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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 1,765 records · Page 98
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Validation of Pronghorn’s Subchannel code using the EBR-II shutdown heat removal tests

A Subchannel application (Pronghorn-SC) is developed in MOOSE, which affords the required flow field resolution, while still preserving an engineering-scale approach. This new solver can be natively coupled to Pronghorn and other MOOSE objects to enable full-core, multi-physics, multi-scale engineering studies. This work utilizes the EBR-II SHRT tests to validate the subchannel capabilities. Multi-scale and multi-physics coupling is used to improve the fidelity of the subchannel code calculations.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
NASA NTRS1989

Comparison of propeller cruise noise data taken in the NASA Lewis 8- by 6-foot wind tunnel with other tunnel and flight data

The noise of advanced high speed propeller models measured in the NASA 8- by 6-foot wind tunnel has been compared with model propeller noise measured in another tunnel and with full-scale propeller noise measured in flight. Good agreement was obtained for the noise of a model counterrotation propeller tested in the 8- by 6-foot wind tunnel and in the acoustically treated test section of the Boeing Transonic Wind Tunnel. This good agreement indicates the relative validity of taking cruise noise data on a plate in the 8- by 6-foot wind tunnel compared with the free-field method in the Boeing tunnel. Good agreement was also obtained for both single rotation and counter-rotation model noise comparisons with full-scale propeller noise in flight. The good scale model to full-scale comparisons indicate both the validity of the 8- by 6-foot wind tunnel data and the ability to scale to full size. Boundary layer refraction on the plate provides a limitation to the measurement of forward arc noise in the 8- by 6-foot wind tunnel at the higher harmonics of the blade passing tone. The use of a validated boundary layer refraction model to adjust the data could remove this limitation.

Dittmar, James H.↗
NASA NTRS1989

Comparison of propeller cruise noise data taken in the NASA Lewis 8- by 6-foot wind tunnel with other tunnel and flight data

The noise of advanced high speed propeller models measured in the NASA 8- by 6-foot wind tunnel has been compared with model propeller noise measured in another tunnel and with full-scale propeller noise measured in flight. Good agreement was obtained for the noise of a model counterrotation propeller tested in the 8- by 6-foot wind tunnel and in the acoustically treated test section of the Boeing Transonic Wind Tunnel. This good agreement indicates the relative validity of taking cruise noise data on a plate in the 8- by 6-foot wind tunnel compared with the free-field method in the Boeing tunnel. Good agreement was also obtained for both single rotation and counter-rotation model noise comparisons with full-scale propeller noise in flight. The good scale model to full-scale comparisons indicate both the validity of the 8- by 6-foot wind tunnel data and the ability to scale to full size. Boundary layer refraction on the plate provides a limitation to the measurement of forward arc noise in the 8- by 6-foot wind tunnel at the higher harmonics of the blade passing tone. The sue of a validated boundary layer refraction model to adjust the data could remove this limitation.

Dittmar, James↗
NASA NTRS1991

Turbomachinery noise

Summarized here are key advances in experimental techniques and theoretical applications which point the way to a broad understanding and control of turbomachinery noise. On the experimental side, the development of effective inflow control techniques makes it possible to conduct, in ground based facilities, definitive experiments in internally controlled blade row interactions. Results can now be valid indicators of flight behavior and can provide a firm base for comparison with analytical results. Inflow control coupled with detailed diagnostic tools such as blade pressure measurements can be used to uncover the more subtle mechanisms such as rotor strut interaction, which can set tone levels for some engine configurations. Initial mappings of rotor wake-vortex flow fields have provided a data base for a first generation semiempirical flow disturbance model. Laser velocimetry offers a nonintrusive method for validating and improving the model. Digital data systems and signal processing algorithms are bringing mode measurement closer to a working tool that can be frequently applied to a real machine such as a turbofan engine. On the analytical side, models of most of the links in the chain from turbomachine blade source to far field observation point have been formulated. Three dimensional lifting surface theory for blade rows, including source noncompactness and cascade effects, blade row transmission models incorporating mode and frequency scattering, and modal radiation calculations, including hybrid numerical-analytical approaches, are tools which await further application.

