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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 1,225 records · Page 68
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Measurement of maximum strain of steel beam structures based on average strains from vibrating wire strain gages

In structural health monitoring, the safety of steel beam structures can be assessed by comparing the measured maximum stress and the allowable stress of the beam calculated by a design code. For the case of a steel beam subjected to variable lateral loadings, many difficulties exist in measuring the maximum stress in a beam with point sensors that can measure the strain only at a local point of a beam since the location and magnitude of the maximum stress induced in a beam by the loading change. Although traditional strain sensors can measure the strain only at a local point, a vibrating wire strain gage (VWSG) that measures integrated strains over its gage length can consider the variation of strains due to variable loadings. This paper presents an estimation model to determine the maximum strains or stresses in a steel beam based on average strains measured using VWSGs. The model is derived by defining the relation between the average strains measured using VWSGs and the maximum strains of beams. The model is experimentally tested by comparing the maximum strain directly obtained from electrical strain gages and the estimated maximum strain based on the average strain from VWSGs.

42 ENGINEERING↗
DOE OSTI2021

Ultra-High Temperature Thermal Conductivity Measurements of a Reactive Magnesium Manganese Oxide Porous Bed Using a Transient Hot Wire Method

Pelletized magnesium manganese oxide shows promise for high temperature thermochemical energy storage. It can be thermally reduced in the temperature range between 1250 °C and 1500 °C and re-oxidized with air at typical gas-turbine inlet pressures (1–25 bar) in the temperature range between 600 °C and 1500 °C. The combined thermal and chemical volumetric energy density is approximately 2300 MJ/m3. The rate at which a thermochemical storage module can be charged is limited by heat transfer inside the solid packed bed. Hence, the effective thermal conductivity of packed beds of magnesium-manganese oxide pellets is a crucial parameter for engineering Mg-Mn-O redox storage devices. We have measured the effective thermal conductivity of a packed bed of 3.66 ± 0.516 mm sized magnesium manganese oxide (Mn to Mg molar ratio of 1:1) pellets in the temperature range of 300–1400 °C. Since the material is electrically conductive at temperatures above 600 °C, the sheathed transient hot wire method is used for measurements. Raw data is analyzed using the Blackwell solution to extract the bed thermal conductivity. The effective thermal conductivity standard deviation is less than 10% for a minimum of three repeat measurements at each temperature. Experimental results show an increase in the effective thermal conductivity with temperature from 0.50 W/m °C around 300 °C to 1.81 W/m °C close to 1400 °C. We propose a dual porosity model to express the effective thermal conductivity as a function of temperature. This model also considers the effect of radiation within the bed, as this is the dominant heat transfer mode at high temperatures. The proposed model accounts for microscale pellet porosity, macroscale bed porosity, pellet size, solid thermal conductivity (phonon transport), and radiation (photon transport). The coefficient of determination between the proposed model and the experimental results is greater than 0.90.

Engineering↗
DOE OSTI2022

Analysis of Conduction Cooling Strategies for Wire Arc Additive Manufacturing

Metal additive manufacturing (AM) processing consists of numerous parameters which take time to optimize for various geometries. One aspect of the metal AM process that continues to be explored is the control of thermal energy accumulation during component manufacturing due to the melting and solidification of the feedstock. Excessive energy accumulation causes thermal failure of the component while minimal energy accumulation causes lack of fusion with the build plate or previous layer. The ability to simulate the thermal response of an AM component can increase research efficiency by reducing the time to optimize thermal energy accumulation. This paper presents an effective implementation of finite element analysis to determine the thermal response of a wire arc additive manufactured component with various build plate sizes and cooling methods including, integral build plate cooling, oversized build plates with passive cooling, and non-integral build plate cooling. The use of integral build plate cooling channels was shown to decrease the interpass temperature at the conclusion of the build process by 55% and build plate temperature by 96% compared to the conventionally deposited sample with 20 second dwell time. The use of a tall build plate with passive cooling was shown to reduce the interpass temperature by 32% as compared to the conventionally deposited sample with 20 second dwell time. Each cooling strategy evaluated decreased the interpass temperature within a range of 20–55% which enables higher deposition rates and decreased dwell times during depositions. The cooling strategies are designed to be implemented in a hybrid or retrofit AM platform to mitigate concerns of the thermal input from the additive process having detrimental effects on the precision of the machining process. This paper shows that accurate simulations of all strategies can be used to accurately predict the thermal response of the various strategies discussed. These cooling strategies will allow for increased deposition rates with comparable interpass temperature and decreased dwell time, increasing deposition efficiency. This model and these simulations are verified by experimental results. It is concluded that passive strategies, such as the over-sized tall build plate, can be used when liquid coolant in the AM environment could negatively affect the deposition process. Active cooling strategies, such as the integral build plate cooling could be used if low thermal conductivity materials are deposited or higher material deposition rates are desired. This paper discusses the use of active and passive cooling used during AM and shows how a simulation model can be used to make design choices for cooling strategies. The model also enables verification of select critical process parameters such as dwell times for a desired interpass temperature.

