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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Titanium-Water Thermosyphon Gamma Radiation Exposure and Results

Titanium-water thermosyphons are being considered for use in heat rejection systems for fission power systems. Their proximity to the nuclear reactor will result in some gamma irradiation. Noncondensable gas formation from radiation-induced breakdown of water over time may render portions of the thermosyphon condenser inoperable. A series of developmental thermosyphons were operated at nominal operating temperature under accelerated gamma irradiation, with exposures on the same order of magnitude as that expected in 8 years of heat rejection system operation. Temperature data were obtained during exposure at three locations on each thermosyphon: evaporator, condenser, and condenser end cap. Some noncondensable gas was evident; however, thermosyphon performance was not affected because the noncondensable gas was compressed into the fill tube region at the top of the thermosyphon, away from the heat rejecting fin. The trend appeared to be an increasing amount of noncondensable gas formation with increasing gamma irradiation dose. Hydrogen is thought to be the most likely candidate for the noncondensable gas and hydrogen is known to diffuse through grain boundaries. Post-exposure evaluation of one thermosyphon in a vacuum chamber and at temperature revealed that the noncondensable gas diffused out of the thermosyphon over a relatively short period of time. Further research shows a number of experimental and theoretical examples of radiolysis occurring through gamma radiation alone in pure water.

Sanzi, James, L.A↗
NASA NTRS1983

Human respiration at rest in rapid compression and at high pressures and gas densities

The ventilation (V), end-tidal PCO2 (PACO2), and CO2 elimination rate were determined in men at rest breathing CO2-free gas over the pressure range 1-50 ATA and the gas density range 0.4-25 g/l, during slow and rapid compressions, at stable elevated ambient pressures and during slow decompressions. Progressive increase in pulmonary gas flow resistance due to elevation of ambient pressure and inspired gas density to the He-O2 equivalent of 5000 feet of seawater was found to produce a complex pattern of change in PACO2. It was found that as both ambient pressure and pulmonary gas flow resistance were progressively raised, PACO2 at first increased, went through a maximum, and then declined towards values near the 1 ATA level. It is concluded that this pattern of PACO2 change results from the interaction on ventilation of the increase in pulmonary resistance due to the elevation of gas density with the increase in respiratory drive postulated as due to generalized central nervous system excitation associated with exposure to high hydrostatic pressure. It is suggested that a similar interaction exists between increased gas flow resistance and the increase in respiratory drive related to nitrogen partial pressure and the resulting narcosis.

Gelfand, R.↗
NASA NTRS2012

Titanium-Water Thermosyphon Gamma Radiation Effects and Results

Titanium-water thermosyphons are being considered for use in heat rejection systems for fission power systems. Their proximity to the nuclear reactor will result in some exposure to gamma irradiation. Non-condensable gas formation from radiation may breakdown water over time and render a portion of the thermosyphon condenser inoperable. A series of developmental thermosyphons were operated at nominal operating temperature with accelerated gamma irradiation exposures on the same order of magnitude that is expected in eight years of heat rejection system operation. Temperature data were obtained during exposure at three locations on each thermosyphon; evaporator, condenser, and condenser end cap. Some non-condensable gas was evident, however thermosyphon performance was not affected because the non-condensable gas was compressed into the fill tube region at the top of the thermosyphon, away from the heat rejecting fin. The trend appeared to be an increasing amount of non-condensable gas formation with increasing gamma irradiation dose. Hydrogen is thought to be the most likely candidate for the non-condensable gas and hydrogen is known to diffuse through grain boundaries. Post-exposure evaluation of selected thermosyphons at temperature and in a vacuum chamber revealed that the non-condensable gas likely diffused out of the thermosyphons over a relatively short period of time. Further research shows a number of experimental and theoretical examples of radiolysis occurring through gamma radiation alone in pure water.

Sanzi, James L.↗
NASA NTRS1986

Compressible laminar boundary layer with real gas effects for flight conditions to M(e) = 8 and T(o) = 2500 K

One of the problems for the hypersonic flights is the lack of accurate methods for predicting the boundary layer parameters at high Mach numbers and temperatures. At high Mach numbers and temperatures, the real gas effects should be included in calculations of the compressible laminar and turbulent boundary layers. By introducing the Mangler-Levy-Lees transformation, the compressible laminar boundary layer equations were transformed into two ordinary differential equations. To solve these ordinary differential equations for the flow over a flat plate, the Runge-Kutta method of order 5 and 6 was used with a secant method of solving the simultaneous nonlinear equations for the boundary layer conditions. Instead of using the perfect gas assumptions, the properties of air in the temperature range of 100 to 2500 K at M(e) = 8 were used for the calculations. The calculations were carried out for free flight conditions. The real gas effects were significant for the conditions of high freestream Mach numbers, and the boundary layer parameters from the real gas solutions were quite different from the existing formulas and solutions.

