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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 1,045 records · Page 58
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

LOCAL INTERSTELLAR MEDIUM: SIX YEARS OF DIRECT SAMPLING BY IBEX

The Interstellar Boundary Explorer (IBEX) has been directly observing neutral atoms from the local interstellar medium for the last six years (2009–2014). This paper ties together the 14 studies in this Astrophysical Journal Supplement Series Special Issue, which collectively describe the IBEX interstellar neutral results from this epoch and provide a number of other relevant theoretical and observational results. Interstellar neutrals interact with each other and with the ionized portion of the interstellar population in the “pristine” interstellar medium ahead of the heliosphere. Then, in the heliosphere's close vicinity, the interstellar medium begins to interact with escaping heliospheric neutrals. In this study, we compare the results from two major analysis approaches led by IBEX groups in New Hampshire and Warsaw. We also directly address the question of the distance upstream to the pristine interstellar medium and adjust both sets of results to a common distance of ∼1000 AU. The two analysis approaches are quite different, but yield fully consistent measurements of the interstellar He flow properties, further validating our findings. While detailed error bars are given for both approaches, we recommend that for most purposes, the community use “working values” of ∼25.4 km s{sup −1}, ∼75.°7 ecliptic inflow longitude, ∼ −5.°1 ecliptic inflow latitude, and ∼7500 K temperature at ∼1000 AU upstream. Finally, we briefly address future opportunities for even better interstellar neutral observations to be provided by the Interstellar Mapping and Acceleration Probe mission, which was recommended as the next major Heliophysics mission by the NRC's 2013 Decadal Survey.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

OpenFAST Modeling of the T-Omega Wind Floating Offshore Wind Turbine System

To reduce the cost of offshore wind energy through a more efficient design of the floating support structure, T-Omega Wind developed a novel lightweight and shallow-draft platform concept that aims to achieve a wave-following behavior without resonance amplification. The rotor and generator are carried by four tower legs with each leg supported by a shallow-draft float at the base. In preparation for a more detailed analysis, a coupled aero-hydro-elastic model of the proposed concept is developed in OpenFAST. The detailed modeling approach is presented, including a novel application of the SubDyn substructure dynamics module of OpenFAST to approximate the loads on the axle tube at the tower top from the rotor hub bearings. Preliminary results obtained with the OpenFAST model by rigidifying the substructure and blades indicate that the original sizing of the design can lead to large hub acceleration in the axial/surge and pitch directions due to platform-pitch motion. The high axial acceleration also potentially leads to large bending moments in the four tower legs. To address these issues, an updated design is developed with, among other changes, increased float spacing at the tower base and improved shear-transmitting geometry of the tower legs. The new design suggests significantly reduced extreme hub accelerations under the same conditions even with structural flexibility and will be further analyzed in the future through full aero-hydro-servo-elastic simulations.

FOWT↗
DOE OSTI2022

Construction and characterization of a genome-scale ordered mutant collection of Bacteroides thetaiotaomicron

Ordered transposon-insertion collections, in which specific transposon-insertion mutants are stored as monocultures in a genome-scale collection, represent a promising tool for genetic dissection of human gut microbiota members. However, publicly available collections are scarce and the construction methodology remains in early stages of development. Here, we describe the assembly of a genome-scale ordered collection of transposon-insertion mutants in the model gut anaerobe Bacteroides thetaiotaomicron VPI-5482 that we created as a resource for the research community. We used flow cytometry to sort single cells from a pooled library, located mutants within this initial progenitor collection by applying a pooling strategy with barcode sequencing, and re-arrayed specific mutants to create a condensed collection with single-insertion strains covering >2500 genes. To demonstrate the potential of the condensed collection for phenotypic screening, we analyzed growth dynamics and cell morphology. We identified both growth defects and altered cell shape in mutants disrupting sphingolipid synthesis and thiamine scavenging. Finally, we analyzed the process of assembling the B. theta condensed collection to identify inefficiencies that limited coverage. We demonstrate as part of this analysis that the process of assembling an ordered collection can be accurately modeled using barcode sequencing data. We expect that utilization of this ordered collection will accelerate research into B. theta physiology and that lessons learned while assembling the collection will inform future efforts to assemble ordered mutant collections for an increasing number of gut microbiota members.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Efficient Coupling of Monte-Carlo Neutral and Fluid Plasma Models

