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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 937 records · Page 52
All sourcesNASA NTRSDOE OSTI
NASA NTRS2023

Modeling Fuel Droplets in RCS Engine Exhaust Plume

Thrusters are used to maneuver spacecraft in space. Spacecraft maneuvering and attitude control is achieved by accelerating the high temperature and pressure exhaust gases, which are the result of chemical combustion in the case of chemical engines, through the rocket nozzle. Following the end of the nozzle a plume is created containing combustion gases and high velocity droplets of unburnt propellant that with time can erode the surfaces it strikes. A simulation that can accurately model a thruster’s plume can help us reduce the erosion of components struck by the plume. The creation of this simulation can be broken into several parts, and this paper focuses on finding out what distribution of particles along a plane in the nozzle, where combustion can be assumed to be complete, creates the observed particle distribution in the plume. Findings show that unburnt droplets are mostly concentrated in the center of the nozzle or uniformly dispersed within the nozzle.

CFD↗
NASA NTRS2024

General Circulation Models Simulate Negative Liquid Water Path­–Droplet Number Correlations, but Anthropogenic Aerosols Still Increase Simulated Liquid Water Path

General circulation models' (GCMs) estimates of the liquid water path adjustment to anthropogenic aerosol emissions differ in sign from other lines of evidence. This reduces confidence in estimates of the effective radiative forcing of the climate by aerosol–cloud interactions (ERFaci). The discrepancy is thought to stem in part from GCMs' inability to represent the turbulence–microphysics interactions in cloud-top entrainment, a mechanism that leads to a reduction in liquid water in response to an anthropogenic increase in aerosols. In the real atmosphere, enhanced cloud-top entrainment is thought to be the dominant adjustment mechanism for liquid water path, weakening the overall ERFaci. We show that the latest generation of GCMs includes models that produce a negative correlation between the present-day cloud droplet number and liquid water path, a key piece of observational evidence supporting liquid water path reduction by anthropogenic aerosols and one that earlier-generation GCMs could not reproduce. However, even in GCMs with this negative correlation, the increase in anthropogenic aerosols from preindustrial to present-day values still leads to an increase in the simulated liquid water path due to the parameterized precipitation suppression mechanism. This adds to the evidence that correlations in the present-day climate are not necessarily causal. We investigate sources of confounding to explain the noncausal correlation between liquid water path and droplet number. These results are a reminder that assessments of climate parameters based on multiple lines of evidence must carefully consider the complementary strengths of different lines when the lines disagree.

General circulation models↗
DOE OSTI2014

Chip-based droplet sorting

A non-contact system for sorting monodisperse water-in-oil emulsion droplets in a microfluidic device based on the droplet's contents and their interaction with an applied electromagnetic field or by identification and sorting.

42 ENGINEERING↗
DOE OSTI2012

Simulation of film and droplet flow on wide aperture fractures using Smoothed Particle Hydrodynamics

Simulation of flow in fractured porous media represents a challenge due to the highly non-linear dynamics of fluid-air interfaces. Here we present small-scale flow simulations on wide aperture fractures using a modified three-dimensional multiphase SPH model \cite{Tartakovsky2005}. The model is modified to include the effects of random thermal noise. The model is able to reproduce a wide range of wetting conditions and Reynolds numbers encountered in laboratory experiments using pairwise fluid-fluid and solid-fluid interaction forces. Static and transient flow dynamics are compared to empirical and semianalytical solutions: (1) Droplets in a critical state are in agreement with laboratory experiments of \cite{ElSherbini2004}. (2) Well-defined random thermal noise is introduced via the fluctuation-dissipation theorem and its effect on dynamics of droplets in a critical state is investigated. (3) Transient flow dynamics on dry surfaces are validated using the dimensionless relationships established by \cite{Podgorski2001} and compared to (4) dynamics on prewetted surfaces where flow velocities are shown to be nearly tripled. Finally we establish flow regimes and occurrence of trailing films on initially dry fracture surfaces based on dimensionless scaling parameters and Reynolds numbers.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2017

Chip-based droplet sorting

A non-contact system for sorting monodisperse water-in-oil emulsion droplets in a microfluidic device based on the droplet's contents and their interaction with an applied electromagnetic field or by identification and sorting.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Validation of CTF Droplet Entrainment and Annular/Mist Closure Models using Riso Steam/Water Experiments

This document summarizes the work to validate the droplet entrainment and de-entrainment models, as well as two-phase closure models in the CTF code [1] by comparison with experimental data obtained at Risø National Laboratory [2]. CTF is the modernized version of the subchannel code, COBRA-TF [3], being jointly developed by Oak Ridge National Laboratory and North Carolina State University for applications in the Consortium for Advanced Simulation of Light Water Reactors (CASL). The Risø data included a series of more than 250 steam/water experiments that were performed in both tube and annulus geometries over a range of various pressures and outlet qualities. Experimental conditions wereset so that the majority of cases were in the annular/mist flow regime. Measurements included liquid film flow rate, droplet flow rate, film thickness, and two-phase pressure drop. CTF was used to model 180 of the tubular geometry cases, matching experimental geometry, outlet pressure, and outlet flow quality to experimental values. CTF results were compared to the experimental data at the outlet of the test section in terms of vapor flow fractions, and entrained liquid flow fractions, and pressure drop per unit length.

