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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS2014

A Noise and Emissions Assessment of the N3-X Transport

Analytical predictions of certification noise and exhaust emissions for NASA's N3-X - a notional, hybrid wingbody airplane - are presented in this paper. The N3-X is a 300-passenger concept transport propelled by an array of fans distributed spanwise near the trailing edge of the wingbody. These fans are driven by electric motors deriving power from twin generators driven by turboshaft engines. Turboelectric distributed hybrid propulsion has the potential to dramatically increase the propulsive efficiency of aircraft. The noise and exhaust emission estimates presented here are generated using NASA's conceptual design systems analysis tools with several key modifications to accommodate this unconventional architecture. These tools predict certification noise and the emissions of oxides of nitrogen by leveraging data generated from a recent analysis of the N3-X propulsion system.

Berton, Jeffrey J.↗
NASA NTRS1989

Longitudinal aerodynamic characteristics of a subsonic, energy-efficient transport configuration in the National Transonic Facility

The Reynolds number, aeroelasticity, boundary layer transition, and nonadiabatic wall temperature effects, and data repeatability was determined in the National Transonic Facility (NTF) for a subsonic, energy efficient transport model. The model was tested over a Mach number range of 0.50 to 0.86 and a Reynolds number range of 1.9 million to approximately 23.0 million (based on mean geometric chord). The majority of the data was taken using cryogenic nitrogen (data at 1.9 million Reynolds number was taken in air). Force and moment, wing pressure, and wing thermocouple data are presented. The data indicate that increasing Reynolds number resulted in greater effective camber of the supercritical wing and horizontal tail, resulting in greater lift and pitching moment coefficients at nearly all angles of attack for M = 0.82. As Reynolds number was increased, untrimmed L/D increased, the angle of attack for maximum L/D decreased, drag creep was reduced significantly, and drag divergence Mach number increased slightly. Data repeatability for both modes of operation of the NTF (air and cryogenic nitrogen) was generally very good, and nonadiabatic wall effects were estimated to be small. Transition-free and transition-fixed configurations had significantly different force and moment data at M = 0.82 for low Reynolds number, and very small differences were noted at high Reynolds numbers.

Jacobs, Peter F.↗
NASA NTRS2001

Thermal Performance of Biological Substance Systems in Vitro Under Static and Dynamic Conditions at the Cryogenic Test Laboratory, NASA Kennedy Space Center, USA

A unique research program, including a comprehensive study of thermal performance at cryogenic vacuum insulation systems, was performed at the NASA Kennedy Space Center. The main goal was to develop a new soft vacuum system (from 1 torr to 10 torr) that provides an intermediate level of performance (k-value below 4.8 mW/m-K). Liquid nitrogen boil-off methods were used to test conventional materials, novel materials, and certain combinations. The test articles included combinations of aluminum foil, fiberglass paper, polyester fabric, silica aerogel composite blanket, fumed silica, silica aerogel powder, and syntactic foam. A new LCI system was developed at the Cryogenics Test Laboratory. This system performs exceptionally well at soft vacuum levels and nearly as good as an MLI at high vacuum levels. Apparent thermal conductivities for the LCI range from 2 mW/m-K at soft vacuum to 0.1 mW/m-K at high vacuum. Several cryostats were designed, constructed, and calibrated by the Cryogenics Test Laboratory at KSC NASA as part of this research program. The cryostat test apparatus is a liquid nitrogen boil-off calorimeter system for direct measurement of the apparent thermal conductivity at a fixed vacuum level between 5 x 10(exp -5) and 760 torr. The apparatus is also used for transient measurements of temperature profiles. The development of efficient, robust cryogenic insulation systems has been a targeted area of research for a number of years. Improved methods of characterization, testing, and evaluation of complex biological substance systems for cryosurgery and cryobiology are the focus of this paper.

Augustynowicz, S. D.↗
NASA NTRS1971

Electron-bombardment ion source operation using various gases.

