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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Measurements of admittances and characteristic combustion times of reactive gaseous propellant coaxial injectors

The results of an experimental investigation that was concerned with the quantitative determination of the capabilities of combustion processes associated with coaxial injectors to amplify and sustain combustor oscillations was described. The driving provided by the combustion process was determined by employing the modified standing-wave method utilizing coaxial injectors and air-acetylene mixtures. Analyses of the measured data indicate that the investigated injectors are capable of initiating and amplifying combustion instabilities under favorable conditions of injector-combustion coupling and over certain frequency ranges. These frequency ranges and the frequency at which an injector's driving capacity is maximum are observed to depend upon the equivalence ratio, the pressure drop across the injector orifices and the number of injector elements. The characteristic combustion times of coaxial injectors were determined from steady state temperature measurements.

Janardan, B. A.↗
NASA NTRS1986

Effect of elevated temperature and pressure on sprays from simplex swirl atomizers

An examination is made of the effects of air temperature and pressure on the spray quality of a moderately high capacity pressure swirl atomizer spraying jet-A and No. 2 diesel fuel. Drop size distributions, in terms of both Sauter mean diameter (SMD) and the width of the distribution given by the Rosin-Rammler N parameter, are determined over a variety of air conditions. Close to the nozzle, limited data suggest that the SMDs were a strong function of air density, but independent of air temperature. Trends of SMD and N are shown as a function of distance from the nozzle at all conditions, indicating some of the evaporation characteristics of fuel sprays.

Dodge, L. G.↗
NASA NTRS1957

A Study of the "toss Factor" in the Impact Testing of Cermets by the Izod Pendulum Test

The test method presented shows that the "toss energy" contributed by the apparatus for brittle materials is negligible. The total toss energy is considered to consist of two components. (a) recovered stored elastic energy and (b) kinetic energy contributed directly by the apparatus. The results were verified by high-speed motion pictures of the test in operation. From these photographs, velocities of tossed specimens were obtained and toss energy computed. In addition, impact energies of some titanium carbide base cermets and high-temperature alloys, as measured by the low-capacity Izod pendulum test, compare well with impact energies measured by the NACA drop test.

ALLOYS, HEAT-RESISTING↗
NASA NTRS1948

Effect of Distribution of Basket-Hole Area on Simulated Altitude Performance of 25 1/2-Inch-Diameter Annular-Type Turbojet Combustor

A simulated altitude performance of a 25 1/2-inch-diameter annular-type turbojet combustor was performed to determine the effect of the distribution of basket-hole area on the altitude operational limits of the engine as imposed by the combustor.Total pressure drop was recorded, as well as the effect of fuel-nozzle flow capacity,and fuel-nozzle spray angle for one basket configuration. General observations were made for all configurations regarding flames, extent of afterburning, and durability of the baskets.

Olson, Walter T.↗
NASA NTRS1989

A closed-cycle refrigerator for cooling maser amplifiers below 4 Kelvin

A helium refrigerator utilizing the Gifford-McMahon/Joule-Thomson (GM/JT) cycle was designed and tested to demonstrate the feasibility of using small closed-cycle refrigerators as an alternative to batch-filled cryostats for operating temperatures below 4 K. The systems could be used to cool low-noise microwave maser amplifiers located in large parabolic antennas. These antennas tilt vertically, making conventional liquid-filled dewars difficult to use. The system could also be used for a non-tilting beam waveguide antenna to reduce the helium consumption of a liquid helium cryostat. The prototype system is adjustable to provide 700 mW of cooling at 2.5 K to 3 W at 4.3 K. Performance of the unit is not significantly affected by physical orientation. The volume occupied by the refrigerator is less than 0.1 cu m. Two JT expansion stages are used to maximize cooling capacity per unit mass flow. The heat exchangers were designed to produce minimum pressure drop in the return gas stream. Pressure drop for the entire JT return circuit is less than 5 kpa at a mass flow of 0.06 g/sec when operating at 2.5 K.

Britcliffe, M.↗
NASA NTRS1990

Thermodynamic properties and crystallization kinetics at high liquid undercooling

The heat capacities of liquid and crystalline Au-Pb-Sb alloys in the glass-forming composition range were measured with droplet emulsion and bulk samples. Based on the measured C(sub p) data, the entropy, enthalpy, and Gibbs free energy functions of the eutectic, solid mixture, and undercooled liquid were determined as a function of undercooling and compared with theoretical predictions. The results indicate an isentropic temperature at 313 + or - 5 K, which agrees well with experimental data for the glass transition. A kinetics analysis of the nucleation undercooling response suggests that the proper choice for the Gibbs free energy change during crystallization is most important in analyzing the nucleation kinetics. By classical nucleation theory, the prefactors obtained, based on a variety of theoretical predictions for the driving force, can differ by six orders of magnitude. If the nucleation rates are extrapolated to high undercooling, the extrapolations based on measured heat capacity data show agreement, whereas the predicted nucleation rates are inconsistent with results from drop tower experiments. The implications for microg experiments are discussed.

