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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2006

Processing and Properties of a Phenolic Composite System

Phenolic resin systems generate water as a reaction by-product via condensation reactions during curing at elevated temperatures. In the fabrication of fiber reinforced phenolic resin matrix composites, volatile management is crucial in producing void-free quality laminates. A commercial vacuum-bag moldable phenolic prepreg system was selected for this study. The traditional single-vacuum-bag (SVB) process was unable to manage the volatiles effectively, resulting in inferior voidy laminates. However, a double vacuum bag (DVB) process was shown to afford superior volatile management and consistently yielded void-free quality parts. The DVB process cure cycle (temperature /pressure profiles) for the selected composite system was designed, with the vacuum pressure application point carefully selected, to avoid excessive resin squeeze-outs and achieve the net shape and target resin content in the final consolidated laminate parts. Laminate consolidation quality was characterized by optical photomicrography for the cross sections and measurements of mechanical properties. A 40% increase in short beam shear strength, 30% greater flexural strength, 10% higher tensile and 18% higher compression strengths were obtained in composite laminates fabricated by the DVB process.

Hou, Tan-Hung↗
NASA NTRS2007

Precise Measurement of Carbon Dioxide Column by Passive Ground Based Sensor

Over the past four years we have developed a family of differential radiometers based upon the Fabry-Perot interferometers that exhibit very great sensitivity to changes in the atmospheric column of carbon dioxide, oxygen, and water vapor. Our instruments employ a solid Fabry-Perot etalon that is tuned to the proper wavelength by changing its temperature. The thickness of the etalon has been selected so that its multiple pass bands align with regularly space absorption features of the molecule under investigation. Using multiple absorption features improves the optical throughput of the instrument and improves the stability of the instrument response with respect to environmental changes. We are presently working to extend this technique to the carbon 13 isotope of carbon dioxide and to methane. Our instruments are intrinsically rugged and can be fabricated in a small package at relatively low cost.. As such they hold promise for widespread use in ground based networks for calibration and validation of satellite instruments such as OCO and GOSAT. Results will be presented for long term ground based operations of these systems. The effects of atmospheric scattering, pointing errors, pressure broadening and temperature effects will be discussed with regard to achieving precision better than .5% required for validation of carbon dioxide column measured from space. Finally we will outline the approach for extension of this methodology to additional molecular species of interest.

Heaps, William S.↗
NASA NTRS2010

Flame Retardant Effect of Aerogel and Nanosilica on Engineered Polymers

Aerogels are typically manufactured vIa high temperature and pressure-critical-point drying of a colloidal metal oxide gel filled with solvents. Aerogel materials derived from silica materials represent a structural morphology (amorphous, open-celled nanofoams) rather than a particular chemical constituency. Aerogel is not like conventional foams in that it is a porous material with extreme microporosity and composed of individual features only a few nanometers in length with a highly porous dendriticlike structure. This unique substance has unusual properties such as low thermal conductivity, refractive index and sound suppression; in addition to its exceptional ability to capture fast moving dust. The highly porous nature of the aerogel's structure provides large amounts of surface area per unit weight. For instance, a silica aerogel material with a density of 100 kilograms per cubic meters can have surface areas of around 800 to 1500 square meters per gram depending on the precursors and process utilized to produce it. To take advantage of the unique properties of silica aerogels, especially the ultra light weight and low thermal conductivity, their composites with various engineering polymers were prepared and their flammability was investigated by Cone Calorimetry. The flammability of various polystyrene/silica aerogel nanocomposites were measured. The combination of these nanocomposites with a NASA patented flame retardant SINK were also studied. The results were compared with the base polymer to show the differences between composites with different forms of silica.

Williams, Martha K.↗
NASA NTRS2012

Multi-Objective Optimization of a Turbofan for an Advanced, Single-Aisle Transport

Considerable interest surrounds the design of the next generation of single-aisle commercial transports in the Boeing 737 and Airbus A320 class. Aircraft designers will depend on advanced, next-generation turbofan engines to power these airplanes. The focus of this study is to apply single- and multi-objective optimization algorithms to the conceptual design of ultrahigh bypass turbofan engines for this class of aircraft, using NASA s Subsonic Fixed Wing Project metrics as multidisciplinary objectives for optimization. The independent design variables investigated include three continuous variables: sea level static thrust, wing reference area, and aerodynamic design point fan pressure ratio, and four discrete variables: overall pressure ratio, fan drive system architecture (i.e., direct- or gear-driven), bypass nozzle architecture (i.e., fixed- or variable geometry), and the high- and low-pressure compressor work split. Ramp weight, fuel burn, noise, and emissions are the parameters treated as dependent objective functions. These optimized solutions provide insight to the ultrahigh bypass engine design process and provide information to NASA program management to help guide its technology development efforts.