Groeneweg, John F.↗
NASA NTRS2022

Estimation of Fire-induced CO Plume Age from NAST-I During the FIREX-AQ Field Campaign

Ultra-spectrally resolved infrared measurements from aircraft and space-based observations contain information about tropospheric carbon monoxide (CO) and ozone (O3), as well as other trace species. A methodology for retrieving these tropospheric trace species from such remotely sensed spectral data has been developed and validated for the National Airborne Sounder Testbed-Interferometer (NAST–I). The Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) field campaign was conducted during August 2019 to investigate the impact of wildfire and biomass smoke on air quality and weather in the continental United States. NAST–I CO and O3 measurements from the recent FIREX-AQ field campaign are presented and used to estimate wildfire plume age. Results show enhanced levels of CO in the evolving plume as it is transported away from the fire ground site, and its plume age is associated with the plume distance in both the vertical and horizontal directions from the wildfire location. These results are enabled by the moderate-vertical and high-horizontal resolution obtained from the NAST–I IR spectrometer onboard the NASA ER-2 aircraft. This study advances our knowledge of fire-induced plumes with their evolution and age characterized in three-dimensional space using information from NAST–I retrieved CO and O3 and relative changes in their concentrations.

plume age↗
DOE OSTI2020

Characterization of Self-Magnetic Pinch (SMP) Radiographic Diode Performance on RITS-6 at Sandia National Laboratories

The goals of an electron beam-driven radiographic source are the focusing of high current at high voltage to a minimal spot size with excellent shot-to-shot reproducibility. The Self-Magnetic Pinch (SMP) diode makes use of such an intense electron beam impinging on a high-atomic weight (tantalum) converter, a counter-streaming ion beam to help minimize the spot size, and operation in a magnetic field-free diode region which further encourages small spot size. Through a series of diode development experiments, output voltages up to 12.5 MV and output currents up to 225 kA have been characterized, with resulting spot sizes below ~ few mm. Scaling studies with parameter variation, such as diode aspect ratio and anode-cathode (A-K) gap variation, give systematic validation to what has heretofore been noted anecdotally by other research groups. While the lack of an imbedded magnetic field helps minimize the SMP spot size, a secondary result may be the generation of beam instabilities which can terminate the radiation pulse. There is anecdotal evidence that in-situ DC heating of the diode region can help stabilize the beam pinch. Clear experimental evidence exists that DC heating/RF cleaning results in better control over the counter-streaming ion population. Expanded use of spatial dose-rate detection is shown to yield new insights into electron beam dynamics in the SMP diode. An attendant study of the SMP diode as a load for an Inductive Voltage Adder (IVA) driver leads to insights into the behavior of the IVA-SMP diode configuration, viewed as a total system, and yields constraints on the overall impedance behavior of the SMP diode load.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS2000

SeaWiFS Postlaunch Calibration and Validation Analyses

The effort to resolve data quality issues and improve on the initial data evaluation methodologies of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project was an extensive one. These evaluations have resulted, to date, in three major reprocessings of the entire data set where each reprocessing addressed the data quality issues that could be identified up to the time of each reprocessing. The number of chapters (21) needed to document this extensive work in the SeaWiFS Postlaunch Technical Report Series requires three volumes. The chapters in Volumes 9, 10, and 11 are in a logical order sequencing through sensor calibration, atmospheric correction, masks and flags, product evaluations, and bio-optical algorithms. The first chapter of Volume 9 is an overview of the calibration and validation program, including a table of activities from the inception of the SeaWiFS Project. Chapter 2 describes the fine adjustments of sensor detector knee radiances, i.e., radiance levels where three of the four detectors in each SeaWiFS band saturate. Chapters 3 and 4 describe the analyses of the lunar and solar calibration time series, respectively, which are used to track the temporal changes in radiometric sensitivity in each band. Chapter 5 outlines the procedure used to adjust band 7 relative to band 8 to derive reasonable aerosol radiances in band 7 as compared to those in band 8 in the vicinity of Lanai, Hawaii, the vicarious calibration site. Chapter 6 presents the procedure used to estimate the vicarious calibration gain adjustment factors for bands 1-6 using the waterleaving radiances from the Marine Optical Buoy (MOBY) offshore of Lanai. Chapter 7 provides the adjustments to the coccolithophore flag algorithm which were required for improved performance over the prelaunch version. Chapter 8 is an overview of the numerous modifications to the atmospheric correction algorithm that have been implemented. Chapter 9 describes the methodology used to remove artifacts of sun glint contamination for portions of the imagery outside the sun glint mask. Finally, Chapter 10 explains a modification to the ozone interpolation method to account for actual time differences between the SeaWiFS and Total Ozone Mapping Spectrometer (TOMS) orbits.

