Search NASA⌕ Search

SEARCH · Search NASA

Results for “experimental phasing”

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.

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

At least 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Chemistry of Sugar Formation in the Gas Phase: Following the Activated Aldehyde

Sugars are produced by living organisms, and are required building blocks for life as we know it, which raises the foundational question of how sugars formed in a prebiotic environment. The abiotic formose reaction produces sugars from formaldehyde, but our understanding of its initiation step remains murky, with chemists invoking the concept of an “activated aldehyde” to seed this reaction. Singlet hydroxycarbenes, high-energy isomers of aldehydes, were recently reported to facilitate sugar formation under cold, nonaqueous conditions relevant to interstellar environments. Here, we generate singlet methylhydroxycarbene ( 1 CH 3 –C̈–OH) from the photodissociation of pyruvic acid and experimentally measure its gas-phase reaction with d 4 -acetaldehyde using multiplexed photoionization mass spectrometry. The C 4 H 4 D 4 O 2 isomer d 4 -acetoin is the sole product, which we kinetically link to the reactant CH 3 –C̈–OH, and attribute to a carbonyl-ene formation mechanism. We see no evidence of 3-hydroxybutanal, the C–H insertion product expected in carbene chemistry. Using automated exploration we calculate stationary points on the potential energy surface and report master equation rate coefficients from T = 20–600 K, providing quantitative kinetics of this fast reaction for use in chemical models. The prereactive complex in this reaction is stabilized by both hydrogen bonding and electrophilic carbene C═O interactions. These effects create a short-range dynamical bottleneck for the reaction besides the long- and midrange barrierless bottlenecks. Combined with recent reports of 1 HC̈OH production from methanol photodissociation and pyruvic acid production in cold irradiated ices, this work provides evidence that singlet hydroxycarbene + aldehyde chemistry is a feasible path to prebiotic sugar formation.

aldehydes↗
NASA NTRS1986

High-pressure metallization of FeO and implications for the earth's core

The phase diagram of FeO has been experimentally determined to pressures of 155 GPa and temperatures of 4000 K using shock-wave and diamond-cell techniques. A metallic phase of FeO is observed at pressures greater than 70 GPa and temperatures exceeding 1000 K. The metallization of FeO at high pressures implies that oxygen can be present as the light alloying element of the earth's outer core, in accord with the geochemical predictions of Ringwood (1977 and 1979). The high pressures necessary for this metallization suggest that the core has acquired its composition well after the initial stages of the earth's accretion. Direct experimental observations at elevated pressures and temperatures indicate that core-forming alloy can react chemically with oxides such as those forming the mantle. The core and mantle may never have reached complete chemical equilibrium, however. If this is the case, the core-mantle boundary is likely to be a zone of active chemical reactions.

Knittle, Elise↗
NASA NTRS2004

Gas-Liquid Two-Phase Flow Through Packed Beds in Microgravity

Experimental data on flow pattern transitions, pressure drop, and flow characteristics for cocurrent gas–liquid flow through packed columns in microgravity is analyzed. The pulse flow regime exists over a wider range of gas and liquid flow rates under microgravity conditions. Furthermore, maps used to predict transition boundaries in normal gravity do not apply in microgravity. The flow regime data are compared to the widely used Talmor map and a new transition criterion between bubble and pulse flow in microgravity is proposed. The pressure-drop data clearly show that interfacial effects can increase the pressure drop by as much as 300% compared to those predicted by the single-phase Ergun equation. A two-phase friction factor is correlated to the superficial gas and liquid Reynolds numbers and the Suratman number. New data are also presented on the influence of gravity on the pulse amplitude and frequency.