Berton, Jeffrey J.↗
NASA NTRS2015

Pressure-Equalizing Cradle for Booster Rocket Mounting

A launch system and method improve the launch efficiency of a booster rocket and payload. A launch aircraft atop which the booster rocket is mounted in a cradle, is flown or towed to an elevation at which the booster rocket is released. The cradle provides for reduced structural requirements for the booster rocket by including a compressible layer, that may be provided by a plurality of gas or liquid-filled flexible chambers. The compressible layer contacts the booster rocket along most of the length of the booster rocket to distribute applied pressure, nearly eliminating bending loads. Distributing the pressure eliminates point loading conditions and bending moments that would otherwise be generated in the booster rocket structure during carrying. The chambers may be balloons distributed in rows and columns within the cradle or cylindrical chambers extending along a length of the cradle. The cradle may include a manifold communicating gas between chambers.

Rutan, Elbert L.↗
NASA NTRS2015

Comparison of Venous Return Characteristics with Right Ventricular Mechanics During Cephalic Fluid Shift

For my summer internship project, I organized a pilot study to analyze the effects of a cephalic fluid shift on venous return and right ventricular mechanics to increase right ventricular and venous knowledge. To accomplish this pilot study, I wrote a testing protocol, obtained Institutional Review Board (IRB) approval, completed subject payment forms, lead testing sessions, and analyzed the data. This experiment used -20deg head down tilt (20 HDT) as the ground based simulation for the fluid shift that occurs during spaceflight and compared it to data obtained from the seated and supine positions. Using echocardiography, data was collected for the right ventricle, hepatic vein, internal jugular vein, external jugular vein, and inferior vena cava. Additionally, non-invasive venous pressure measurements, similar to those soon to be done in-orbit, were collected. It was determined that the venous return from below the heard is increased during 20 HDT, which was supported by increased hepatic vein velocities, increased right ventricular inflow, and increased right ventricular strain at 20 HDT relative to seated values. Jugular veins in the neck undergo an increase in pressure and area, but no significant increase in flow, relative to seated values when a subject is tilted 20 HDT. Contrary to the initial expectations based on this jugular flow, there was no significant increase in central venous pressure, as evidenced by no change in Doppler indices for right arterial pressure or inferior vena cava diameter. It is suspected that these differences in pressure are due to the hydrostatic pressure indifference point shifting during tilt; there is a potential for a similar phenomenon with microgravity. This data will hopefully lead to a more in-depth understanding of the response of the body to microgravity and how those relate to the previously mentioned cardiovascular risk of fluid shift that is associated with spaceflight. These results were presented in greater detail to the Cardiovascular Laboratory and the Space Life Science Summer Institute, which helped me prepare for future graduate school research presentations. This internship allowed me to apply and expand the anatomy, physiology, and mechanics information I learned during my undergraduate degree in Biomedical Engineering to the cardiovascular system with the unique zero gravity perspective. Additionally, I was able to develop skills with data analysis techniques involving speckle tracking for ventricular strain and Doppler waveforms for blood velocities. Additionally, I was able to expand upon my previous work in the Cardiovascular Laboratory by writing a literature review on a data analysis project I completed last summer. Ultimately, this internship and venous relationship comparison project provided me with a significant learning experience and additional skill sets, which are applicable to my goals of attaining a Ph.D. in biomedical engineering with a focus on tissue engineering and the cardiovascular system.

Elliott, Morgan↗
NASA NTRS2017

Simulation of the Ozone Monitoring Instrument Aerosol Index Using the NASA Goddard Earth Observing System Aerosol Reanalysis Products

We provide an analysis of the commonly used Ozone Monitoring Instrument (OMI) aerosol index (AI) product for qualitative detection of the presence and loading of absorbing aerosols. In our analysis, simulated top-of-atmosphere (TOA) radiances are produced at the OMI footprints from a model atmosphere and aerosol profile provided by the NASA Goddard Earth Observing System (GEOS-5) Modern-Era Retrospective Analysis for Research and Applications aerosol reanalysis (MERRAero). Having established the credibility of the MERRAero simulation of the OMI AI in a previous paper we describe updates in the approach and aerosol optical property assumptions. The OMI TOA radiances are computed in cloud-free conditions from the MERRAero atmospheric state, and the AI is calculated. The simulated TOA radiances are fed to the OMI aerosol retrieval algorithms, and its retrieved AI (OMAERUV AI) is compared to the MERRAero calculated AI. Two main sources of discrepancy are discussed: one pertaining the OMI algorithm assumptions of the surface pressure, which are generally different from what the actual surface pressure of an observation is, and the other related to simplifying assumptions in the molecular atmosphere radiative transfer used in the OMI algorithms. Surface pressure assumptions lead to systematic biases in the OMAERUV AI, particularly over the oceans. Simplifications in the molecular radiative transfer lead to biases particularly in regions of topography intermediate to surface pressures of 600hPa and 1013.25hPa. Generally, the errors in the OMI AI due to these considerations are less than 0.2 in magnitude, though larger errors are possible, particularly over land. We recommend that future versions of the OMI algorithms use surface pressures from readily available atmospheric analyses combined with high-spatial resolution topographic maps and include more surface pressure nodal points in their radiative transfer lookup tables.