Hooker, Stanford B.↗
NASA NTRS1994

Evaluation of a GCM cirrus parameterization using satellite observations

This study applies a simple yet effective methodology to validate a general circulation model parameterization of cirrus ice water path. The methodology combines large-scale dynamic and thermodynamic fields from operational analyses with prescribed occurrence of cirrus clouds from satellite observations to simulate a global distribution of ice water path. The predicted cloud properties are then compared with the corresponding satellite measurements of visible optical depth and infrared cloud emissivity to evaluate the reliability of the parameterization. This methodology enables the validation to focus strictly on the water loading side of the parameterization by eliminating uncertainties involved in predicting the occurrence of cirrus internally within the parameterization. Overall the parameterization performs remarkably well in capturing the observed spatial patterns of cirrus optical properties. Spatial correlations between the observed and the predicted optical depths are typically greater than 0.7 for the tropics and northern hemisphere midlatitudes. The good spatial agreement largely stems from the strong dependence of the ice water path upon the temperature of the environment in which the clouds form. Poorer correlations (r approximately 0.3) are noted over the southern hemisphere midlatitudes, suggesting that additional processes not accounted for by the parameterization may be important there. Quantitative evaluation of the parameterization is hindered by the present uncertainty in the size distribution of cirrus ice particles. Consequently, it is difficult to determine if discrepancies between the observed and the predicted optical properties are attributable to errors in the parameterized ice water path or to geographic variations in effective radii.

Soden, B. J.↗
DOE OSTI2026

Theoretical model of dielectrophoretic water vapor condensation during multiphase flow of electrically charged water droplets in air

Water droplet growth in air, influenced by vapor diffusion and electrical charging, has significant implications for indoor air quality, cloud formation, and aerosol dynamics. Here, this study presents a comprehensive theoretical model that describes the growth dynamics of electrically charged water droplets under external electric fields, incorporating diffusion, electrostatic, and dielectrophoretic forces to enhance understanding and practical applications in air dehumidification and environmental control. A theoretical model was established to analyze the growth dynamics of the charged water droplets. The approach extended the thermodynamic framework of the Modified Kelvin-Thomson equation by integrating electrostatic and dielectrophoretic effects, enabling a comprehensive evaluation of vapor concentration near the surface of charged droplets. A sensitivity analysis was performed to assess the roles of droplet size, electric field intensity, surface charge, and vapor concentration on condensation rates. The study progressed beyond the classical diffusion-limited growth of neutral droplets, addressing the behavior of charged droplets in electrohydrodynamic environments. The model highlighted the significance of dielectrophoretic drift flux for dipolar vapor molecules, especially in micron-sized droplets ranging from 10 to 100 µm. Findings demonstrated that, for smaller droplets subjected to elevated electrical charge, average growth rates varied from 0.3 to 1.6 µm/s if the air relative humidity increased from 50 to 100 %. Analytical results are corroborated by numerical simulations, which exhibited strong concordance, thereby validating the proposed theoretical approach. This research introduced an innovative and scalable analytical methodology for electric field-enhanced droplet growth, offering valuable insights into the advancement of energy-efficient air dehumidification, water desalination, and atmospheric water harvesting technologies.

42 ENGINEERING↗
DOE OSTI2025

Towards modelling AR Sco: calibration – reproducing high-energy pulsar emission and testing convergence to Aristotelian electrodynamics

In recent years, kinetic simulations have been crucial to further our understanding of pulsar electrodynamics. Yet, due to the large-scale separation between the gyro-period and the stellar rotation period, resolving the particle gyration has been computationally unfeasible for realistic pulsar parameters. The main aim of this work is comparing our gyro-phase-resolved model with a gyro-centric pulsar model, where our model solves the general equations of motion with included radiation reaction using a higher order numerical solver with adaptive time-steps. Specifically, we aim to (i) reproduce a pulsar’s high-energy emission maps, namely one with 10 per cent of the surface B-field strength of Vela, and the spectra produced by an independent gyro-centric pulsar emission model; and (ii) test convergence of these results to the radiation-reaction limit of Aristotelian electrodynamics. (iii) Additionally, we identify the effect that a large $E_{\parallel }$-field has on the trajectories and radiation calculations. We find that we can reproduce the curvature radiation emission maps and spectra well, using 10 per cent field strengths of the Vela pulsar and injecting our particles at a higher altitude in the magnetosphere. Using sufficiently large $E_{\parallel }$-fields, our numeric results converge to the analytic radiation-reaction limit trajectories. Additionally, we illustrate the importance of accounting for the $\mathbf {E}\times \mathbf {B}$-drift in the particle trajectories and radiation calculations, validating the Harding and collaborators’ model approach. Lastly, we found that our model deals very well with the high-radiation-reaction and high-field regimes present in pulsars.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2012

