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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Preliminary investigation of high power microwave plasmas for electrothermal thruster use

Results are reported from preliminary tests to evaluate the high power microwave electrothermal thruster concept, which employs a free-floating plasma discharge maintained by applied CW microwave power to heat a propellant gas flow. Stable plasmas have been created and maintained in He, N2, and H2 as propellants in both the TM(sub 011) and TM(sub 012) modes at discharge pressures from 10 Pa to 69 kPa. Vortical inflow of the propellant gas was observed to cause the formation of on-axis 'spike' plasmas. Operation in the spike plasma condition yields maximum power absorption with minimum wall heating and maximum propellant-heating efficiency; plasmas of the three propellant gases were investigated in the spike condition in an open channel to a maximum applied power level of 11.2 kW (in N2). Microwave power coupling efficiencies of over 90 percent were routinely obtained at absorbed power levels up to 2 kW. Magnetic nozzle effects were investigated with a superconducting solenoid Al magnet applying a high magnetic field to the plasmas in, and exiting from, the discharge tube.

Power, John L.↗
NASA NTRS1961

Radiation Heat Transfer

The pm-pose of this report is to describe work which has been carried out under the subject grant during the period from April 1, 1961, to October 1, 1961. Technical supervision and guidance of the work was provided by Mr. Seymour Lieblein, Chief, Flow Physics Branch, NASA Lewis Research Center, Cleveland, Ohio.

ABSORPTION↗
DOE OSTI2025

Emissions Characterization for Ammonia Fuel Blends in an Enclosed Swirl-Stabilized Diffusion Burner

This study investigates ammonia flames using the enclosed Sydney swirl burner (ESSB), focusing on detailed global emissions measurements. Emissions were measured via Fourier-transform-infrared (FTIR) spectrometer, utilizing a heated, long-path absorption cell. Hot, wet measurements of pertinent species were collected, and concentrations were determined via lineshape fitting in conjunction with the HITRAN database. Results show that partially cracked ammonia compositions yield lower emissions compared to pure NH3/H2, and small amounts of NH3 addition to CH4-containing fuel blends exhibit high levels of NOx and CO, with measurable HCN and unburnt CH4. Equilibrium calculations suggest trade-offs between chemical timescale, heat loss, and mixing. Future work will explore emissions sampling procedures and expand analysis using chemical reactor network modelling.

ammonia combustion↗
NASA NTRS1977

Analytical study of effects of surface and environmental thermal properties on moisture in composites

The influence of surface and environmental thermal properties on the moisture absorption in fiber-reinforced polymeric-resin-matrix composite materials which have been subjected to convection and solar radiation was studied. Predicted moisture contents based on the conditions at the heated surface and in the ambient air were compared for both short term and long term exposures over a wide range of values for emittance, solar absorptance, convective heat transfer coefficient, solar radiation, ambient temperature, and orientation of the surface with respect to the sun. The calculations showed that absorptance and heat transfer coefficient have significant effects on the moisture content.

Tompkins, S. S.↗
NASA NTRS1971

The Determination of Trace Metals in Saline Waters and Biological Tissues Using the Heated Graphite Atomizer

A selective, volatalization technique utilizing the heated graphite atomizer atomic absorption technique has been developed for the analysis of iron in sea water. A similar technique may be used to determine vanadium, copper, nickel and cobalt in saline waters when their concentrations are higher than those normally encountered'in unpolluted sea waters. A preliminary solvent extraction using ammonium pyrolidine dithiocarbamate and methyl iso-butyl ketone permits the determination of a number of elements including iron, copper, zinc, nickel, cobalt and lead in sea water. The heated graphite atomized technique has also been applied to the determination of a range of trace transition elements in marine plant and animal tissues.

Segar, D. A.↗
NASA NTRS1992

Theoretical studies of the physics of the solar atmosphere

Significant advances in our theoretical basis for understanding several physical processes related to dynamical phenomena on the sun were achieved. We have advanced a new model for spicules and fibrils. We have provided a simple physical view of resonance absorption of MHD surface waves; this allowed an approximate mathematical procedure for obtaining a wealth of new analytical results which we applied to coronal heating and p-mode absorption at magnetic regions. We provided the first comprehensive models for the heating and acceleration of the transition region, corona, and solar wind. We provided a new view of viscosity under coronal conditions. We provided new insights into Alfven wave propagation in the solar atmosphere. And recently we have begun work in a new direction: parametric instabilities of Alfven waves.