Brian J. Motil↗
NASA NTRS2010

Colorimetric Solid Phase Extraction (CSPE): Using Color to Monitor Spacecraft Water Quality

In August 2009, an experimental water quality monitoring kit based on Colorimetric Solid Phase Extraction (CSPE) technology was delivered to the International Space Station (ISS). The kit, called the Colorimetric Water Quality Monitoring Kit (CWQMK), was launched as a Station Development Test Objective (SDTO) experiment to evaluate the suitability of CSPE technology for routine use monitoring water quality on the ISS. CSPE is a sorption-spectrophotometric technique that combines colorimetric reagents, solid-phase extraction, and diffuse reflectance spectroscopy to quantify trace analytes in water samples. In CSPE, a known volume of sample is metered through a membrane disk that has been impregnated with an analyte-specific colorimetric reagent and any additives required to optimize the formation of the analyte-reagent complex. As the sample flows through the membrane disk, the target analyte is selectively extracted, concentrated, and complexed. Formation of the analyte-reagent complex causes a detectable change in the color of the membrane disk that is proportional to the amount of analyte present in the sample. The analyte is then quantified by measuring the color of the membrane disk surface using a hand-held diffuse reflectance spectrophotometer (DRS). The CWQMK provides the capability to measure the ionic silver (Ag +) and molecular iodine (I2) in water samples on-orbit. These analytes were selected for the evaluation of CSPE technology because they are the biocides used in the potable water storage and distribution systems on the ISS. Biocides are added to the potable water systems on spacecraft to inhibit microbial growth. On the United States (US) segment of the ISS molecular iodine serves as the biocide, while the Russian space agency utilizes silver as a biocide in their systems. In both cases, the biocides must be maintained at a level sufficient to control bacterial growth, but low enough to avoid any negative effects on crew health. For example, the presence of high levels of iodine in water can cause taste and odor issues that result in decreased water consumption by the crew. There are also concerns about potential impacts on thyroid function following exposure to high levels of iodine. With silver, there is a risk of developing argyria, an irreversible blue-gray discoloration of the skin, associated with long term consumption of water containing high concentrations of silver. The need to ensure that safe, effective levels of biocide are maintained in the potable water systems on the ISS provides a perfect platform for evaluating the suitability of CSPE technology for in-flight water quality monitoring. This paper provides an overview of CSPE technology and details on the silver and iodine methods used in the CWQMK. It also reports results obtained during in-flight analyses performed with the CWQMK and briefly discusses other potential applications for CSPE technology in both the spacecraft and terrestrial environments.

Gazda, Daniel B.↗
NASA NTRS2019

The Effect Stacking Fault Segregation and Phase Transformations have on Creep Strength in Ni-based Superalloys

In this study, two commercially similar polycrystalline Ni-based disk superalloys (LSHR and ME3) were creep tested at 760C and 552MPa to approximately 0.3% plastic strain. LSHR consistently displayed superior creep properties at this stress/temperature regime even though the microstructural characteristics between the two alloys were comparable. High resolution structural and chemical analysis, however, revealed significant differences between the two alloys among active gamma prime shearing modes involving superlattice intrinsic and extrinsic stacking faults. In ME3, Co and Cr segregation and Ni and Al depletion were observed along the intrinsic faults - revealing a gamma prime -to- gamma phase transformation. Conversely in LSHR, an alloy with a higher W content, Co and W segregation was observed along the intrinsic faults. This observation combined with scanning transmission electron microscopy (STEM) simulations confirm a gamma prime-to-D019 phase transformation along the intrinsic faults in LSHR. Using experimental observations and density functional theory calculations, a novel local phase transformation strengthening mechanism is proposed that could be further utilized to improve the high temperature creep capabilities of Ni-base disk alloys.

Superalloy↗
DOE OSTI2025

An Integrated High-Speed Microstructural Characterization Method Using Simultaneous XRD, Stereo-DIC, and PCI

High-speed characterization of the deformation mechanisms in polycrystalline metals requires the quantification of full strain fields and local microstructural evolutions simultaneously. In this paper, we present a novel experimental method to integrate phase-contrast imaging (PCI), stereographic digital image correlation (stereo-DIC), and full-ring X-ray diffraction (XRD) to allow for the simultaneous characterization of polycrystalline metals at 1MHz or higher. A Kolsky bar was integrated into the synchrotron X-ray source in Sector 32 ID-B at the Advance Photon Source (APS) at Argonne National Laboratory. When the sample is dynamically loaded, the diagnostic methods of full-ring XRD, PCI, and stereo-DIC are properly synchronized to record the deformation behavior at both continuum and microstructural scales as a function of the loading history. An advanced high-strength steel (AHSS) is used as a model material to demonstrate the capabilities of this new experimental method.