Wysocki, Aaron↗
DOE OSTI2019

Droplet generating rotating cutters

A device for producing droplets is disclosed. A disk assembly comprising a first disk mounted to a second disk is provided. The first disk comprises first openings. The second disk comprises second openings. The first openings and the second openings alternately align with one another such that, as a liquid passes through the first openings and the second openings, the liquid falls as a droplet as the first openings and the second openings skew apart.

42 ENGINEERING↗
DOE OSTI2023

TWST Cloud Properties (COD, droplet effective radius, and thermodynamic phase). SAIL, AMF2, 2022-2023.

The dataset consists of calibrated zenith shortwave spectral radiances (440-1700 nm) and cloud optical depth (COD) retrievals approximately every second. Retrievals of cloud droplet effective radius and thermodynamic phase are currently done offline, but some of these retrievals are included in the dataset. Effective radius and phase are included for days with periods of sufficiently high COD. Effective radius and phase retrievals in the data set were computed at approximately 5-10 second intervals to reduce computation time. The retrievals can be performed at the full sample rate. The field of view is 0.5 degree.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Disentangling Memristive and Memcapacitive Effects in Droplet Interface Bilayers Using Dynamic Impedance Spectroscopy

The underlying principles for generating intelligent behavior in living organisms are fundamentally different from those in traditional solid-state circuits. Biomimetic neuromorphic equivalents based on biological membranes offer novel implementation of tunable plasticity and diverse mechanisms to control functionality. Here, dynamic electrochemical impedance spectroscopy (dEIS) to probe diphytanoylphosphatidylcholine (DPhPC) droplet interface bilayers (DIBs) to better understand the differences in molecular level structure/dynamics that give rise to hysteretic loops and neuromorphic, memelement behaviors in lipid bilayers in response to electrical biasing is used. Importantly, this system does not have ion-conducting channels and is, therefore, not expected to show memristive behavior. Surprisingly, both memristive and memcapacitive behaviors by measuring the time-dependent complex impedance of DPhPC DIBs are detected. Furthermore, it is shown that nonlinear memristance can originate from structural changes in the bilayer, affecting its dielectric properties. This novel dEIS application allows for the simultaneous analysis of the system's changing memristive and memcapacitive properties, which originate from different molecular restructuring processes. Moreover, and importantly, access to this type of information increases the number of neuromorphic processes supported simultaneously in a single two-terminal device.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Disposable Biosensor Based on Amidase/CeO2/GNR Modified Inkjet-printed CNT Electrodes-droplet Based Paracetamol Detection in Biological Fluids for “Point-of-care” Applications

A disposable acetaminophen biosensor based on inkjet-printed CNT electrodes (IJPCNT) modified with amidase/cerium dioxide@graphene nanoribbons composite was developed (ACeO2@GNR/IJPCNT). The enzyme amidase A was used for the first time as a recognition element. Inkjet-printed CNT electrodes served as a basis for the construction of a biosensor that enables droplet detection using 5 μL sample volume. The biosensor showed high selectivity, sensitivity, a low detection limit of 0.18 μM and a wide working linear range from 1 to 100 μM. The proposed approach allows fast and reliable detection of acetaminophen in biological fluids with negligible matrix effect and remarkable reproducibility. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Dephosphorization of Levitated Silicon-Iron Droplets for Production of Solar-Grade Silicon

The treatment of relatively inexpensive silicon-iron alloys is a potential refining route in order to generate solar-grade silicon. Phosphorus is one of the more difficult impurity elements to remove by conventional processing. In this study, electromagnetic levitation was used to investigate phosphorus behavior in silicon-iron alloy droplets exposed to H{sub 2}-Ar gas mixtures under various experimental conditions including, refining time, temperature (1723 K to 1993 K), gas flow rate, iron content, and initial phosphorus concentration in the alloy. Thermodynamic modeling of the dephosphorization reaction permitted prediction of the various gaseous products and indicated that diatomic phosphorus is the dominant species formed.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Linkage between lipid droplet formation and nuclear deformation in HeLa human cervical cancer cells

