limitations. In this paper an alternative sub-grid Tc release model is derived to approximately capture redox processes occurring at scales smaller than the computational mesh. This alternative approach introduces minimal additional computational expense, while significantly reducing numerical artifacts in the form of Tc concentration / flux spikes. The method is illustrated for two simple geometries and the Savannah River Site Saltstone waste Disposal Facility. The sub-grid model is shown to significantly reduce artificial spikes in Tc-99 release, resulting in more physically realistic numerical simulations. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