remote sensing↗
NASA NTRSDate not supplied

Feasibility Study of a Carbon Dioxide Breathing, Solid-Fueled Ramjet for Martian Descent and Landing of Human Class Payloads

This study analyzes the cross-range capabilities of solid-fueled ramjets in a Martian atmosphere for applications in entry, descent, and landing. Trajectories and engine operability are characterized using Mach and dynamic pressure operational points. It is predicted that use of atmosphere-breathing propulsion will enable access to additional surface latitudes without the need for orbital plane changes. Development of an integrated design environment facilitates preliminary ramjet design and analysis, and enables sensitivity studies to identify high impact areas of technology development. In addition, additive manufacturing supports prototyping, rapid ground testing, and allows for utilization of complex geometries.

Shi Broadwell↗
NASA NTRS2023

Quiet Spacecraft Cabin Ventilation Fan: Vibration Measurements Results

Quiet, efficient fans with minimal vibrations are needed to maximize the mechanical life of atmospheric revitalization system fans used for human life support systems for long duration space exploration missions. Several metal spacecraft cabin ventilation fan prototypes have been designed, built, and tested at the NASA Glenn Research Center Acoustical Testing Laboratory. Tests performed in 2021 of the first prototype of the metal fan measured vibrations greater than desired at design point speed and backpressure conditions. To try to reduce those vibrations, a second prototype of the fan design was developed which included a new lighter rotor with a tighter balance tolerance, a new collet to attach the rotor to the motor shaft more securely and repeatably, and a new bracket to center and hold the motor in the fan centerbody more precisely. The second prototype of the fan was tested in 2023 and the vibrations were measured with the fan operating at design point speeds in isolation but not throttled to design point back pressure conditions since it was not installed with inlet and exhaust ducting. Peak vibration was reduced from 4 mm/s to 1 mm/s. This paper is part of a series of reports documenting the performance of the prototype fan.

Fan↗
NASA NTRSDate not supplied

Space Suit Portable Life Support System Oxygen Regulator History, Development, & Testing Results

An oxygen regulator has been in development for the Exploration Extravehicular Mobility Unit (xEMU) Portable Life Support System (PLSS). The regulator provides the necessary oxygen pressure control for the crew member during prebreathe, Extra-Vehicular Activity (EVA), post EVA airlock operations, and Decompression Sickness (DCS) treatment. It has been over four decades since a new spacesuit oxygen regulator has been designed. The regulator and EMU that is presently used on the International Space Station (ISS) was developed for the space shuttle program without any significant changes made throughout its service life. The xEMU spacesuit oxygen regulator is based on the previous EMU Secondary Oxygen Pack (SOP). The new design integrates numerous improvements and changes including an innovative approach to regulator architecture, a more robust first stage pressure sensing mechanism, digital actuation control, and electronic pressure sensing. These upgrades replace manual control linkages, physical gauges, and enable infinitely variable pressure set points. The new setpoints can decrease prebreathe time and make in suit DCS treatment possible. Throughout its four iterations design concerns have been addressed, safety features have been added, and the envelope of the regulator designed to fit inside the xEMU PLSS package. This paper will review the history, design, testing, and lessons learned during the development of the xEMU PLSS Oxygen Regulator.

Ryan Eric Ogilvie↗
NASA NTRSDate not supplied

Space Suit Portable Life Support System (PLSS) Oxygen Regulator History, Development, & Testing Results

An oxygen regulator has been in development for the Exploration Extravehicular Mobility Unit (xEMU) Portable Life Support System (PLSS). The regulator provides the necessary oxygen pressure control for the crew member during prebreathe, Extra-Vehicular Activity (EVA), post EVA airlock operations, and Decompression Sickness (DCS) treatment. It has been over four decades since a new spacesuit oxygen regulator has been designed. The regulator and EMU that is presently used on the International Space Station (ISS) was developed for the space shuttle program without any significant changes made throughout its service life. The xEMU spacesuit oxygen regulator is based on the previous EMU Secondary Oxygen Pack (SOP). The new design integrates numerous improvements and changes including an innovative approach to regulator architecture, a more robust first stage pressure sensing mechanism, digital actuation control, and electronic pressure sensing. These upgrades replace manual control linkages, physical gauges, and enable infinitely variable pressure set points. The new setpoints can decrease prebreathe time and make in suit DCS treatment possible. Throughout its four iterations design concerns have been addressed, safety features have been added, and the envelope of the regulator designed to fit inside the xEMU PLSS package. This paper will review the history, design, testing, and lessons learned during the development of the xEMU PLSS Oxygen Regulator.