Fecht, Hans J.↗
NASA NTRS1992

Modeling and analysis of the Space Station Freedom Active Thermal Control System radiators using SINDA/FLUINT

Detailed SINDA/FLUINT models have been developed to assess the adequacy of the Space Station Freedom External Thermal Control System's radiator design, as well as to simulate the effects of various operational scenarios. Design margins can be deduced by quantifying such real-world effects as flow maldistribution due to line-pressure drop and uneven heat loads. The factor which most reduced the heat-rejection capacity is an uneven heat load split between the two low temperature loops.

Andish, Kambiz K.↗
NASA NTRS2000

A Simulation Study of Paced TCP

In this paper, we study the performance of paced TCP, a modified version of TCP designed especially for high delay- bandwidth networks. In typical networks, TCP optimizes its send-rate by transmitting increasingly large bursts, or windows, of packets, one burst per round-trip time, until it reaches a maximum window-size, which corresponds to the full capacity of the network. In a network with a high delay-bandwidth product, however, Transmission Control Protocol's (TCPs) maximum window-size may be larger than the queue size of the intermediate routers, and routers will begin to drop packets as soon as the windows become too large for the router queues. The TCP sender then concludes that the bottleneck capacity of the network has been reached, and it limits its send-rate accordingly. Partridge proposed paced TCP as a means of solving the problem of queueing bottlenecks. A sender using paced TCP would release packets in multiple, small bursts during a round-trip time in which ordinary TCP would release a single, large burst of packets. This approach allows the sender to increase its send-rate to the maximum window size without encountering queueing bottlenecks. This paper describes the performance of paced TCP in a simulated network and discusses implementation details that can affect the performance of paced TCP.

Kulik, Joanna↗
NASA NTRS2006

Miniature Arcs for Synthesis of Carbon Nanotubes in Microgravity

Although many methods are available for producing single-walled carbon nanotubes (SWNTs), the conventional carbon arc process remains the most popular due to its simplicity and large production rate. In the carbon arc, SWNTs are catalytically synthesized by rapidly evaporating a graphite anode impregnated with NiN metal catalyst from which the nanotubes grow in an inert atmosphere. However, high temperatures inside the carbon arc generate strong buoyancy driven convection, and it is hypothesized that the non-uniform environment created by this flow has a large effect on the growth and morphology of the SWNTs. To study the effect of buoyancy on the arc process, a miniature carbon arc apparatus was developed to synthesize SWNTs in a microgravity environment substantially free from these strong convective flows. The reactor was operated for either 2.2 or 5 seconds during free-fall in the drop towers at the NASA Glenn Research Center. Two apparatus designs differing mainly in their production rate and power capacity were investigated. The first consisted of a miniaturized carbon arc employing a 1 mm diameter graphite anode and powered by a 0.54 F capacitor bank charged to 65 V. The second, larger apparatus employed a 4 mm diameter anode and was powered by a portable battery pack capable of providing in excess of 300 amps at 30 volts to the arc for the duration of a 5 second drop. Initial results indicated that transient heating is a very large effect in the short-duration drop tower carbon arcs, and thermal equilibrium of the arc plasma, buffer gas, and apparatus was not attained during the short microgravity periods. In addition, removal of the buoyant convection by the microgravity now allowed clear observation of large jets of evaporated carbon vapor streaming from the anode and mixing with the inert buffer gas. The initial mixing of these jets with the cold buffer gas combined with the thermal transient made it difficult to establish a uniform high temperature environment around the arc in the 2.1 to 5 second microgravity time interval, and even with a very high-powered arc, the arc region was cooler than in continuously operated arcs. Despite these difficulties, the miniature arc produced SWNTs in microgravity. However, given the large thermal transient to overcome, no dramatic difference in sample yield or composition was noted between normal gravity and q2-,andL%econd long microgravity runs.