Implementing the Mars Science Laboratory Terminal Descent Sensor Field Test Campaign

The Mars Science Laboratory (MSL) will deliver a 900 kg rover to the surface of Mars in August 2012. MSL will utilize a new pulse-Doppler landing radar, the Terminal Descent Sensor (TDS). The TDS employs six narrow-beam antennas to provide unprecedented slant range and velocity performance at Mars to enable soft touchdown of the MSL rover using a unique sky crane Entry, De-scent, and Landing (EDL) technique. Prior to use on MSL, the TDS was put through a rigorous verification and validation (V&V) process. A key element of this V&V was operating the TDS over a series of field tests, using flight-like profiles expected during the descent and landing of MSL over Mars-like terrain on Earth. Limits of TDS performance were characterized with additional testing meant to stress operational modes outside of the expected EDL flight profiles. The flight envelope over which the TDS must operate on Mars encompasses such a large range of altitudes and velocities that a variety of venues were neces-sary to cover the test space. These venues included an F/A-18 high performance aircraft, a Eurocopter AS350 AStar helicopter and 100-meter tall Echo Towers at the China Lake Naval Air Warfare Center. Testing was carried out over a five year period from July 2006 to June 2011. TDS performance was shown, in gen-eral, to be excellent over all venues. This paper describes the planning, design, and implementation of the field test campaign plus results and lessons learned.

Mars Science Laboratory (MSL)↗
NASA NTRS1992

A status of the activities of the NASA/MSFC pump stage technology team

The Consortium for Computational Fluid Dynamics (CFD) Application in Propulsion Technology was established to aid the transfer of CFD related advancements among academia, government agencies, and industry. The specific goals of the Consortium are to develop CFD methodologies necessary to solve propulsion problems, to validate these methodologies, and to apply these methodologies in the design process. To accomplish these goals, a team of experts in various related fields was formed, a schedule of activities necessary to meet the goals was generated, and funding for the activities was obtained from NASA. During the past year (Mar. 1991 - Mar. 1992) the team's activities have focused on preliminary code validation and on the design of an advanced impeller. Six codes were used to calculate the flow in a Rocketdyne 0.3 flow coefficient inducer, and the results were compared to L2F data available for the inducer. This activity identified shortcomings in the experimental data sets and in the analytical solutions which must be surmounted in any future team activity. The design of the advanced impeller relied heavily on CFD results to obtain an optimized geometry. The optimized geometry was analyzed using four different codes, at design and off-design conditions. Activities for the next year include the optimization of a tandem blade impeller design, benchmark of CFD codes for diffuser and volute flows, the collection of L2F data for 'state-of-the-art' impeller and inducer, and the verification of the advanced pump team impeller design in a water rig.

Garcia, R.↗
DOE OSTI2020

An effective field theory of quantum mechanical black hole horizons

We develop an effective theory which describes black holes with quantum mechanical horizons that is valid at scales long compared to the Schwarzschild radius but short compared to the lifetime of the black hole. Our formalism allows one to calculate the quantum mechanical effects in scattering processes involving black hole asymptotic states. We point out that the EFT Wightman functions which describe Hawking radiation in the Unruh vacuum are not Planck suppressed and are actually enhanced relative to those in the Boulware vacuum, for which such radiation is absent. We elaborate on this point showing how the non-Planck suppressed effects of Hawking radiation cancel in classical observables.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1993

A summary of microwave remote sensing investigations planned for BOREAS

The Boreal Ecosystem - Atmosphere Study (BOREAS) is a multidisciplinary field and remote sensing study that will be implemented jointly by the United States and Canada. The goal of BOREAS is to obtain an improved understanding of the interactions between the boreal forest biome and the atmosphere in order to clarify their roles in global change. Specific objectives are to improve the understanding of the processes that govern the exchanges of water, energy, heat, carbon, and trace gases between boreal ecosystems and the atmosphere, and to develop and validate remote sensing algorithms for transferring the understanding of these processes from local to regional scales. Two principal field sites, both within Canada, were selected. The northern site is located near Thompson, Manitoba, and the southern site encompasses Prince Albert National Park in Saskatchewan. The growing season in the northern site tends to be limited by growing-degree days while the southern site is limited by soil moisture and fire frequency. Most of the field work will occur at these two sites during 1993 and 1994 as part of six field campaigns. The first of these campaigns is scheduled for August 1993 and will involve instrument installation and an operational shakedown. Three large scale Intensive Field Campaigns (IFC's) are scheduled for 1994, along with two smaller scale Focused Field Campaigns (FFC's). The first 1994 campaign will be an FFC designed to capture the biome under completely frozen conditions during the winter. The second FFC and the first IFC are scheduled to capture the spring thaw period. Another IFC will take place in the summer during a period of maximum water stress. Finally, the third FFC will be scheduled to capture the collapse into senescence during the fall.