Heinrich, Lauren↗
DOE OSTI2023

Mechanical responses of 316L stainless steel printed by wire arc additive manufacturing with different thermal histories

In this paper, 316L stainless steel walls were printed using single-bead pass and multiple-bead pass wire arc additive manufacturing (WAAM), which represent the internal basket wall and external wall of a spent nuclear fuel (SNF) canister; respectively. Scanning electron microscopy (SEM) microstructure characterization and tensile tests at room temperature (21 °C) and elevated temperature (250 °C) were performed on specimens extracted along the length and height directions of the printed walls. Results showed that grain morphology, grain angles, and retained ferrite are different between the two printed walls, which received different heat input in WAAM. The single-bead pass printed wall exhibited higher yield strength than the multiple-bead pass printed wall because of more retained ferrite and larger portion of random-high angle boundaries (RHAB) grains.

Tang, Wei↗
DOE OSTI2016

Conditions of growth of high-quality relaxed Si{sub 1–x}Ge{sub x} layers with a high Ge content by the vapor-phase decomposition of monogermane on a sublimating Si hot wire

The conditions of the epitaxial growth of high-quality relaxed Si{sub 1–x}Ge{sub x} layers by the combined method of the sublimation molecular-beam epitaxy and vapor-phase decomposition of monogermane on a hot wire are considered. The combined growth procedure proposed provides a means for growing Si{sub 1–x}Ge{sub x} layers with a thickness of up to 2 µm and larger. At reduced growth temperatures (T{sub S} = 325–350°C), the procedure allows the growth of Si{sub 1–x}Ge{sub x} layers with a small surface roughness (rms ≈ 2 nm) and a low density of threading dislocations. The photoluminescence intensity of Si{sub 1–x}Ge{sub x}:Er layers is significantly (more than five times) higher than the photoluminescence intensity of layers produced under standard growth conditions (T{sub S} ≈ 500°C) and possess an external quantum efficiency estimated at a level of ~0.4%.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Interaction between graphene and metamaterials: split rings vs. wire pairs

We have recently shown that graphene is unsuitable to replace metals in the current-carrying elements of metamaterials. At the other hand, experiments have demonstrated that a layer of graphene can modify the optical response of a metal-based metamaterial. Here we study this electromagnetic interaction between metamaterials and graphene. We show that the weak optical response of graphene can be modified dramatically by coupling to the strong resonant fields in metallic structures. A crucial element determining the interaction strength is the orientation of the resonant fields. If the resonant electric field is predominantly parallel to the graphene sheet (e.g., in a complementary split-ring metamaterial), the metamaterial’s resonance can be strongly damped. If the resonant field is predominantly perpendicular to the graphene sheet (e.g., in a wire-pair metamaterial), no significant interaction exists.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Improvement of Wire-Stretching Technique to the RF Measurements of E-Center and Multipole Field for the Dipole Cavities

After the first publication [1] of wire-stretching technique from its principle to measure the electrical center of a deflecting cavity, more refinements of this techniques including the review of its analytical and simulation results, RF circuit improvement the signal to noise ratio and its application to other cavities have been developed. These applications include the electrical center measurements for the LHC RFD and DQW crabbing cavity prototypes, multi-frequency harmonic kicker cavity for JLEIC electron cooler [2], TE011 cavity developed for the beam magnetization measurement [3], and a separator cavity at BNL [4].