The objective of this project was to develop an efficient scheme to couple kinetic Monte-Carlo (MC) neutral-species and fluid plasma-(charged-) species codes for the simulation of transport in the outer edge region of magnetic fusion energy (MFE) edge simulation. There was a need for improvement over existing plasma-neutral transport codes, which are either all-fluid, and insufficiently accurate in some important regimes, or very slow due to their use of simple explicit (operator-split) coupling.The resulting capability will be of great value in the interpretation and design of present-day and future MFE plasma devices (e.g., ITER). We developed and demonstrated several new algorithms that can greatly accelerate coupling between numerical code/model compon ents where the coupling introduces numerical “stiffness” and where there is a Monte-Carlo component.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

LLE-Annual report input

In FY18, an LLNL/GA/Michigan University team carried out the project “Exploring pair plasmas and their applications” with 2 LBS shot days on OMEGA EP. The campaign used an EP short pulse beam to produce jets of electron-positron antimatter pairs while the 2nd short pulse beam was used to producing protons to diagnose the laser-target interactions. The experiments focused on 1) inhensing the pair yield using nano-structure targets and 2) collimating/focusing positron jets through curved sheath potential from shaped target surface. The experiments successfully demonstrated both the yield enhensement and the positron focusing. The data provided basis futrue experiments on labortary astrophysics using the pair jet – plasma interaction to drive beam instabilities. A total of 14 shots were performed in the fiscal year. The EP short pulse beams (~1 kJ in 10 ps) irradiated targets of 1 mm thick Au targets, with and without the nano-structure on the laser interaction surface. It was found that for the same laser energy, positron yields and acceleration both were increased dramatically by using nano-structure. This finding is important to the future experiments and applications using laser pair jets. Previous experiments used gold targets almost exclusively. It was also found that a hemispherical shaped backsurface can focuing the positron jets through the sheath field – like that observed in proton focusing. This observation is important as it demonstrated that higher pair density can be achieved by reducing their volume, which may enable the development of instablities predicted by theory. The prior experiments showed that quasi-monoenergetic relativistic positron jets are formed during high-intensity irradiation of thick gold targets, and that these jets can be strongly collimated using the magnetized-inertial fusion electrical delivery system (MIFEDS). The external field produces a 40-fold increase in the peak positron and electron signal [4]. The positron yield was found to scale as the square of the laser energy. The FY15 results revealed another dimension of scaling on the target materials. The favorable scaling would enable the laboratory study of relativistic pair plasmas that are important to understanding some of the most exotic and energetic systems in the universe.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Thermal-Hydraulics Modeling and Simulations of Hot Pool Using the SAS-CFD Coupled Code