Nagamatsu, H. T.↗
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 NTRS1960

Radiation Shielding of the Stagnation Region by Transpiration of an Opaque Gas

The laminar compressible boundary layer in the two-dimensional and axisymmetric stagnation regions has been analyzed to show the effects of the injection of a radiation absorbing foreign gas on an incident radiation field, and on the enthalpy profiles across the boundary layer. Total heat transfer to the stagnation region is evaluated for numerous cases and the results are compared with the no shielding case. Required absorption properties of the foreign gas are determined and compared with properties of known gases.

Howe, John Thomas↗
NASA NTRS1990

Device for quickly sensing the amount of O2 in a combustion product gas

A sensing device comprising an O2 sensor, a pump, a compressor, and a heater is provided to quickly sense the amount of O2 in a combustion product gas. A sample of the combustion product gas is compressed to a pressure slightly above one atmosphere by the compressor. Next, the heater heats the sample between 800 C and 900 C. Next, the pump causes the sample to be flushed against the electrode located in O2 sensor 6000 to 10,000 times per second. Reference air at approximately one atmosphere is provided to the electrode of O2 sensor. Accordingly, the O2 sensor produces a voltage which is proportional to the amount of oxygen in the combustion product gas. This voltage may be used to control the amount of O2 entering into the combustion chamber which produces the combustion product gas.

Singh, Jag J.↗
NASA NTRS1987

H-alpha Fabry-Perot interferometric observations of blue compact dwarf galaxies

H-alpha Fabry-Perot interferometric observations of the two blue compact dwarf galaxies (BCDs) 7 Zw 403 and 1 Zw 49 are presented. The velocity field of 7 Zw 403 shows no clear large-scale organized motion but the velocity field is not completely chaotic either. The gas associated with the 8 H II regions in 7 Zw 403 has neither the highest nor lowest velocities. The BCD 1 Zw 49 is dominated by a single H II region which is about 50 times brighter than any other feature in the galaxy. There is a chain of fainter H II regions extending across the galaxy. The velocity field is well ordered along the H II region chain, but it is very complex around the dominant H II region, suggesting H-alpha loops and filaments around the latter. Both BCDs show velocity gradients of about 25 km/s on scales of about 10 pc in 7 Zw 403 and of about 50 pc in 1 Zw 49. These velocity discontinuities compress the gas and are probably responsible for the star formation.

Thuan, Trinh Xuan↗
NASA NTRS1993

Evidence for the interaction of the IRS 16 wind with the ionized and molecular gas at the Galactic center

We present a number of high-resolution radio images showing evidence for the dynamical interaction of the outflow arising from the IRS 16 complex with the ionized gas associated with the Northern Arm of Sgr A West, and with the northwestern segment of the circumnuclear molecular disk which engulfs the inner few parsecs of the Galactic center. We suggest that the wind disturbs the dynamics of the Northern Arm within 0.1 pc of the center, is responsible for the waviness of the arm at larger distances, and is collimated by Sgr A West and the circumnuclear disk. The waviness is discussed in terms of the Rayleigh-Taylor instability induced by the ram pressure of the wind incident on the surface of the Northern Arm. Another consequence of this interaction is the strong mid-IR polarization of the Northern Arm in the vicinity of the IRS 16 complex which is explained as a result of the ram pressure of the wind compressing the gas and the magnetic field.

Yusef-Zadeh, Farhad↗
NASA NTRSDate not supplied

Real Time Nitrogen Monitoring and Quality Control System for NASA Astromaterials Collection

