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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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Ozone is detected by film coated with solid, such as rubrene, that reacts with ozone to degree proportional to concentration in sample gas. Gas flow is stopped, and film is heated to produce light (chemiluminescence) in proportion to amount of reacted material on sensor.
Device consists of hollow tube node of oxidation-resistant sulfonated fluorocarbon polymer. Tube absorbs moisture from air passing across inner and outer surfaces, causing change in polymer conductance. Change is related to change in water content in gas sample.
Compact device monitors specific chemiluminescent reaction of heated solid material such as 3,5 diaminobezoic or polyvinyl alcohol after contact with gas sample to detect and quantify nitrogen dioxide concentration.
Toggle mechanism is used to trap gas samples within small diameter metal tubes. Device is easily actuated and seals off without fracture.
The effect of preheat on the temperature and species distributions in propane flames stabilized on a NASA contraswirl can has been examined. Flames with compact stable structure, inner-swirler airflow of 0.0091 kg/s, outer-swirler-plus-bypass airflow of 0.0203 kg/s, and propane injected 1 mm upstream of the inner swirler hub have been selected for detailed study. Over the inlet-air-temperature range from 300 to 673 K the maximum temperature in the flame increased by 40 to 60 K per 100-K increase in inlet air temperature. The point of maximum temperature on the center line approached the exit plane as inlet air temperature was increased. Oxygen, CO, H2, and methane were found together in gas samples taken from the flame, including the regions of maximum flame temperature.
A flame tube combustor holding jet A fuel was used in experiments performed at a pressure of .3 Mpa and a reference velocity of 25 meters/second for three inlet air temperatures of 600, 700, and 800 K. The gas sample measurements were taken at locations 18 cm and 48 cm downstream of the perforated plate flameholder. Nonuniform fuel/air profiles were produced using a fuel injector by separately fueling the inner five fuel tubes and the outer ring of twelve fuel tubes. Six fuel/air profiles were produced for nominal overall equivalence ratios of .5 and .6. An example of three of three of these profiles and their resultant nitric oxide NOx emissions are presented. The uniform fuel/air profile cases produced uniform and relatively low profile levels. When the profiles were either center-peaked or edge-peaked, the overall mass-weighted nitric oxide levels increased.
All zirconia combustion chamber for testing fuels prevents "flashback" accidental extension of flame into fuel supply line. Chamber consists of hemispherical injector on base surrounded by hemispherical cap. Cap has two additional ports for thermocouple and gas sampling probes.
An ion source using the cyclotron resonance principle is described. A miniaturized ion source device is used in an air gap of a small permanent magnet with a substantially uniform field in the air gap of about 0.5 inch. The device and permanent magnet are placed in an enclosure which is maintained at a high vacuum (typically 10 to the minus 7th power) into which a sample gas can be introduced. The ion beam end of the device is placed very close to an aperture through which an ion beam can exit into the apparatus for an experiment.
The radiation-induced racemization of optically active amino acids by gamma radiation is investigated, and geochemical and cosmochemical implications of the reaction are discussed. Samples of solid or dissolved optically pure D and L amino acids were irradiated by Co-60 gamma radiation at a rate of 4 to 10 million rads/hr for time periods necessary to induce radiolysis of 50 to 70% of the sample. Gas chromatographic analysis of the products indicates that gamma radiation leads to the racemization of solid amino acids and aqueous solutions of their sodium but not hydrochloride salts, in proportion to the radiation dose received. Mechanisms for the radioracemization of solid amino acids and their sodium salts are discussed, and the absence of radioracemization in aqueous hydrochloride salts is accounted for. The effects of radioracemization on D/L amino acid ratios used in meteorite, geochronological and geothermal age determination are discussed, and implications of the observed radioracemization of isovaline for the determination of the primordial enantiomeric composition of the Murchison meteorite are considered.
Emissions of carbon dioxide, total oxides of nitrogen, unburned hydrocarbons, and carbon monoxide from an F100 afterburning two spool turbofan engine at simulated flight conditions are reported. Tests were run at Mach 0.8 at altitudes of 10.97 and 13.71 km (36,000 and 45,000 ft), and at Mach 1.2 at 13.71 km (45,000 ft). Emission measurements were made from intermediate power (nonafterburning) through maximum afterburning, using a single point gas sample probe traversed across the horizontal diameter of the exhaust nozzle. The data show that emissions vary with flight speed, altitude, power level, and radial position across the nozzle. Carbon monoxide emissions were low for intermediate and partial afterburning power. Unburned hydrocarbons were near zero for most of the simulated flight conditions. At maximum afterburning, there were regions of NOx deficiency in regions of high CO. The results suggest that the low NOx levels observed in the tests are a result of interaction with high CO in the thermal converter. CO2 emissions were proportional to local fuel air ratio for all test conditions.