Description of a modified flight-type SERT II ion thruster operated with xenon, krypton, argon, neon, nitrogen, helium, and carbon dioxide. The discharge performance with xenon, krypton, and argon was found to be similar to that obtained previously with mercury. Mass spectrometer data indicated that xenon could be operated efficiently with no significant multiple ionization. Restriction of the beam area, with an associated decrease in discharge potential, was necessary to reduce multiple ionization with argon to a negligible level. This modification also resulted in more stable operation of the thruster. Performance with the remaining gases was poor, but some future performance improvements may be realizable.

Byers, D. C.↗
NASA NTRS1977

Handbook on Hypergolic Propellant Discharges and Disposal

The efficiency of all treatment methods formerly or currently used in treating chemical wastes is assessed with emphasis on the disposal of hypergolic propellants. Maximum focus is on the space shuttle propellants MMH and N2O4. Except for hydrogen peroxide oxidizers, all the propellants are nitrogen based and can be potentially reduced to valuable plant nutrients. In theory, all the propellants can be reduced to carbon, hydrogen, nitrogen, and oxygen, except of fuming nitric acid which contains a small amount of fluorine. Appendices cover: (1) a general design criteria for disposal ponds; (2) thermal aspects of reaction in dilute solution; (3) gas bubble growth, detachment, and rise (4) absorption scrubber fundamentals and descriptions; (5) separation of a propellant vapor from a helium stream by permeation; and (6) atmospheric emission limits.

Bowman, T. E.↗
NASA NTRS1982

Supercritical water oxidation for wastewater treatment Preliminary study of urea destruction

Supercritical water oxidation is being investigated as a method of treating spacecraft wastewater for recycle. In this process, oxidation is conducted in an aqueous phase maintained above the critical temperature (374 C) and pressure (215 bar) of water. Organic materials are oxidized with efficiencies greater than 99.99 percent in residence times of less than 1 minute. This paper presents preliminary results for urea destruction. Above 650 C, urea can be completely broken down to nitrogen gas, carbon dioxide and water by supercritical water oxidation, without the use of a specific catalyst.

Timberlake, S. H.↗
NASA NTRS1989

Infrared ground-based astronomy with the Hughes 256 X 256 PtSi array

It is shown that large format PtSi Schottky diode infrared arrays, the Hughes 256 X 256 hybrid Schottky array in particular, are competitive alternatives to the smaller format photovoltaic arrays for ground-based astronomy. The modest quantum efficiency of the PtSi compared to the photovoltaic devices is more than compensated for by the larger format. The use of hybrid technology yields effective fill factors of nearly 100 percent, and the low dark current, noise, excellent imaging characteristics, cost, and solid nitrogen operating temperature add to the effectiveness of this array for ground-based imaging. In addition to discussing the characteristics of this array, researchers present laboratory test data and astronomical results achieved at Kitt Peak.

Fowler, A.↗
NASA NTRS2013

Characterization of Microbial Communities Found in Bioreactor Effluent

The purpose of this investigation was to examine microbial communities of simulated wastewater effluent from hollow fiber membrane bioreactors collected from the Space Life Science Laboratory and Texas Technical University. Microbes were characterized using quantitative polymerase chain reaction where a total count of bacteria and fungi were determined. The primers that were used to determine the total count of bacteria and fungi were targeted for 16S rDNA genes and the internal transcribed spacer, respectively. PCR products were detected with SYBR Green I fluorescent dye and a melting curve analysis was performed to identify unique melt profiles resulting from DNA sequence variations from each species of the community. Results from both the total bacteria and total fungi count assays showed that distinct populations were present in isolates from these bioreactors. This was exhibited by variation in the number of peaks observed on the melting curve analysis graph. Further analysis of these results using species-specific primers will shed light on exactly which microbes are present in these effluents. Information gained from this study will enable the design of a system that can efficiently monitor microbes that play a role in the biogeochemical cycling of nitrogen in wastewater on the International Space Station to assist in the design of a sustainable system capable of converting this nutrient.