Hollweg, Joseph V.↗
NASA NTRS1993

Preliminary investigation of high power microwave plasmas for electrothermal thruster use

Results are reported from preliminary tests to evaluate the high power microwave electrothermal thruster (MET) concept, which employs a free-floating plasma discharge maintained by applied CW microwave power to heat a propellant gas flow. Stable plasmas have been created and maintained in helium (He), nitrogen (N2), and hydrogen (H2) as propellants in both the TM(sub 011) and TM(sub 012) modes at discharge pressures from 10 Pa to 69 kPa. Reproducible starting conditions of pressure and power have been documented for all the plasmas. Vortical inflow of the propellant gas was observed to cause the formation of on-axis 'spike' plasmas. The formation and unformation conditions of these plasmas were studied. Operation in the spike plasma condition enables maximum power absorption with minimum wall heating and offers maximum efficiency in heating the propellant gas. In the spike condition, plasmas of the three propellant gases were investigated in an open channel configuration to a maximum applied power level of 11.2 kW (in N2). Microwave power coupling efficiencies of over 90 percent were routinely obtained at absorbed power levels up to 2 kW. Magnetic nozzle effects were investigated with a superconducting solenoid Al magnet applying a high magnetic field to the plasmas in and exiting from the discharge tube.

Power, John L.↗
NASA NTRS2001

Ocean-Science Mission Needs: Real-Time AUV Data for Command, Control, and Model Inputs

Predictive models for tides, hydrodynamics, and bio-optical properties affecting the visibility and buoyancy of coastal waters are needed to evaluate the safety of personnel and equipment engaged in maritime operations under potentially hazardous conditions. Predicted currents can be markedly different for two-layer systems affected by terrestrial runoff than for well-mixed conditions because the layering decouples the surface and bottom Ekman layers and rectifies the current response to oscillatory upwelling-and downwelling-favorable winds. Standard ocean models (e.g. Princeton Ocean Model) require initial-and boundary data on the physical and optical properties of the multilayered water column to provide accurate simulations of heat budgets and circulation. Two observational systems are designed to measure vertically structured conditions on the West Florida Shelf (WFS): a tethered buoy network and an autonomous underwater vehicle (AUV) observational system. The AUV system is described with a focus on the observational systems that challenge or limit the communications command and control network for various types of measurement programs. These include vertical oscillatory missions on shelf transects to observe the optical and hydrographic properties of the water column, and bottom-following missions for measuring the bottom albedo. Models of light propagation, absorption, and conversion to heat as well as determination of the buoyancy terms for physical models require these measurements. High data rates associated with video bottom imagery are the most challenging for the real-time, command and control communications system, but they are met through a combination of loss-less and lossy data-compression methods, depending upon the data-rate of the radio links.

Carder, Kendall L.↗
DOE OSTI2022

Cloud adjustments from large-scale smoke–circulation interactions strongly modulate the southeastern Atlantic stratocumulus-to-cumulus transition

Smoke from southern Africa blankets the southeastern Atlantic Ocean from June to October, producing strong and competing aerosol radiative effects. Smoke effects on the transition between overcast stratocumulus and scattered cumulus clouds are investigated along a Lagrangian (air-mass-following) trajectory in regional climate and large eddy simulation models. Results are compared with observations from three recent field campaigns that took place in August 2017: ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES), CLouds and Aerosol Radiative Impacts and Forcing: Year 2017 (CLARIFY), and Layered Atlantic Smoke Interactions with Clouds (LASIC). The case study is set up around the joint ORACLES–CLARIFY flight that took place near Ascension Island on 18 August 2017. Smoke sampled upstream on an ORACLES flight on 15 August 2017 likely entrained into the marine boundary layer later sampled during the joint flight. The case is first simulated with the WRF-CAM5 regional climate model in three distinct setups: (1) FireOn, in which smoke emissions and any resulting smoke–cloud–radiation interactions are included; (2) FireOff, in which no smoke emissions are included; (3) RadOff, in which smoke emissions and their microphysical effects are included but aerosol does not interact directly with radiation. Over the course of the Lagrangian trajectory, differences in free tropospheric thermodynamic properties between FireOn and FireOff are nearly identical to those between FireOn and RadOff, showing that aerosol–radiation interactions are primarily responsible for the free tropospheric effects. These effects are non-intuitive: in addition to the expected heating within the core of the smoke plume, there is also a “banding” effect of cooler temperature (~1–2 K) and greatly enhanced moisture (>2 g kg -1 ) at the plume top. This banding effect is caused by a vertical displacement of the former continental boundary layer in the free troposphere in the FireOn simulation resulting from anomalous diabatic heating due to smoke absorption of sunlight that manifests primarily as a few hundred meters per day reduction in large-scale subsidence over the ocean. A large eddy simulation (LES) is then forced with free tropospheric fields taken from the outputs for the WRF-CAM5 FireOn and FireOff runs. Cases are run by selectively perturbing one variable (e.g., aerosol number concentration, temperature, moisture, vertical velocity) at a time to better understand the contributions from different indirect (microphysical), “large-scale” semi-direct (above-cloud thermodynamic and subsidence changes), and “local” semi-direct (below-cloud smoke absorption) effects. Despite a more than 5-fold increase in cloud droplet number concentration when including smoke aerosol concentrations, minimal differences in cloud fraction evolution are simulated by the LES when comparing the base case with a perturbed aerosol case with identical thermodynamic and dynamic forcings. A factor of 2 decrease in background free tropospheric aerosol concentrations from the FireOff simulation shifts the cloud evolution from a classical entrainment-driven “deepening–warming” transition to trade cumulus to a precipitation-driven “drizzle-depletion” transition to open cells, however. The thermodynamic and dynamic changes caused by the WRF-simulated large-scale adjustments to smoke diabatic heating strongly influence cloud evolution in terms of both the rate of deepening (especially for changes in the inversion temperature jump and in subsidence) and in cloud fraction on the final day of the simulation (especially for the moisture “banding” effect). Such large-scale semi-direct effects would not have been possible to simulate using a small-domain LES model alone.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2022