Mcdonald, Kyle C.↗
NASA NTRS2014

Oceanic Storm Characteristics off the Kennedy Space Center Coast

Natural cloud-to-ground lightning may behave differently depending on the characteristics of the attachment mediums, including the peak current (inferred from radiation fields) and the number of ground strike locations per flash. Existing literature has raised questions over the years on these characteristics of lightning over oceans, and the behaviors are not yet well understood. To investigate this we will obtain identical electric field observations over adjacent land and ocean regions during both clear air and thunderstorm periods. Oceanic observations will be obtained using a 3-meter NOAA buoy that has been instrumented with a Campbell Scientific electric field mill and New Mexico Techs slow antenna, to measure the electric fields aloft. We are currently obtaining measurements from this system on-shore at the Florida coast, to calibrate and better understand the behavior of the system in elevated-field environments. Sometime during winter 2013, this system will be moored 20NM off the coast of the Kennedy Space Center. Measurements from this system will be compared to the existing on-shore electric field mill suite of 31 sensors and a coastal slow antenna. Supporting observations will be provided by New Mexico Techs Lightning Mapping Array, the Eastern Range Cloud to Ground Lightning Surveillance System, and the National Lightning Detection Network. An existing network of high-speed cameras will be used to capture cloud-to-ground lightning strikes over the terrain regions to identify a valid data set for analysis. This on-going project will demonstrate the value of off-shore electric field measurements for safety-related decision making at KSC, and may improve our understanding of relative lightning risk to objects on the ground vs. ocean. This presentation will provide an overview of this new instrumentation, and a summary of our progress to date.

Ocean↗
NASA NTRS2006

WIND MEASUREMENTS WITH HIGH-ENERGY DOPPLER LIDAR

Coherent lidars at 2-micron wavelengths from holmium or thulium solid-state lasers have been in use to measure wind for applications in meteorology, aircraft wake vortex tracking, and turbulence detection [1,2,3] These field-deployed lidars, however, have generally been of a pulse energy of a few millijoules, limiting their range capability or restricting operation to regions of high aerosol concentration such as the atmospheric boundary layer. Technology improvements in the form of high-energy pulsed lasers, low noise detectors, and high optical quality telescopes are being evaluated to make wind measurements to long ranges or low aerosol concentrations. This research is aimed at developing lidar technology for satellite-based observation of wind on a global scale. The VALIDAR project was initiated to demonstrate a high pulse energy coherent Doppler lidar. VALIDAR gets its name from the concept of validation lidar, in that it can serve as a calibration and validation source for future airborne and spaceborne lidar missions. VALIDAR is housed within a mobile trailer for field measurements.

Koch, Grady J.↗
DOE OSTI2020

Recommended Target Fields for Commissioning the Vera C. Rubin Observatory

The commissioning team for the Vera C. Rubin observatory is planning a set of engineering and science verification observations with the Legacy Survey of Space and Time (LSST) commissioning camera and then the Rubin Observatory LSST Camera. The time frame for these observations is not yet fixed, and the commissioning team will have flexibility in selecting fields to observe. In this document, the Dark Energy Science Collaboration (DESC) Commissioning Working Group presents a prioritized list of target fields appropriate for testing various aspects of DESC-relevant science performance, grouped by season for visibility from Rubin Observatory at Cerro Pachon. Our recommended fields include Deep-Drilling fields (DDFs) to full LSST depth for photo-$z$ and shape calibration purposes, HST imaging fields to full depth for deblending studies, and an $\sim$200 square degree area to 1-year depth in several filters for higher-level validation of wide-area science cases for DESC. We also anticipate that commissioning observations will be needed for template building for transient science over a broad RA range. We include detailed descriptions of our recommended fields along with associated references. We are optimistic that this document will continue to be useful during LSST operations, as it provides a comprehensive list of overlapping data-sets and the references describing them.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