The Nitrogen system is a vital utility supporting the curation office within NASA's Astromaterials Re-search and Exploration Science (ARES) Division at the Johnson Space center (JSC). Since the Apollo samples were returned in 1969. It has played an essential role in preserving NASA’s astromaterial collections (now nine collections) by maintaining contamination-free, controlled environments required for long term curation and advanced scientific research. To meet the stringent purity requirements for contamination control, high purity modified Grade C Liquid Nitrogen (LN2) is delivered weekly by an industrial gas vendor to a 15,000-gallon tank located outside at NASA JSC near the ARES facility. This nitrogen is vital for creating an inert atmosphere to store the collection in, ensuring they are continuously shielded from contaminants and alterations through a constant N2purge. For most of the past 65 years deliveries of LN2 have required a CoA (Certificate of Analysis) prior to delivery. If those were not available, then LN2 deliver were sent to third-party laboratories for verification, creating an operational bottleneck and quality gap. To address this challenge and maintain rigorous quality control, NASA JSC Infrastructure and Astromaterials Acquisition & Curation Office initiated the development of an on-site Analytical Gas Sampling (AGS) Laboratory. Designed to streamline quality verification if a CoA unavailable, the AGS lab was constructed by a subcontractor in Newton, NJ. After a successful factory acceptance test conducted by the NASA ARES Infrastructure team, the lab was trans-ported to NASA JSC, where it was anchored and integrated into the site’s nitrogen pressure system using stainless steel, oxygen-cleaned tubing. The ARES nitrogen system was modified to provide parallel flows to the AGS lab for quality control and to the astromaterials collection labs for maintaining an inert environment. The AGS lab features two operational modes: (1)Primary: Gaseous Nitrogen (GN2) Quality Monitoring –The AGS system continuously samples the site’s GN2 supply every 15 minutes to ensure compliance with required purity levels. (2) Secondary: LN2 Quality Verification when a comprehensive CoA is not available, a cryogenic vaporizer converts LN2 to GN2, which is then analyzed for impurities: H₂, Ar, O₂, CO, CO₂, H₂O, and total hydrocarbons (THC). By significantly enhancing on-site analytical capabilities, the AGS lab eliminates reliance on external testing, ensures uninterrupted quality monitoring of the nitrogen pressure system, and reinforces NASA’s commitment to preserving pristine astromaterials under the highest standards of curation and research integrity.

glove box↗
NASA NTRS1974

Decameter type IV bursts associated with coronal transients

The characteristics of four moving type IV burst observed with a 65- to 20-MHz swept-frequency interferometer are discussed. All four bursts were associated with depletions in the electron content of the white light corona. Characteristics of the bursts are not unique i.e., they differ in source size, structure, duration, and their association with other radio bursts. Following Smerd and Dulk (1971), it is assumed that a shock wave, moving out from the flare site is responsible for the expansion of a magnetic arch or the ejection of a plasmoid which is observed as the usual type IV burst. Behind the shock wave, the compressed coronal gas moves outward, and as it expands it causes a depletion of electrons in the inner corona. After the passage of the shock wave, sometimes the coronal magnetic field structure is restored to its initial situation, as evidenced by the observation of homologous transients.

Gergely, T. E.↗
NASA NTRS1980

On the characteristics of centrifugal-reciprocating machines

A method of compressing helium gas for cryogenic coolers is presented which uses centrifugal force to reduce the forces on the connecting rod and crankshaft in the usual reciprocating compressor. This is achieved by rotating the piston-cylinder assembly at a speed sufficient for the centrifugal force on the piston to overcome the compressional force due to the working fluid. The rotating assembly is dynamically braked in order to recharge the working space with fluid. The intake stroke consists of decelerating the rotating piston-cylinder assembly and the exhaust stroke consists of accelerating the assembly.

Higa, W. H.↗
NASA NTRS1982

Numerical calculation of the parameters of the efflux from a helium dewar used for cooling of heat shields in a satellite

The parameters of the efflux from a helium dewar in space were numerically calculated. The flow was modeled as a one dimensional compressible ideal gas with variable properties. The primary boundary conditions are flow with friction and flow with heat transfer and friction. Two PASCAL programs were developed to calculate the efflux parameters: EFFLUZD and EFFLUXM. EFFLUXD calculates the minimum mass flow for the given shield temperatures and shield heat inputs. It then calculates the pipe lengths, diameter, and fluid parameters which satisfy all boundary conditions. Since the diameter returned by EFFLUXD is only rarely of nominal size, EFFLUXM calculates the mass flow and shield heat exchange for given pipe lengths, diameter, and shield temperatures.

Brendley, K.↗
NASA NTRS1982

Vehicle conversion to hybrid gasoline/alternative fuel operation

The alternative fuels considered are compressed natural gas (CNG), liquefied natural gas (LNG), liquid petroleum gas (LPG), and methanol; vehicles were required to operate in a hybrid or dual-fuel gasoline/alternative fuel mode. Economic feasibility was determined by comparing the costs of continued use of gasoline fuel with the use of alternative fuel and retrofitted equipment. Differences in the amounts of future expenditures are adjusted by means of a total life-cycle costing. All fuels studied are technically feasible to allow a retrofit conversion to hybrid gasoline/alternative fuel operation except for methanol. Conversion to LPG is not recommended for vehicles with more than 100,000 km (60,000 miles) of prior use. Methanol conversion is not recommended for vehicles with more than 50,00 km (30,000 miles).

Donakowski, T. D.↗