A unique and useful family of ballistic trajectories to Halley's comet is described. The distinguishing feature of this family is that all of the trajectories return to the Earth's vicinity after the Halley intercept. It is shown that, in some cases, the original Earth-return path can be reshaped by Earth-swingby maneuvers to achieve additional small-body encounters. One mission profile includes flybys of the asteroid Geographos and comet Tempel-2 following the Halley intercept. Dual-flyby missions involving comets Encke and Borrelly and the asteroid Anteros are also discussed. Dust and gas samples are collected during the high-velocity (about 70 km/sec) flythrough of Halley, and then returned to a high-apogee Earth orbit. Aerobraking maneuvers are used to bring the sample-return spacecraft to a low-altitude circular orbit where it can be recovered by the Space Shuttle.
A development process is described which consists of design, fabrication, and preliminary test evaluations of three approaches to internal aerodynamic primary zone flow patterns: (1) conventional double vortex swirl stabilization; (2) reverse flow swirl stabilization; and (3) large single vortex flow system. Each concept incorporates special design features aimed at extending the performance capability of the small engine combustor. Since inherent geometry of these combustors result in small combustion zone height and high surface area to volume ratio, design features focus on internal aerodynamics, fuel placement, and advanced cooling. The combustors are evaluated on a full scale annular combustor rig. A correlation of the primary zone performance with the overall performance is accomplished using three intrusion type gas sampling probes located at the exit of the primary zone section. Empirical and numerical methods are used for designing and predicting the performance of the three combustor concepts and their subsequent modifications. The calibration of analytical procedures with actual test results permits an updating of the analytical design techniques applicable to small reverse flow annular combustors.
A study of the effects of fuel-air preparation characteristics on combustor performance and emissions at temperature and pressure ranges representative of actual gas turbine combustors is discussed. The effect of flameholding devices on the vaporization process and NOx formation is discussed. Flameholder blockage and geometry are some of the elements that affect the recirculation zone characteristics and subsequently alter combustion stability, emissions and performance. A water cooled combustor is used as the test rig. Preheated air and Jet A fuel are mixed at the entrance of the apparatus. A vaporization probe is used to determine percentage of vaporization and a gas sample probe to determine concentration of emissions in the exhaust gases. The experimental design is presented and experimental expected results are discussed.
Mass spectrometer analysis of gas samples collected during a cure cycle of polymer materials can be used as a process control technique. This technique is particularly helpful in studying the various types of solvents and resin systems used in the preparation of polymer materials and characterizing the chemical composition of different resin systems and their mechanism of polymerization.
The toxicology procedures developed for the Space Shuttle program to evaluate and eliminate contaminants in the cabin atmosphere characterized, and results from STS missions 1-5 are reviewed. Shuttle maximum-allowable-concentration standards (SMAC) equal to 10-50 percent of those established for normal 40-h work weeks on the ground have been established for a broad range of substances, and outgassing data are employed in choosing spacecraft construction materials. Gases are removed by the atmospheric revitalization system (CO2-removal bed, catalytic oxidizer, and dehumidifier). Whole-gas and adsorbed-gas samples are employed in ground-based and inflight measurements of contaminants: results are presented in tables. A total of 152 substances, of which 64 were well defined, were detected in STS-1-5. Only the toluene contamination on STS-2 (17 ppm compared to the SMAC of 20 ppm) was considered serious.
A computer code has been developed that calculates radiative properties of nonequilibrium air in the low-density regimes expected during the flight of aeroassisted, orbital transfer vehicles. From the given nonequilibrium thermodynamic state variables, the code calculates number densities of internal states and the accompanying emission and absorption characteristics. In addition, the code calculates the number density of the hypothetical gas in radiative equilibrium that produces the same radiation emission as the given nonequilibrium gas. Sample results are shown to demonstrate how the code predicts the nonlinear variation of radiation with density at low densities.
Two studies on the abiotic formation of amino acids are presented. The first study demonstrates the role of hydrogen cyanide as a precursor of amino acids detected in extracts of lunar samples. The formation of several amino acids, including glycine, alanine, aspartic acid, and glutamic acid, under conditions similar to those used for the analysis of lunar samples is demonstrated. The second study investigates the formation of hydrogen cyanide as well as amino acids from lunar-sample gas mixtures under electrical discharge conditions. These results extend the possibility of synthesis of amino acids to planetary bodies with primordial atmospheres less reducing than a mixture of methane, ammonia, hydrogen and water.
An experimental program demonstrated that fuel-rich catalytic combustion can be accomplished soot free as long as the combustion temperature is less than the temperature at the rich limit of combustion. Although soot was not measured directly, three pieces of data strongly suggest that it was not present: (1) the product gases were completely transparent and produced no radiation characteristic of soot, (2) measured reaction temperatures followed closely those calculated for equilibrium with no soot present, and (3) over 99 percent of the carbon was accounted for in the measured reaction products. Data for two catalyst configurations were taken along with gas samples at two locations downstream of the catalyst bed.