36 MATERIALS SCIENCE↗
DOE OSTI2024

3D Ferroelectric Phase Field Simulations of Polycrystalline Multi‐Phase Hafnia and Zirconia Based Ultra‐Thin Films

Abstract HfO 2 – and ZrO 2 –based ferroelectric thin films have emerged as promising candidates for the gate oxides of next‐generation electronic devices. Recent work has experimentally demonstrated that a tetragonal/orthorhombic (t/o‐) phase mixture with partially in‐plane polarization can lead to negative capacitance (NC) stabilization. However, there is a discrepancy between experiments and the theoretical understanding of domain formation and domain wall motion in these multi‐phase, polycrystalline materials. Furthermore, the effect of anisotropic domain wall coupling on NC has not been studied so far. Here, 3D phase field simulations of HfO 2 – and ZrO 2 –based mixed‐phase ultra‐thin films on silicon are applied to understand the necessary and beneficial conditions for NC stabilization. It is found that smaller ferroelectric grains and a larger angle of the polar axis with respect to the out‐of‐plane direction enhances the NC effect. Furthermore, it is shown that theoretically predicted negative domain wall coupling even along only one axis prevents NC stabilization. Therefore, it is concluded that topological domain walls play a critical role in experimentally observed NC phenomena in HfO 2 – and ZrO 2 –based ferroelectrics.

30 DIRECT ENERGY CONVERSION↗
NASA NTRS1990

Modeling of collision and coalescence of droplets during microgravity processing of Zn-Bi immiscible alloys

A population balance model is presented for the coarsening of the dispersed phase of liquid-liquid two-phase mixtures in microgravity due to gravity sedimentation and Marangoni migration, which lead to the collision and coalescence of droplets. The model is used to predict the evolution of the size distribution of the dispersed phase in a liquid-phase miscibility gap system, Zn-Bi, which has been used in a number of experimental microgravity processing studies in which significant phase segregation has been observed. The analysis shows that increasing the temperature gradient, gravity level, volume fraction of the dispersed phase, initial average drop radius, initial standard deviation of droplet radii, or the temperature coefficient of the interfacial tension leads to an increase in the rate of droplet growth due to collision and coalescence. Comparison of the distribution evolutions for unimodal and bimodal initial distributions shows that the latter yield significantly more rapid droplet growth. Finally, it is shown that droplet growth can be dramatically reduced with antiparallel orientation of the gravity vector and the temperature gradient, provided that the relative magnitude of these two vectors is properly chosen.

Davis, R. H.↗
DOE OSTI2024

Understanding the High-Temperature Deformation Behaviors in Additively Manufactured Al6061+TiC Composites via In Situ Neutron Diffraction

Aluminum matrix composites (AMCs) are designed to enhance the performance of conventional aluminum alloys for engineering applications at both room and elevated temperatures. However, the dynamic phase-specific deformation behavior and load-sharing mechanisms of AMCs at elevated temperatures have not been extensively studied and remain unclear. Here, in situ neutron diffraction experiments are employed to reveal the phase-specific structure evolution of additively manufactured Al6061+TiC composites under compressive loading at 250 °C. It is found that the addition of a small amount of nano-size TiC significantly alters the deformation behavior and increases the strength at 250 °C in comparison to the as-printed Al6061. Unlike the two-stage behavior observed in Al6061, the Al6061+TiC composites exhibit three stages during compression triggered by changes in the interphase stress states. Further analysis of Bragg peak intensity and broadening reveals that the presence of TiC alters the dislocation activity during deformation at 250 °C by influencing dislocation slip planes and promoting dislocation accumulation. These findings provide direct experimental observations of the phase-specific dynamic process in AMCs under deformation at an elevated temperature. The revealed mechanisms provide insights for the future design and optimization of high-performance AMCs.