Park, Gunn T.↗
DOE OSTI2019

Magnetic Measurement With Single Stretched Wire Method on SuperKEKB Final Focus Quadrupoles

Superconducting-final-focus-quadrupole magnet system (QCS) were installed on an interaction region (IR) of SuperKEKB on Feb. 2017. The QCS consists of eight quadrupole magnets and four compensation solenoids; these magnets are contained in the two cryostats and are installed into Belle II detector which generates a solenoid field of 1.5 T. We determined the quadrupole centers with respect to accelerator beam lines with a single stretched wire (SSW) method. Here the results of the magnetic measurement with SSW are presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

Electrical Core Transformer for Grid Improvement Incorporating Wire Magnetic Components

The research reported herein adds to the understanding of oil-immersed distribution transformers by exploring and demonstrating potential improvements in efficiency and cost utilizing the unique Buswell approach wherein the unit is redesigned, replacing magnetic sheet with wire allowing for improvements in configuration and increased simplicity in the build process. Exploration of new designs is a critical component in our drive to assure reduction of energy waste, adequate delivery to the citizenry, and the robustness of U.S. manufacturing. By moving that conversation forward, this exploration adds greatly to our base of knowledge and clearly outlines an important avenue for further exploration. This final report shows several advantages of this new transformer type (outlined in a report signed by all of our collaborating partners and included in this document). Although materials development is required to achieve commercial potential, the clear benefits of the technology if that development were a given is established. Exploration of new transformer types and further work on the Buswell design approach is in the best interest of the public, industry, and the United States. Public benefits accrue from design alternatives that reduce the overall use of energy, but it must be acknowledged that new DOE energy efficiency standards have provided some assurance in that regard. Nonetheless the burden of achieving these new standards has been largely shifted to the manufacturers of oil-immersed distribution transformers with cost increasing up to 20% of some units versus 2006 when this investigation was started. Further, rising costs have forced the industry to look closely are far more expensive technologies which may threaten U.S. competitiveness in the distribution transformer market. This concern is coupled with the realization that many units in the nation's grid are beyond their optimal life which suggests that the nation may be headed for an infrastructure crisis that U.S. industry is ill prepared to handle which could further challenge U.S. competitiveness.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

Assessment of Proton Deflectometry for Exploding Wire Experiments

This project provides the first demonstration of the application of proton deflectometry for the diagnosis of electromagnetic field topology and current-carrying regions in Z-pinch plasma experiments. Over the course of this project several milestones were achieved. High-energy proton beam generation was demonstrated on the short-pulse high-intensity Leopard laser, (10 Joules in ~350 femtoseconds, and the proton beam generation was shown to be reproducible. Next, protons were used to probe the electromagnetic field structure of short circuit loads in order to benchmark the two numerical codes, the resistive-magnetohydrodynamics (MHD) code, Gorgon, and the hybrid particle-in-cell code, LSP for the interpretation of results. Lastly, the proton deflectometry technique was used to map the magnetic field structure of pulsed-power-driven plasma loads including wires and supersonic jets formed with metallic foils. Good agreement between the modeling and experiments has been obtained. The demonstrated technique holds great promise to significantly improve the understanding of current flow and electromagnetic field topology in pulsed power driven high energy density plasmas. Proton probing with a high intensity laser was for the first time implemented in the presence of the harsh debris and x-ray producing z-pinch environment driven by a mega-ampere-scale pulsed-power machine. The intellectual merit of the program was that it investigated strongly driven MHD systems and the influence of magnetic field topology on plasma evolution in pulsed power driven plasmas. The experimental program involved intense field-matter interaction in the generation of the proton probe, as well as the generation of plasma subjected to 1 MegaGauss scale magnetic fields. The computational aspect included two well-documented codes, in combination for the first time to provide accurate interpretation of the experimental results. The broader impact included the support of 2 graduate students, one at UCSD and one at NTF, who were exposed to both the experimental physics work, the MHD and PIC modeling of the system. A first generation college undergraduate student was employed to assist in experiments and data analysis throughout the project. Data resulting from the research program were broadly disseminated by publication in scientific journals, and presentation at international and national conferences and workshops.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Final Technical Report: The Water-to-Wire (W2W) Project

The purpose of the Free Flow Power (FFP) Water-to-Wire Project (Project) was to evaluate and optimize the performance, environmental compatibility, and cost factors of FFP hydrokinetic turbines through design analyses and deployments in test flumes and riverine locations.