Ryan Ogilvie↗
NASA NTRS1975

Turbulent pressure field in a co-annular jet

Single point and two-point fluctuating static pressure measurements have been made in the initial mixing and transition regions in a co-annular circular jet. Space scales, correlation and time scales in the convected frame, and convection velocities have been determined for both broad band and narrow band frequency components. Analytical functionals describing the structural behavior of the turbulent pressure field have been developed from the data which are suitable for direct application in predicting the sound power level radiated from this turbulent field. Effects of both area and velocity ratios are incorporated in the model.

Hammersley, R. J.↗
NASA NTRS1980

Applications of liquid state physics to the earth's core

New results derived for application to the earth's outer core using the modern theory of liquids and the hard-sphere model of liquid structure are presented. An expression derived in terms of the incompressibility and pressure is valid for a high-pressure liquid near its melting point, provided that the pressure is derived from a strongly repulsive pair potential; a relation derived between the melting point and density leads to a melting curve law of essentially the same form as Lindemann's law. Finally, it is shown that the 'core paradox' of Higgins and Kennedy (1971) can occur only if the Gruneisen parameter is smaller than 2/3, and this constant is larger than this value in any liquid for which the pair potential is strongly repulsive.

Stevenson, D. J.↗
NASA NTRS1991

Static pressure measurements in A 30 kWe class arcjet

A series of cold and hot flow static pressure measurements have been made as a function of distance along the principal axis of a 30 kWe arcjet. During these experiments, the background pressure was varied from atmospheric pressure to less than 1 Torr. The experimental arcjet used in these tests had the same constrictor and conical nozzle dimensions as the baseline MOD-1 ammonia arcjet developed at NASA-JPL, but used nitrogen as the propellant gas. Comparison of the measured static pressure profiles with the arc erosion patterns on the anode surface showed that anode arc attachment points directly coincided with the minimum static pressure points. The dual voltage modes commonly observed in 30 kWe class arcjet thrusters are also believed to be caused by the presence of two pressure minima in the arcjet, one at the constrictor entrance and the other in the expansion nozzle. The static pressure profiles also suggest that the sonic flow transition occurs at the entrance to the nozzle, indicating the existence of very thick boundary layers in the arcjet constrictor.

Harris, William J.↗
NASA NTRS1990

Controlling Gas-Flow Mass Ratios

Proposed system automatically controls proportions of gases flowing in supply lines. Conceived for control of oxidizer-to-fuel ratio in new gaseous-propellant rocket engines. Gas-flow control system measures temperatures and pressures at various points. From data, calculates control voltages for electronic pressure regulators for oxygen and hydrogen. System includes commercially available components. Applicable to control of mass ratios in such gaseous industrial processes as chemical-vapor depostion of semiconductor materials and in automotive engines operating on compressed natural gas.

Morris, Brian G.↗
NASA NTRS2014

Ice Crystal Icing Engine Testing in the NASA Glenn Research Center's Propulsion Systems Laboratory: Altitude Investigation

The National Aeronautics and Space Administration (NASA) conducted a full scale ice crystal icing turbofan engine test using an obsolete Allied Signal ALF502-R5 engine in the Propulsion Systems Laboratory (PSL) at NASA Glenn Research Center. The test article used was the exact engine that experienced a loss of power event after the ingestion of ice crystals while operating at high altitude during a 1997 Honeywell flight test campaign investigating the turbofan engine ice crystal icing phenomena. The test plan included test points conducted at the known flight test campaign field event pressure altitude and at various pressure altitudes ranging from low to high throughout the engine operating envelope. The test article experienced a loss of power event at each of the altitudes tested. For each pressure altitude test point conducted the ambient static temperature was predicted using a NASA engine icing risk computer model for the given ambient static pressure while maintaining the engine speed.

Altitude Testing↗
NASA NTRS1975

The possibility of using superconductive systems in the analysis of the composition of cosmic rays

The experimental results on the use of superconductive systems onboard of spacecraft are described. To ensure low temperatures in the cryostat under weightlessness, helium was used at a pressure above the critical pressure. In flight, the temperature was controlled at six points, while the pressure and intensity of the magnetic field were controlled in the solenoids. The methodical test proved it possible to mount special installations on satellites, with extensive magnetic fields based on superconductive alloys, and particularly, low weights and low power consumption magnetic analyzers.

Anashkin, O. P.↗