The main goal of this activity is to test the dynamic coupling of the SAS4A/SASSYS-1 (SAS) and CFD models, using a recently patched version of the SAS code intended to address an undocumented limitation that hindered the Versatile Test Reactor (VTR) simulation efforts in FY21. As described in previous VTR calculation reports, the undocumented limitation in SAS v5.4 does not allow the user to activate the CFD coupling option during restart calculations. Since the analysts were unaware of this limitation, prior SAS-CFD simulation results for the protected station blackout (PSBO) transient were erroneous. Root-cause analysis was performed to determine the cause of this undocumented limitation in SAS v5.4, the SAS software was updated in a new patch, and the SAS-CFD simulations were repeated with this patched software. The results of the SAS-CFD simulations documented in this report show that the software patch does address the cited issue, and that the patched software indeed supports the activation of the CFD coupling model in restart calculations. The SAS development team will determine the schedule for implementing the patch in an official software release. This report documents updated SAS-CFD simulations of the PSBO transient response in the VTR. The hot pool is modeled with the CFD code STAR-CCM+, which is coupled at the flow boundaries to the SAS model of the primary heat transport system. SAS computes the mass flow rate and temperature at each core subassembly outlet, the thermal insulation cavity bypass, and the IHX inlet windows. CFD in turn computes the absolute pressure and temperature at each of these boundaries. The SAS code will ignore the temperature data at flow boundaries where flow is directed into the hot pool, i.e., at the core subassembly outlets unless flow reversal occurs. Similarly, CFD will ignore temperature data at boundaries where the flow is directed out of the hot pool, i.e., at the IHX inlets except under flow reversal. The focus of this work is to ensure that the SAS software patch addresses the undocumented limitation described in prior VTR calculation reports, rather than the accurate assessment of thermal stratification in the VTR during protected transients. This motivates the development of a new, simplified CFD model with a coarser mesh to accelerate the testing process. The updated model, and simplifying assumptions, are documented in this report. In future work, the thermal stratification assessment should be performed in more detail. The simplified CFD model can be improved by performing grid convergence studies sensitivity studies of turbulence parameters (e.g., Prandtl number, turbulence production and dissipation parameters) on temperature distributions and thermal stratification.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2026

Commissioning of the IOTA Proton Injector

The IOTA Proton Injector (IPI) at the Fermilab Accelerator Science and Technology facility (FAST) is a machine capable of delivering up to 14 mA pulses of protons at 2.5 MeV to the Integrable Optics Test Accelerator (IOTA) ring. Its construction was completed in the fall of 2025, followed by a successful commissioning run scheduled to conclude at the end of May 2026. It operates alongside the existing electron injector beamline to facilitate further beam physics research and continued development of novel accelerator technologies at the IOTA ring. This report details the current operational profile, known challenges, and future plans for the proton program development at FAST.

Romanov, A. [Fermilab] (ORCID:0000000287065709)↗
NASA NTRS1982

Photothermal characterization of encapsulant materials for photovoltaic modules

A photothermal test matrix and a low cost testing apparatus for encapsulant materials of photovoltaic modules were defined. Photothermal studies were conducted to screen and rank existing as well as future encapsulant candidate materials and/or material formulations in terms of their long term physiochemical stability under accelerated photothermal aging conditions. Photothermal characterization of six candidate pottant materials and six candidate outer cover materials were carried out. Principal products of photothermal degradation are identified. Certain critical properties are also monitored as a function of photothermal aging.

Liang, R. H.↗
NASA NTRS1984

Electromagnetic thrusters for spacecraft prime propulsion

The benefits of electromagnetic propulsion systems for the next generation of US spacecraft are discussed. Attention is given to magnetoplasmadynamic (MPD) and arc jet thrusters, which form a subset of a larger group of electromagnetic propulsion systems including pulsed plasma thrusters, Hall accelerators, and electromagnetic launchers. Mission/system study results acquired over the last twenty years suggest that for future prime propulsion applications high-power self-field MPD thrusters and low-power arc jets have the greatest potential of all electromagnetic thruster systems. Some of the benefits they are expected to provide include major reductions in required launch mass compared to chemical propulsion systems (particularly in geostationary orbit transfer) and lower life-cycle costs (almost 50 percent less). Detailed schematic drawings are provided which describe some possible configurations for the various systems.

Rudolph, L. K.↗
NASA NTRS1989

Correlation between X-ray flux and rotational acceleration in Vela X-1

The results of a search for correlations between X-ray flux and angular acceleration for the accreting binary pulsar Vela X-1 are presented. Results are based on data obtained with the Hakucho satellite during the interval 1982 to 1984. In undertaking this correlation analysis, it was necessary to modify the usual statistical method to deal with conditions imposed by generally unavoidable satellite observing constraints, most notably a mismatch in sampling between the two variables. The results are suggestive of a correlation between flux and the absolute value of the angular acceleration, at a significance level of 96 percent. The implications of the methods and results for future observations and analysis are discussed.