13 HYDRO ENERGY↗
DOE OSTI2015

Non-thermal x-ray emission from wire array z-pinches

We report on experiments demonstrating the transition from thermally-dominated K-shell line emission to non-thermal, hot-electron-driven inner-shell emission for z pinch plasmas on the Z machine. While x-ray yields from thermal K-shell emission decrease rapidly with increasing atomic number Z, we find that non-thermal emission persists with favorable Z scaling, dominating over thermal emission for Z=42 and higher (hn ≥ 17keV). Initial experiments with Mo (Z=42) and Ag (Z=47) have produced kJ-level emission in the 17-keV and 22-keV Kα lines respectively. We will discuss the electron beam properties that could excite these non - thermal lines. We also report on experiments that have attempted to control non - thermal K - shell line emission by modifying the wire array or load hardware setup.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2016

Design and fabrication of a 30 T superconducting solenoid using overpressure processed Bi2212 round wire

High field superconducting magnets are used in particle colliders, fusion energy devices, and spectrometers for medical imaging and advanced materials research. Magnets capable of generating fields of 20-30 T are needed by future accelerator facilities. A 20-30 T magnet will require the use of high-temperature superconductors (HTS) and therefore the challenges of high field HTS magnet development need to be addressed. Superconducting Bi 2 Sr 2 CaCu 2 O x (Bi2212) conductors fabricated by the oxide-powder-in-tube (OPIT) technique have demonstrated the capability to carry large critical current density of 10 5 A/cm 2 at 4.2 K and in magnetic fields up to 45 T. Available in round wire multi-filamentary form, Bi2212 may allow fabrication of 20-50 T superconducting magnets. Until recently the performance of Bi2212 has been limited by challenges in realizing high current densities (J c ) in long lengths. This problem now is solved by the National High Magnetic Field Lab using an overpressure (OP) processing technique, which uses external pressure to process the conductor. OP processing also helps remove the ceramic leakage that results when Bi-2212 liquid leaks out from the sheath material and reacts with insulation, coil forms, and flanges. Significant advances have also been achieved in developing novel insulation materials (TiO 2 coating) and Ag-Al sheath materials that have higher mechanical strengths than Ag-0.2wt.% Mg, developing heat treatment approaches to broadening the maximum process temperature window, and developing high-strength, mechanical reinforced Bi-2212 cables. In the Phase I work, we leveraged these new opportunities to prototype overpressure processed solenoids and test them in background fields of up to 14 T. Additionally a design of a fully superconducting 30 T solenoid was produced. This work in conjunction with the future path outlined in the Phase II proposal would provide a major step toward qualifying Bi2212 technology for use in high-field accelerator magnets. Additionally, the performance parameters match key requirements of a final muon beam cooling solenoid. This technology will also be of interest to high-field NMR manufacturers.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

High Efficient RING-Cavity Laser Wire Scanner for Intense CW Electron Beams

There is currently a lack of diagnostics for measuring transverse beam size high intensity electron beams which have very different dynamics when compared to less intense beams. To address this deficiency in beam diagnostic technology, we are developing a "laser wire scanner" in which a high-intensity laser pulse is scattered from the electron beam, production of a pulse of hard x-rays. By scanning this laser pulse across the electron bunch and measuring the x-ray signal we can reconstruct the electron beam size.

O'Shea, Finn↗
DOE OSTI2018

An Uncertainty Quantification of the Computational Fluid Dynamics Solution to the Modeling of the Contact Point in a Wire-Wrapped Fuel Assembly

An uncertainty quantification and sensitivity analysis of the turbulent flow in a wire-wrapped pin bundle to the contact-point model and the inlet conditions is presented. Three geometries are considered in this work that are an infinitely large bundle (single subchannel with periodic boundary conditions in the stream-wisedirection), a 7-pin bundle and a 19-pin bundle. The response functions of this study are the friction factor, thevorticity and the mixing parameters. The results show that the friction factor is not sensitive to the contact-point model. The vorticity shows a strong dependency to the inclusion of prismatic layers near the wall boundaries. Results for the mixing parameters are inconclusive. A variance-based sensitivity analysis(Sobol indices) indicates that the influence of the contact-point model on the variance of the friction factor decreases when increasing the size of the bundle. Other response functions (vorticity and mixing parameters)show little sensitivity to the size of the bundle.

42 ENGINEERING↗