Alford, J. M.↗
NASA NTRS2011

Design and Evaluation of a Water Recirculation Loop Maintenance Device for the Advanced Spacesuit Water Membrane Evaporator

A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The bed design further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a clear demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

Steele, John W.↗
NASA NTRS2012

Performance of a Water Recirculation Loop Maintenance Device and Process for the Advanced Spacesuit Water Membrane Evaporator

A water loop maintenance device and process to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been undergoing a performance evaluation. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the water recirculation maintenance device and process is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance process further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware. This

Rector, Tony↗
NASA NTRS2013

Performance of a Water Recirculation Loop Maintenance Device and Process for the Advanced Spacesuit Water Membrane Evaporator

A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The bed design further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

Steele, John W.↗
NASA NTRS2014

Performance of Water Recirculation Loop Maintentance Components for the Advanced Spacesuit Water Membrane Evaporator

Water loop maintenance components to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop have undergone a comparative performance evaluation with a second SWME water recirculation loop with no water quality maintenance. Results show the benefits of periodic water maintenance. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the evaluation of water recirculation maintenance components was to further enhance this advantage through the leveraging of fluid loop management lessonslearned from the International Space Station (ISS). A bed design that was developed for a UTAS military application, and considered for a potential ISS application with the Urine Processor Assembly, provided a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance cycle included the use of a biocide delivery component developed for ISS to introduce a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

Rector, Tony↗
NASA NTRS2014

Performance of Water Recirculation Loop Maintenance Components for the Advanced Spacesuit Water Membrane Evaporator

Water loop maintenance components to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop have undergone a comparative performance evaluation with a second SWME water recirculation loop with no water quality maintenance. Results show the benefits of periodic water maintenance. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the evaluation of water recirculation maintenance components was to further enhance this advantage through the leveraging of fluid loop management lessons learned from the International Space Station (ISS). A bed design that was developed for a UTAS military application, and considered for a potential ISS application with the Urine Processor Assembly, provided a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance cycle included the use of a biocide delivery component developed for ISS to introduce a biocide in a microgravity compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

Rector, Tony↗
NASA NTRS2012

Design and Evaluation of a Water Recirculation Loop Maintenance Device for the Advanced Spacesuit Water Membrane Evaporator

A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing sublimator technology. The driver for the development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high-capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit Transport Water Loop. The bed design further leverages a sorbent developed for the ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System. The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of crewed spaceflight Environmental Control and Life Support System hardware.

Steele, John W.↗
NASA NTRS2014

Performance of Water Recirculation Loop Maintenance Components for the Advanced Spacesuit Water Membrane Evaporator

Water loop maintenance components to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop have undergone a comparative performance evaluation with a recirculating control loop which had no water quality maintenance. Results show that periodic water maintenance can improve performance of the SWME. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage of this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing sublimator technology. The driver for the evaluation of water recirculation maintenance components was to enhance the robustness of the SWME through the leveraging of fluid loop management lessons learned from the International Space Station (ISS). A patented bed design that was developed for a United Technologies Aerospace System military application provided a low pressure drop means for water maintenance in the SWME recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance cycle included the use of a biocide delivery component developed for the ISS to introduce a biocide in a microgravity compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

Rector, Tony↗
NASA NTRS2017

Analysis of Convective Weather Impact on Pre-Departure Routing of Flights from Fort Worth Center to New York Center

In response to severe weather conditions, Traffic Managers specify flow constraints and reroutes to route air traffic around affected regions of airspace. Providing analysis and recommendations of available reroute options and associated airspace capacities would assist Traffic Managers in making more efficient decisions in response to convective weather. These recommendations can be developed by examining historical data to determine which previous reroute options were used in similar weather and traffic conditions. This paper describes the initial steps and methodology used towards this goal. The focus of this work is flights departing from Fort Worth Center destined for New York Center. Dominant routing structures used in the absence of convective weather are identified. A method to extract relevant features from the large volume of weather data available to quantify the impact of convective weather on this routing structure over a given time range is presented. Finally, a method of estimating flow rate capacity along commonly used routes during convective weather events is described. Results show that the flow rates drop exponentially as a function of the values of the proposed feature and that convective weather on the final third of the route was found to have a greater impact on the flow rate restriction than other portions of the route.

traffic flow management↗
NASA NTRSDate not supplied

A Two-Stage Regenerable Filter for Collection and Disposal of Carbon Fines

NASA is investigating the use of the Plasma Pyrolysis Assembly (PPA), which is a methane post-processing technology with the goal to recover hydrogen from the Carbon dioxide Reduction Assembly (CRA) currently onboard the International Space Station (ISS). The PPA can theoretically recover 75% of hydrogen from methane produced by the CRA. During methane processing the PPA creates roughly 40 mg/hr of carbon dust when operating at 4 crew member levels. The unwanted fines need to be removed from the stream to prevent any clogging of downstream components. The Regenerable Carbon Filter (RCF) was designed by Umpqua Research Company to address the carbon particulate created in the PPA. The RCF includes two stages. The first is an electrostatic precipitator designed to collect ultrafine particles. The second is a low pressure drop physical filter. Both filters are made of heat tolerant materials to allow regeneration of the filtration capacity by O2 oxidation of captured carbon. This paper will discuss the RCF hardware and test plans.

Filtration, Environmental Control, Life Support↗