Cloud Adjustments From Large-Scale Smoke–Circulation Interactions Strongly Modulate the Southeastern Atlantic Stratocumulus-to-Cumulus Transition

Smoke from southern Africa blankets the southeastern Atlantic Ocean from June to October, producing strong and competing aerosol radiative effects. Smoke effects on the transition between overcast stratocumulus and scattered cumulus clouds are investigated along a Lagrangian (air-mass-following) trajectory in regional climate and large eddy simulation models. Results are compared with observations from three recent field campaigns that took place in August 2017: ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES), CLouds and Aerosol Radiative Impacts and Forcing: Year 2017 (CLARIFY), and Layered Atlantic Smoke Interactions with Clouds (LASIC). The case study is set up around the joint ORACLES–CLARIFY flight that took place near Ascension Island on 18 August 2017. Smoke sampled upstream on an ORACLES flight on 15 August 2017 likely entrained into the marine boundary layer later sampled during the joint flight. The case is first simulated with the WRF-CAM5 regional climate model in three distinct setups: (1) FireOn, in which smoke emissions and any resulting smoke–cloud–radiation interactions are included; (2) FireOff, in which no smoke emissions are included; (3) RadOff, in which smoke emissions and their microphysical effects are included but aerosol does not interact directly with radiation. Over the course of the Lagrangian trajectory, differences in free tropospheric thermodynamic properties between FireOn and FireOff are nearly identical to those between FireOn and RadOff, showing that aerosol–radiation interactions are primarily responsible for the free tropospheric effects. These effects are non-intuitive: in addition to the expected heating within the core of the smoke plume, there is also a “banding” effect of cooler temperature (∼1–2 K) and greatly enhanced moisture (>2 g kg−1) at the plume top. This banding effect is caused by a vertical displacement of the former continental boundary layer in the free troposphere in the FireOn simulation resulting from anomalous diabatic heating due to smoke absorption of sunlight that manifests primarily as a few hundred meters per day reduction in large-scale subsidence over the ocean. A large eddy simulation (LES) is then forced with free tropospheric fields taken from the outputs for the WRF-CAM5 FireOn and FireOff runs. Cases are run by selectively perturbing one variable (e.g., aerosol number concentration, temperature, moisture, vertical velocity) at a time to better understand the contributions from different indirect (microphysical), “large-scale” semi-direct (above-cloud thermodynamic and subsidence changes), and “local” semi-direct (below-cloud smoke absorption) effects. Despite a more than 5-fold increase in cloud droplet number concentration when including smoke aerosol concentrations, minimal differences in cloud fraction evolution are simulated by the LES when comparing the base case with a perturbed aerosol case with identical thermodynamic and dynamic forcings. A factor of 2 decrease in background free tropospheric aerosol concentrations from the FireOff simulation shifts the cloud evolution from a classical entrainment-driven “deepening–warming” transition to trade cumulus to a precipitation-driven “drizzle-depletion” transition to open cells, however. The thermodynamic and dynamic changes caused by the WRF-simulated large-scale adjustments to smoke diabatic heating strongly influence cloud evolution in terms of both the rate of deepening (especially for changes in the inversion temperature jump and in subsidence) and in cloud fraction on the final day of the simulation (especially for the moisture “banding” effect). Such large-scale semi-direct effects would not have been possible to simulate using a small-domain LES model alone.