Deeter, J. E.↗
NASA NTRS1988

Gamma-ray detectors (greater than 10 MeV)

Photons in the energy region above 10 MeV can provide unique information about the highest energy particles produced in solar flares. Measurements of the energy spectra, temporal behavior and anisotropies of the incident photons, can give valuable insights into the particle acceleration process. The detection techniques used at these energies, typical instruments which use these techniques, and future solar missions are reviewed.

Owens, Alan↗
NASA NTRS1989

Free electron lasers driven by linear induction accelerators: High power radiation sources

The technology of Free Electron Lasers (FELs) and linear induction accelerators (LIAs) is addressed by outlining the following topics: fundamentals of FELs; basic concepts of linear induction accelerators; the Electron Laser Facility (a microwave FEL); PALADIN (an infrared FEL); magnetic switching; IMP; and future directions (relativistic klystrons). This presentation is represented by viewgraphs only.

Orzechowski, T. J.↗
NASA NTRS1989

The composition of cosmic rays at high energies

Measurements of the composition of the cosmic rays at high energies, and of the energy spectra of the individual components provide the basis for the understanding of the sources, of the acceleration mechanism, and of the galactic containment of these particles. A brief review of the presently available information and a recent measurement performed on the Space Shuttle to substantially extend the range of energies in which the elemental composition is known are described. Results, and recent data on the electron component of cosmic rays are discussed and summarized. The body of data now available contains several features that are difficult to explain within current models of galactic shock acceleration and 'leakly box' containment. The need for further measurements is emphasized and possible opportunities for future work are briefly discussed.

Muller, Dietrich↗
NASA NTRS1999

Demonstrating the Performance Benefits of the Strutjet RBCC for Space Launch Architectures

The Rocket Based Combined Cycle (RBCC) engine synergistically combines the best elements of airbreathing and rocket propulsion to benefit a wide range of future reusable launch vehicles (RLV). Aerojet's Strutjet RBCC offers high Isp during mid-phase acceleration, and high thrust for boost and final ascent phases. The result is a relatively low gross weight vehicle that reduces thrust requirements compared with all-rocket solutions. Relative to combination propulsion systems, the integrated propulsive elements of the Strutjet reduce engine weight and complexity. This paper will summarize the results of tests demonstrating our latest hydrogen-fueled Strutjet RBCC engine performance, including inlet operability and performance over a range of conditions, sea level static and Mach 2.4 rocket thrust augmentation, ramjet and scramjet performance, combined scramjet/rocket performance at Mach 8, and ascent mode rocket performance. These tests have significantly advanced the technology readiness of the Strutjet engine and substantiate the performance benefits of RBCC engines for reusable launch vehicle applications. A companion paper provides a focus on Strutjet as a basis for advanced air and space architecture, covering hydrogen and hydrocarbon fuels and cooled structures.

Siebenhaar, Adam↗
NASA NTRS2014

Time-Dependent Behavior of High-Strength Kevlar and Vectran Webbing

High-strength Kevlar and Vectran webbings are currently being used by both NASA and industry as the primary load-bearing structure in inflatable space habitation modules. The time-dependent behavior of high-strength webbing architectures is a vital area of research that is providing critical material data to guide a more robust design process for this class of structures. This paper details the results of a series of time-dependent tests on 1-inch wide webbing including an initial set of comparative tests between specimens that underwent realtime and accelerated creep at 65 and 70% of their ultimate tensile strength. Variability in the ultimate tensile strength of the webbings is investigated and compared with variability in the creep life response. Additional testing studied the effects of load and displacement rate, specimen length and the time-dependent effects of preconditioning the webbings. The creep test facilities, instrumentation and test procedures are also detailed. The accelerated creep tests display consistently longer times to failure than their real-time counterparts; however, several factors were identified that may contribute to the observed disparity. Test setup and instrumentation, grip type, loading scheme, thermal environment and accelerated test postprocessing along with material variability are among these factors. Their effects are discussed and future work is detailed for the exploration and elimination of some of these factors in order to achieve a higher fidelity comparison.