Highlights: • Oleic acid (OA) induces cytoplasmic, but not nucleoplasmic, LDs in HeLa cells. • Cells harboring OA-induced cytoplasmic LDs exhibit deformity of the nucleus. • Multinucleation by paclitaxel and reversine treatment coincides with LD formation. • LD formation and nuclear deformation are mutually affectable. Because lipid droplets (LDs) and the nucleus are cellular organelles that regulate seemingly very different biochemical processes, very little attention has been focused on their possible interplay. Here, we report a correlation between nuclear morphology and cytoplasmic LD formation in HeLa human cervical cells. When the cells were treated with oleic acid (OA), LDs were formed in the cytoplasm, but not in the nucleoplasm. Interestingly, cells harboring OA-induced cytoplasmic LDs showed deformity of the nucleus, particularly at the nuclear rim. Conversely, when alteration from a single spherical nuclear shape to a multinucleated form was enforced by coadministration of paclitaxel and reversine, a significant amount of LDs was detected in the cytoplasm of the multinucleated cells. These two distinct pharmacological culture conditions not only allow analysis of the previously underappreciated organelle relationship, but also provide insights into the mutual affectability of LD formation and nuclear deformation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Quantitation of repaglinide and metabolites in mouse whole-body thin tissue sections using droplet-based liquid microjunction surface sampling-high-performance liquid chromatography-electrospray ionization tandem mass spectrometry

Herein, quantitation aspects of a fully automated autosampler/HPLC-MS/MS system applied for unattended droplet-based surface sampling of repaglinide dosed thin tissue sections with subsequent HPLC separation and mass spectrometric analysis of parent drug and various drug metabolites was studied. Major organs (brain, lung, liver, kidney, muscle) from whole-body thin tissue sections and corresponding organ homogenates prepared from repaglinide dosed mice were sampled by surface sampling and by bulk extraction, respectively, and analyzed by HPLC-MS/MS. A semi-quantitative agreement between data obtained by surface sampling and that by employing organ homogenate extraction was observed. Drug concentrations obtained by the two methods followed the same patterns for post-dose time points (0.25, 0.5, 1 and 2 h). Drug amounts determined in the specific tissues was typically higher when analyzing extracts from the organ homogenates. Furthermore, relative comparison of the levels of individual metabolites between the two analytical methods also revealed good semi-quantitative agreement.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

A Proximity Labeling Strategy Provides Insights into the Composition and Dynamics of Lipid Droplet Proteomes

Lipid droplet (LD) functions are regulated by a complement of integral and peripheral proteins that associate with the bounding LD phospholipid monolayer. Defining the composition of the LD proteome has remained a challenge due to the presence of contaminating proteins in LD-enriched buoyant fractions. To overcome this limitation, we developed a proximity labeling strategy that exploits LD-targeted APEX2 to biotinylate LD proteins in living cells. Application of this approach to two different cell types identified the vast majority of previously validated LD proteins, excluded common contaminating proteins, and revealed new LD proteins. Moreover, quantitative analysis of LD proteome dynamics uncovered a role for endoplasmic reticulum-associated degradation in controlling the composition of the LD proteome. In conclusion, these data provide an important resource for future LD studies and demonstrate the utility of proximity labeling to study the regulation of LD proteomes.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Using Thermodynamic Availability to Predict the Transitional Film Reynolds Number between the Droplet and Jet Modes in Falling Liquid between Horizontal Tubes

The objective of this paper is to propose and validate a model for predicting the transitional film Reynolds number between the droplet and jet modes of falling film flows. The proposed model relies on thermodynamic availability with no fitting to mode transition data. The model directly predicts the numerical values of the transitional film Reynolds numbers at different operating conditions. The results of the model are validated against 43 experimental data points from the literature, which cover 10 working fluids and a wide range of tube geometries. The accuracy of the proposed model in predicting the validation data is -on average- more than 20 % better than that of the widely used Re = a (Ga) b and Re = a (Ga) b (S/ξ) c models. The model also achieves low computation time (less than 30 seconds for the 43 validation data points). The model presented in this paper has the potential of integration with heat transfer, mass transfer, and pressure drop models for optimizing the design and operation of falling film heat and mass exchangers.

42 ENGINEERING↗
DOE OSTI2020

Lipid droplets in plants and algae: Distribution, formation, turnover and function

We report plant oils represent an energy-rich and carbon-dense group of hydrophobic compounds. These oils are not only of economic interest, but also play important, fundamental roles in plant and algal growth and development. The subcellular storage compartments of plant lipids, referred to as lipid droplets (LDs), have long been considered relatively inert oil vessels. However, research in the last decade has revealed that LDs play far more dynamic roles in plant biology than previously appreciated, including transient neutral lipid storage, membrane remodeling, lipid signaling, and stress responses. Here we discuss recent developments in the understanding of LD formation, turnover and function in land plants and algae.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Distinct Impacts of Increased Aerosols on Cloud Droplet Number Concentration of Stratus/Stratocumulus and Cumulus

In situ aircraft measurements obtained during the RACORO field campaign are analyzed to study the aerosol effects on different cloud regimes. Here, the results show that with increasing cloud condensation nuclei (CCN), cloud droplet number concentration ( N d ) significantly increases in stratocumulus (Sc) while remains almost unchanged in cumulus (Cu). By using a new approach to strictly constrain the dynamics in Cu, we found that neither simultaneously changing cloud dynamics nor dilution of cloud water induced by entrainment-mixing can explain the observed insensitivity of N d . The different degree of reduction in cloud supersaturation caused by increasing aerosols might be responsible for the observed different aerosol indirect effect between Sc and Cu.

54 ENVIRONMENTAL SCIENCES↗