36 MATERIALS SCIENCE↗
NASA NTRS2003

Catalyzed Combustion of Bipropellants for Micro-Spacecraft Propulsion

This paper addresses the need to understand the physics and chemistry involved in propellant combustion processes in micro-scale combustors for propulsion systems on micro-spacecraft. These spacecraft are planned to have a mass less than 50 kilograms with attitude control estimated to be in the 10 milli-Newton thrust class. These combustors are anticipated to be manufactured using Micro Electrical Mechanical Systems (MEMS) technology and are expected to have diameters approaching the quenching diameter of the propellants. Combustors of this size are expected to benefit significantly from surface catalysis processes. Miniature flame tube apparatus is chosen for this study because microtubes can be easily fabricated from known catalyst materials and their simplicity in geometry can be used in fundamental simulations for validation purposes. Experimentally, we investigated the role of catalytically active surfaces within 0.4 and 0.8 mm internal diameter microtubes, with special emphases on ignition processes in fuel rich gaseous hydrogen and gaseous oxygen. Flame thickness and reaction zone thickness calculations predict that the diameters of our test apparatus are below the quenching diameter of the propellants in sub-atmospheric tests. Temperature and pressure rise in resistively heated platinum and palladium microtubes was used as an indication of exothermic reactions. Specific data on mass flow versus preheat temperature required to achieve ignition are presented. With a plug flow model, the experimental conditions were simulated with detailed gas-phase chemistry, thermodynamic properties, and surface kinetics. Computational results generally support the experimental findings, but suggest an experimental mapping of the exit temperature and composition is needed.

Schneider, Steven J.↗
NASA NTRS2015

CarbAl Heat Transfer Material

The increasing use of power electronics, such as high-current semiconductor devices and modules, within space vehicles is driving the need to develop specialty thermal management materials in both the packaging of these discrete devices and the packaging of modules consisting of these device arrays. Developed by Applied Nanotech, Inc. (ANI), CarbAl heat transfer material is uniquely characterized by its low density, high thermal diffusivity, and high thermal conductivity. Its coefficient of thermal expansion (CTE) is similar to most power electronic materials, making it an effective base plate substrate for state-of-the-art silicon carbide (SiC) super junction transistors. The material currently is being used to optimize hybrid vehicle inverter packaging. Adapting CarbAl-based substrates to space applications was a major focus of the SBIR project work. In Phase I, ANI completed modeling and experimentation to validate its deployment in a space environment. Key parameters related to cryogenic temperature scaling of CTE, thermal conductivity, and mechanical strength. In Phase II, the company concentrated on improving heat sinks and thermally conductive circuit boards for power electronic applications.

Fink, Richard↗
NASA NTRS2019

Tonal Noise Control Using Rotor Phase Synchronization

The purpose of this study is to determine if phase synchronization can be used to reduce the net radiated sound power from two rotors. Phase synchronization implies that the rotors have the same rotational speed with a fixed relative azimuthal blade position, or phase. The concept is evaluated both experimentally and numerically. Measurements of source directivity and thrust are initially compared with predictions to confirm that the model accurately captures the relevant trends. The model is then used to explore the design space and identify relevant parameters. Both experimental and numerical results show that the radiated sound power at the blade passage frequency can be reduced by appropriately controlling the relative azimuthal phase of the rotors. Vehicle level predictions are also provided for a notional octocopter, comparing two different modes of operation. Predictions show that phase synchronization can be used to achieve a 4-5 dB reduction of the sound pressure level at the blade passage frequency nearly everywhere on the ground plane beneath the vehicle.