southeast Atlantic Ocean↗
DOE OSTI2021

Lab-scaled performance evaluation of novel water-lean solvents for post combustion CO 2 capture

Here, this work focuses on demonstrating the energetic performance and operational reliability in a continuous system of RTI's water-lean solvents for post-combustion CO 2 capture applications. RTI's Non-Aqueous Solvent, NAS-1A was subjected to 100 h of continuous, CO 2 capture and regeneration operation using a Lab-scale Gas Absorption System (LsGAS) while the CO 2 capture efficiency, mass balance, and total energy inputs were monitored. Throughout the test period, NAS-1A demonstrated stable operation with 90% CO 2 capture while requiring about 15% lower total energy input for solvent regeneration compared to 30 wt% monoethanolamine (MEA) solution. The use of a slipstream of CO 2 -rich solvent from the absorber sump reduced the regenerated CO 2 temperature before the gas was further cooled by the overhead condenser at the top of the desorber. The rich-split setup combined with a wash section may be an effective approach to remove water and solvent vapor from the regenerated CO 2 as well as to recover heat at the top of the desorber. NAS-1B was later developed and included a modifier component that lowers the heat of CO 2 absorption and reduces the vapor pressure of the amine component. The total energy inputs for 90% CO 2 capture with NAS-1B was found to be 25% less than that of the MEA. A gas chromatograph was used to monitor the amine concentration in the gas leaving the absorber wash section. It was found that under similar operating conditions, the presence of the modifier in NAS-1B reduces the amine in the absorber off-gas from 143 ppm in NAS-1A to 20 ppm.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1988

Laser production and heating of plasma for MHD application

Experiments have been made on the production and heating of plasmas by the absorption of laser radiation. These experiments were performed to ascertain the feasibility of using laser-produced or laser-heated plasmas as the input for a magnetohydrodynamic (MHD) generator. Such a system would have a broad application as a laser-to-electricity energy converter for space power transmission. Experiments with a 100-J-pulsed CO2 laser were conducted to investigate the breakdown of argon gas by a high-intensity laser beam, the parameters (electron density and temperature) of the plasma produced, and the formation and propagation of laser-supported detonation (LSD) waves. Experiments were also carried out using a 1-J-pulsed CO2 laser to heat the plasma produced in a shock tube. The shock-tube hydrogen plasma reached electron densities of approximately 10 to the 17th/cu cm and electron temperatures of approximately 1 eV. Absorption of the CO2 laser beam by the plasma was measured, and up to approximately 100 percent absorption was observed. Measurements with a small MHD generator showed that the energy extraction efficiency could be very large with values up to 56 percent being measured.

Jalufka, N. W.↗
NASA NTRS1969

Technique for predicting temperature distribution in gases

Simple algebraic equations enable calculation of the temperature distribution throughout a heat generating, radiation gas. They apply over the entire range of opacities, for any heat flux, for a temperature dependent absorption coefficient, and for a non-uniform distribution of volumetric heat sources.

Kascak, A.↗
DOE OSTI2022

Quantum-cascade-laser-absorption-spectroscopy diagnostic for temperature, pressure, and NO X 2 Π 1/2 at 500 kHz in shock-heated air at elevated pressures

The design, validation, and application of a quantum-cascade-laser-absorption-spectroscopy diagnostic for measuring gas temperature, pressure, and nitric oxide (NO) in high-temperature air are presented. A distributed-feedback quantum-cascade laser (QCL) centered near 1976 c m − <#comment/> 1 was used to scan across two transitions of NO in its ground electronic state ( X 2 Π <#comment/> 1 / 2 ). A measurement rate of 500 kHz was achieved using a single QCL by: (1) performing current modulation through a bias-tee, and (2) targeting closely spaced transitions with a large difference in lower-state energy. The diagnostic was validated in a mixture of 95% argon and 5% NO, which was shock-heated to ≈ <#comment/> 2000 to 3700 K. The average mean percent differences between laser-absorption-spectroscopy (LAS) measurements and predictions from shock-jump relations for temperature, pressure, and NO mole fraction were 3.1%, 4.1%, and 6.5%, respectively. The diagnostic was then applied to characterize shock-heated air at high temperatures (up to ≈ <#comment/> 5500 K ) and high pressures (up to 12 atm) behind either incident or reflected shocks. The LAS measurements were compared to theoretical predictions from shock-jump relations, pressure sensors mounted in the wall of the shock tube, and equilibrium values of the NO mole fraction. The average mean percent differences between LAS measurements and their aforementioned reference values were 3.2%, 10.8%, and 10.4% for temperature, pressure, and NO mole fraction, respectively. Last, a comparison between a measured NO mole fraction time history and a time-stepped homogeneous reactor simulation performed using two different chemical kinetics mechanisms is presented.