Flowe, Candice↗
NASA NTRS2022

The Effects of Surface Fossil Magnetic Fields on Massive Star Evolution: IV. Grids of Models at Solar, LMC, and SMC Metallicities

Magnetic fields can drastically change predictions of evolutionary models of massive stars via mass-loss quenching, magnetic braking, and efficient angular momentum transport, which we aim to quantify in this work. We use the MESA software instrument to compute an e xtensiv e main-sequence grid of stellar structure and evolution models, as well as isochrones, accounting for the effects attributed to a surface fossil magnetic field. The grid is densely populated in initial mass (3–60 M ), surface equatorial magnetic field strength (0–50 kG), and metallicity (representative of the Solar neighbourhood and the Magellanic Clouds). We use two magnetic braking and two chemical mixing schemes and compare the model predictions for slowly rotating, nitrogen- enriched (‘Group 2’) stars with observations in the Large Magellanic Cloud. We quantify a range of initial field strengths that allow for producing Group 2 stars and find that typical values (up to a few kG) lead to solutions. Between the subgrids, we find notable departures in surface abundances and evolutionary paths. In our magnetic models, chemical mixing is al w ays less efficient compared to non-magnetic models due to the rapid spin-down. We identify that quasi-chemically homogeneous main sequence evolution by efficient mixing could be prevented by fossil magnetic fields. We recommend comparing this grid of evolutionary models with spectropolarimetric and spectroscopic observations with the goals of (i) revisiting the derived stellar parameters of known magnetic stars, and (ii) observationally constraining the uncertain magnetic braking and chemical mixing schemes.

stars: abundances↗
NASA NTRS2003

Fuel cell environmental life cycle assessment : a progress report

Energy generation using fuel cells offers the possibility of high conversion efficiency and reduced pollution. Thus, in the futue, conventional methods of energy generation using coalfired power plants, natural gas turbines and internal combustion engines can potentially be replaced by fuel cells. The United States, Japan and several countries in Europe are currently developing fuel cells for transportation, distributed energy generation and portable electronics applications. On a system basis, the efficiency of chemical to electrical energy conversion in fuel cells can be as high as 45%. Also, because of the lower operating temperatures compared to turbines and internal combustion engines, emissions such as carbon monoxide and nitrogen oxides are extremely small. An assessment of the environmental impact of fuel cells over the entire lifecycle is needed to determine the specific benefits in various application scenarios. Such a comparative pollutants assessment must include a "cradle to grave" approach encompassing fuel production, fuel transportation, materials/manufacturing processes, waste management, and recycling. A comparative pollutant model would be a useful tool for industry and government in estimating energy savings and environmental credits, and providing a holistic understanding on regulatory needs. Another important benefit would be the ability to make appropriate comparisons with competitive energy generation technologies such as hybrids, turbines, and internal combustion engines, and to set up realistic targets. Also, exercising the model will assist in the initial screening for potential hot spots and showstoppers and focus on the right component technologies design for manufacturing, designs for input substitution and waste minimization, and prevent any unforeseen burdens.

Narayanan, S. R.↗
NASA NTRS1981

Performance and emissions characteristics of aqueous alcohol fumes in a DI diesel engine

A single cylinder DI Diesel engine was fumigated with ethanol and methanol in amounts up to 55% of the total fuel energy. The effects of aqueous alcohol fumigation on engine thermal efficiency, combustion intensity and gaseous exhaust emissions were determined. Assessment of changes in the biological activity of raw particulate and its soluble organic fraction were also made using the Salmonella typhimurium test. Alcohol fumigation improved thermal efficiency slightly at moderate and heavy loads, but increased ignition delay at all operating conditions. Carbon monoxide and unburned hydrocarbon emission generally increased with alcohol fumigation and showed no dependence on alcohol type or quality. Oxide of nitrogen emission showed a strong dependence on alcohol quality; relative emission levels decreased with increasing water content of the fumigant. Particulate mass loading rates were lower for ethanol fueled conditions. However, the biological activity of both the raw particulate and its soluble organic fraction was enhanced by ethanol fumigation at most operating conditions.