Noah H Schiller↗
DOE OSTI2024

Thermal-hydraulic Performance of Emerging Low GWP Refrigerant Mixture under Flow Boiling in Brazed Plate Heat Exchangers

The hydrofluorocarbon (HFC) refrigerants used in the current refrigeration systems are facing a phase-down due to their higher greenhouse effect resulting in global warming, and thus HVAC&R industry has undergone a transition to low Global Warming Potential (GWP) refrigerants. Refrigerant mixtures are attractive alternatives since their composition can be tailored to comply with environmental regulations while preserving favorable thermophysical properties. However, the new low-GWP zeotropic mixture refrigerants have two or more components with different saturation temperatures at the same pressure level, known as temperature glide, which can cause the degradation of the overall heat transfer performance. The brazed plate heat exchangers (BPHX) provide excellent heat transfer performance due to a compact design and are used in several air-conditioning and refrigeration applications. In this study, flow boiling heat transfer and the associated pressure drop of the refrigerant mixture in a vertical BPHX were experimentally investigated. The single-phase water-to-water experiments were conducted in the tested heat exchanger with a counter-flow configuration. The flow boiling experiments charged with R-134a and R-454C were then performed in a pumped refrigerant loop to evaluate its thermal-hydraulic performance. Furthermore, parametric studies of various heat fluxes, mass fluxes, vapor qualities, and saturation temperatures were also conducted.

Yang, Cheng-Min↗
NASA NTRS1991

A statistical approach to the brittle fracture of a multi-phase solid

A stochastic damage model is proposed to quantify the inherent statistical distribution of the fracture toughness of a brittle, multi-phase solid. The model, based on the macrocrack-microcrack interaction, incorporates uncertainties in locations and orientations of microcracks. Due to the high concentration of microcracks near the macro-tip, a higher order analysis based on traction boundary integral equations is formulated first for an arbitrary array of cracks. The effects of uncertainties in locations and orientations of microcracks at a macro-tip are analyzed quantitatively by using the boundary integral equations method in conjunction with the computer simulation of the random microcrack array. The short range interactions resulting from surrounding microcracks closet to the main crack tip are investigated. The effects of microcrack density parameter are also explored in the present study. The validity of the present model is demonstrated by comparing its statistical output with the Neville distribution function, which gives correct fits to sets of experimental data from multi-phase solids.

Liu, W. K.↗
NASA NTRS1972

Experimental Hingeless Rotor Characteristics at Full Scale First Flap Mode Frequencies (including Rotor Frequency Response to Shaft Oscillations), Phase 3

The completion of the High Advance Ratio Research Program is reported. The primary objectives of the program were to experimentally determine the rotor frequency response to shaft pitching and rolling oscillations and to acquire steady response and frequency response data at high advance ratios for hingeless rotors with typical, full-scale, first flap mode natural frequencies. Secondary objectives of the program included the further evaluation of both the hub moment feedback control system and the simplified rigid blade flapping theory with respect to shaft oscillations. The bulk of the text is devoted to the presentation and examination of representative experimental results. All the analyzed test data are documented in tabular and/or graphical formats.

Kuczynski, W. A.↗
DOE OSTI2024

Interactions of laser-driven tin ejecta microjets over phase transition boundaries

Ejecta microjets offer an experimental methodology to study high-speed particle laden-flow interactions, as microjets consist of millions of particulates traveling at velocities of several kilometers per second and are easily generated by most common shock drives. Previous experiments on the OMEGA Extended Performance laser found that collisions between two counter-propagating laser-driven tin ejecta microjets varied as a function of drive pressure; jets generated near shock pressures of 10 GPa passed through each other without interacting, whereas jets generated at shock pressures of over 100 GPa interacted strongly, forming a cloud around the center interaction point. In this paper, we present a more systematic scan of tin ejecta microjet collisions over intermediate pressure regimes to identify how and at what shock pressure interaction behavior onsets. Radiographs of interacting microjets at five different laser drive energies qualitatively demonstrate that interaction behavior onsets slowly as a function of laser drive energy. Quantitative mass and density metrics from each radiograph provide trends on jet characteristics and collisional mass dispersion. It is observed that jetting mass, jet densities, and mass dispersion increase with increasing drive pressures and that the increased jet density at the higher drive energies may account for the increased mass dispersion. This work provides an important step in the understanding of tin ejecta microjet collisions and paves the way for future studies on the physics dominating high-speed particle-laden flow interactions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