Gilvey, Jonathan J. (ORCID:0000000317664383)↗
DOE OSTI2022

Reconfigurable Electrical Networks within a Conductive Hydrogel Composite

Soft materials that exhibit compliance, programmability, and reconfigurability can have a transformative impact as electronic skin for applications in wearable electronics/soft robotics. There has been significant progress in soft conductive materials; however, achieving electrically controlled and reversible changes in conductivity and circuit connectivity remains challenging. To overcome this limitation, a soft material architecture with reconfigurable conductive networks of silver flakes embedded within a hydrogel matrix is presented. The conductive networks can be reversibly created/disconnected through various stimuli, including current, humidity, or temperature. Such stimuli affect electrical connectivity of the hydrogel by controlling its water content, which can be modulated by evaporation under ambient conditions (passive dehydration), evaporation through electrical Joule heating (active dehydration), or absorption of additional water (rehydration). The resulting change in electrical conductivity is reversible and repeatable, endowing the composite with on-demand reconfigurable conductivity. To highlight this material's unique properties, it is shown that conductive traces can be reconfigured after severe damage and revert to lower conductivity after rehydration. Additionally, a quadruped robot is demonstrated that can respond to stimuli by changing direction following exposure to excess water, thereby achieving reprogrammable locomotion behaviors.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Physical, numerical, and computational challenges of modeling neutrino transport in core-collapse supernovae

The proposal that core collapse supernovae are neutrino driven is still the subject of active investigation more than 50 years after the seminal paper by Colgate and White. The modern version of this paradigm, which we owe to Wilson, proposes that the supernova shock wave is powered by neutrino heating, mediated by the absorption of electron-flavor neutrinos and antineutrinos emanating from the proto-neutron star surface, or neutrinosphere. Neutrino weak interactions with the stellar core fluid, the theory of which is still evolving, are flavor and energy dependent. The associated neutrino mean free paths extend over many orders of magnitude and are never always small relative to the stellar core radius. Thus, neutrinos are never always fluid like. Instead, a kinetic description of them in terms of distribution functions that determine the number density of neutrinos in the six-dimensional phase space of position, direction, and energy, for both neutrinos and antineutrinos of each flavor, or in terms of angular moments of these neutrino distributions that instead provide neutrino number densities in the four-dimensional phase-space subspace of position and energy, is needed. In turn, the computational challenge is twofold: (i) to map the kinetic equations governing the evolution of these distributions or moments onto discrete representations that are stable, accurate, and, perhaps most important, respect physical laws such as conservation of lepton number and energy and the Fermi–Dirac nature of neutrinos and (ii) to develop efficient, supercomputer-architecture-aware solution methods for the resultant nonlinear algebraic equations. In this review, we present the current state of the art in attempts to meet this challenge.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Into the net zero emissions and climate change control: From solid carbon waste to effective solar convertors

Here, in this work, we demonstrate the potential for solar-to-heat conversion of carbon byproducts and their outstanding effects to reduce anthropogenic emissions. Those carbon byproducts are soots (biomass, evaporated carbon, etc.) as well as morphed graphenes. Our results cover optical characterization to demonstrate their suitability as heat capacitors and solar-to-heat convertors. Our raw materials are sustainable and currently considered environmental pollutants that require true attention to minimize global warming effects. Fortunately, they are ideal candidates to reduce the carbon footprints and can contribute towards a true net-zero environmental transition. We explore and demonstrate that soots are among the most competitive materials to transform solar energy into heat due to their absorption capacity, and durability. These materials are more competitive than commercial products and other known solar convertors demonstrating the superior thermosolar benefits. The best candidate is biomass with solar absorptivity, light emission, and cost reduction of 96, 85% and 15-fold, respectively, when compare to commercial products. Biomass and soot have comparable or better solar conversion characteristics, and sustainability than pristine carbon nanostructures and they are up to 3 orders of magnitude cheaper.

14 SOLAR ENERGY↗