Heisey, J. B.↗
NASA NTRS1979

Lean, premixed, prevaporized combustor conceptual design study

Phase 1 of the Lean Premixed-Prevaporized Comubstor Design Study is a nine month analytical study effort with no experimental or testing activities included. The program has the objective to design and analyze advanced combustor concepts with features for fuel premixing and prevaporization upstream of the combustion zone for use in future subsonic aircrafts with features for fuel premixing and prevaporization upstream of the combustion zone for use in future subsonic aircraft engines. All of the designs also embody some form of variable geometry for combustor flow modulation. The primary criterion for these designs is low oxides of nitrogen emissions at stratospheric cruise conditions. Four combustor concepts are being designed for the NASA/GE Energy Efficient Engine (EEE) envelope and cycle. Current status of the program is that the four concepts sized for the EEE were designed and are currently undergoing analysis and evaluation.

Ekstedt, E. E.↗
NASA NTRS1986

Improving adsorption cryocoolers by multi-stage compression and reducing void volume

It is shown that the performance of gas adsorption cryocoolers is greatly improved by using adsorbents with low void volume within and between individual adsorbent particles (reducing void volumes in plumbing lines), and by compressing the working fluid in more than one stage. Refrigerator specific power requirements and compressor volumetric efficiencies are obtained in terms of adsorbent and plumbing line void volumes and operating pressures for various charcoal adsorbents using an analytical model. Performance optimization curves for 117.5 and 80 K charcoal/nitrogen adsorption cryocoolers are given for both single stage and multistage compressor systems, and compressing the nitrogen in two stages is shown to lower the specific power requirements by 18 percent for the 117.5 K system.

Bard, S.↗
NASA NTRS1992

Dependence of the cathodoluminescence of diamond films on deposition temperature

The deposition temperature dependence of the cathodoluminescence (CL) of diamond thin films grown by microwave-plasma-assisted chemical vapor deposition has been investigated. Depositions were made in the temperature range of 400 to 750 C at a pressure of 10 Torr, with a gas mixture of 5 percent CH4 and 5 percent O2 in hydrogen. The intensity of the luminescent peak at 430 nm was used as a measure of diamond quality for the film. This peak was found to be a maximum above 600 C. Examination of the intensities of CL emissions associated with nitrogen and silicon impurities at 530, 560, and 740 nm indicate incorporation of these impurities is more efficient at temperatures above 600 C. Film quality was thus found to be an optimization of competing mechanisms, i.e., improvement of diamond quality as evidenced by the intensity of the 430 nm peak, with the apparent activation of impurities and vacancy defects at elevated temperatures.

Shing, Y. H.↗
NASA NTRS2002

Development of High Quantum Efficiency UV/Blue Photocathode Epitaxial Semiconductor Heterostructures for Scintillation and Cherenkov Radiation Detection

The primary goal of this research project was to further extend the use of advanced heteroepitaxial-semiconductor crystal growth techniques such as molecular beam epitaxy (MBE) and to demonstrate significant gains in UV/blue photonic detection by designing and fabricating atomically-tailored heteroepitaxial GaAlN/GaInN photocathode device structures. This NASA Explorer technology research program has focused on the development of photocathodes for Cherenkov and scintillation radiation detection. Support from the program allowed us to enhance our MBE system to include a nitrogen plasma source and a magnetic bearing turbomolecular pump for delivery and removal of high purity atomic nitrogen during GaAlN/GaInN film growth. Under this program we have also designed, built and incorporated a cesium activation stage. In addition, a connected UHV chamber with photocathode transfer/positioner components as well as a hybrid phototube stage was designed and built to make in-situ quantum efficiency measurements without ever having to remove the photocathodes from UHV conditions. Thus we have constructed a system with the capability to couple atomically-tailored MBE-grown photocathode heterostructures with real high gain readout devices for single photon detection evaluation.