Jones, Thomas C.↗
NASA NTRS2020

Urban Air Mobility (UAM) Working Groups

The NASA Aeronautics Research Mission Directorate (ARMD) is bringing together public, private, and academic organizations to collaborate with NASA in Urban Air Mobility (UAM) working groups. The primary purpose of the working groups is to accelerate the development of safe, high-volume UAM flight operations in the existing and anticipated future national airspace system. In coordination with the Grand Challenge series, industry developments and other ARMD efforts, these working groups will contribute to the enablement of UAM markets. Working group activities will seek to align the community on concepts to enable UAM, including communicating industry demonstrations and R&D priorities. The collaborative efforts will facilitate the identification of critical parameters and standards necessary to develop the framework and approach for safety, certification, airspace, aircraft concepts, technologies, and architectures. The realization of the UAM vision will be possible only though the efforts and contributions of multiple stakeholders, each possessing the necessary authority, expertise, and/or resources to fulfill a critical role in UAM's development, approval, and implementation. The applicable participants will become integral to the UAM working groups and will provide a platform for those stakeholders to collaborate and impact the overall ecosystem.

Kopardekar, Parimal H.↗
NASA NTRSDate not supplied

HyTEC Hybrid Thermally Efficient Core

As part of the NASA Advanced Air Vehicles Program (AAVP), a new project is being formulated called Hybrid Thermally Efficient Core (HyTEC) in which NASA intends to accelerate the development of small turbofan engine core technologies, culminating in an advanced core demonstration in the 2026 timeframe. NASA Glenn Research Center plans to issue a NASA Research Announcement (NRA) for HyTEC Small Core Technology Demonstration, in preparation the HyTEC Project is holding an industry day February 24, 2021. The HyTEC goal is to demonstrate increased thermal efficiency with integrated high power-density core engine technologies achieving a 5- to 10-percent fuel burn benefit, versus 2020 best in class, for early 2030s entry into service (EIS) single-aisle aircraft. In order to accomplish this, NASA intends to collaborate with industry in a cost sharing arrangement on key technologies that NASA can accelerate to strengthen the US industry position on highly efficient, power dense small cores for a future single aisle aircraft.

Anthony Nerone↗
NASA NTRS2023

Performance Modeling of Urban Air Mobility Vehicles to Support Air Traffic Management Research

The recent emergence of Urban Air Mobility (UAM) vehicles has resulted in a need for flight performance models that enable comprehensive simulation-based research on air traffic management topics such as route structure, scheduling, and separation standards. Successful performance modeling methods exist for a wide range of traditional aircraft designs. However, comparable modeling methods appropriate for UAM vehicles that combine fixed-wing and rotorcraft performance have not yet been established. One challenge to progress has been the lack of available data capturing the performance characteristics and unique flight profiles of these aircraft. This paper describes methods used to generate the required performance data and the development of performance models for UAM vehicles. Included is a review of the energy and power equations often used in developing performance models for traditional aircraft as well as a discussion of their applicability to UAM vehicles. The challenge of generating realistic performance data in over-actuated vehicles transitioning from hover to cruise flight is also addressed through an approach based on objective function optimization. A table-based performance model format adapted to UAM configurations is described, as well as parametric models intended to accompany the performance table to allow detailed modeling of power and fuel consumption during accelerated flight, turning flight, or flight at an arbitrary climb or descent rate. A discussion of future work is also provided, including the need for refinement of UAM performance modeling methods and formats, especially in conjunction with improvements to aerodynamic modeling of vehicles with complex designs where strong interaction effects may dominate important regions of the flight envelope.

Performance Modeling↗