Leopold, Daniel J.↗
NASA NTRS2001

Quick Cooling and Filling Through a Single Port for Cryogenic Transfer Operations

Improved technology for the efficient transfer of cryogens is needed for future on-orbit fueling and remote Lunar/Mars operations. The cooling and filling of a liquid nitrogen (LN2) test vessel through a single port were investigated in a series of experiments. A new 'in-space' transfer tube design concept was used to demonstrate the ability to quickly cool and load cryogens through a single feed-through connection. Three different fill tube configurations with three different diameters were tested. The tubes providing the quickest cooldown time and the quickest fill time for the test article tank were determined. The results demonstrated a clear trade-off between cooling time and filling time for the optimum tube design. This experimental study is intended to improve technology for future flight tank designs by reducing fill system size, complexity, heat leak rate, and operations time. These results may be applied to Space Shuttle Power Reactant Storage and Distribution (PRSD) System upgrades and other future applications. Further study and experimental analysis for optimization of the fill tube design are in progress.

Jones, J. R.↗
NASA NTRS2007

Advanced Chemical Propulsion System Study

A detailed; mission-level systems study has been performed to show the benefit resulting from engine performance gains that will result from NASA's In-Space Propulsion ROSS Cycle 3A NRA, Advanced Chemical Technology sub-topic. The technology development roadmap to accomplish the NRA goals are also detailed in this paper. NASA-Marshall and NASA-JPL have conducted mission-level studies to define engine requirements, operating conditions, and interfaces. Five reference missions have been chosen for this analysis based on scientific interest, current launch vehicle capability and trends in space craft size: a) GTO to GEO, 4800 kg, delta-V for GEO insertion only approx.1830 m/s; b) Titan Orbiter with aerocapture, 6620 kg, total delta V approx.210 m/s, mostly for periapsis raise after aerocapture; c) Enceladus Orbiter (Titan aerocapture) 6620 kg, delta V approx.2400 m/s; d) Europa Orbiter, 2170 kg, total delta V approx.2600 m/s; and e) Mars Orbiter, 2250 kg, total delta V approx.1860 m/s. The figures of merit used to define the benefit of increased propulsion efficiency at the spacecraft level include propulsion subsystem wet mass, volume and overall cost. The objective of the NRA is to increase the specific impulse of pressure-fed earth storable bipropellant rocket engines to greater than 330 seconds with nitrogen tetroxide and monomothylhydrazine propellants and greater than 335 , seconds with nitrogen tetroxide and hydrazine. Achievement of the NRA goals will significantly benefit NASA interplanetary missions and other government and commercial opportunities by enabling reduced launch weight and/or increased payload. The study also constitutes a crucial stepping stone to future development, such as pump-fed storable engines.

Portz, Ron↗
NASA NTRS2008

Effect of Nitrogen Gas on the Lifetime of Carbon Nanotube Field Emitters for Electron-Impact Ionization Mass Spectrometry

The lifetime of a patterned carbon nanotube film is evaluated for use as the cold cathode field emission ionization source of a miniaturized mass spectrometer. Emitted current is measured as a function of time for varying partial pressures of nitrogen gas to explore the robustness and lifetime of carbon nanotube cathodes near the expected operational voltages (70-100 eV) for efficient ionization in mass spectrometry. As expected, cathode lifetime scales inversely with partial pressure of nitrogen. Results are presented within the context of previous carbon nanotube investigations, and implications for planetary science mass spectrometry applications are discussed.

Getty, Stephanie A.↗