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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Behavior of aircraft antiskid breaking systems on dry and wet runway surfaces: A slip-ratio-controlled system with ground speed reference from unbraked nose wheel

An experimental investigation was conducted at the Langley aircraft landing loads and traction facility to study the braking and cornering response of a slip ratio controlled aircraft antiskid braking system with ground speed reference derived from an unbraked nose wheel. The investigation, conducted on dry and wet runway surfaces, utilized one main gear wheel, brake, and tire assembly of a DC-9 series 10 airplane. During maximum braking, the average ratio of the drag force friction coefficient developed by the antiskid system to the maximum drag force friction coefficient available was higher on the dry surface than on damp and flooded surfaces, and was reduced with lighter vertical loads, higher yaw angles, and when new tire treads were replaced by worn treads. Similarly, the average ratio of side force friction coefficient developed by the tire under antiskid control to the maximum side force friction coefficient available to a freely rolling yawed tire decreased with increasing yaw angle, generally increased with ground speed, and decreased when tires with new treads were replaced by those with worn treads.

Tanner, J. A.↗
NASA NTRS1977

Process of forming catalytic surfaces for wet oxidation reactions

A wet oxidation process was developed for oxidizing waste materials, comprising dissolved ruthenium salt in a reactant feed stream containing the waste materials. The feed stream is introduced into a reactor, and the reactor contents are then raised to an elevated temperature to effect deposition of a catalytic surface of ruthenium black on the interior walls of the reactor. The feed stream is then maintained in the reactor for a period of time sufficient to effect at least partial oxidation of the waste materials.

Jagow, R. B.↗
NASA NTRS1976

Energy Conservation Alternatives Study (ECAS): Conceptual Design and Implementation Assessment of a Utility Steam Plant with Conventional Furnace and Wet Lime Stack Gas Scrubbers

A study was performed to estimate the technical/economic characteristics of a steam power plant (3500 pounds per square inch gauge, 1000 degrees Fahrenheit / 1000 degrees Fahrenheit) with a coal-burning radiant furnace and a wet lime stack gas scrubber to control sulfur emissions. Particulate emissions were controlled by an electrostatic precipitator operating at 300 degrees Fahrenheit. The stack gas from the scrubber was reheated from 125 degrees Fahrenheit to 250 degrees Fahrenheit as a base case, and from 125 degrees Fahrenheit to 175 degrees Fahrenheit as an alternate case. The study was performed on a basis consistent with the General Electric ECAS Phase II evaluation of advanced energy conversion systems for electric utility baseload applications using coal or coal-derived fuels. A conceptual design of the power plant was developed, including the on-site calcination of limestone to lime and the provision of sludge ponds to store the products of flue gas scrubbing. From this design, estimates were derived for power plant efficiency, capital cost, environmental intrusion characteristics, natural resource requirements, and cost of electricity at an assumed capacity factor of 65 percent. An implementation assessment was performed where factors affecting applicability of the conceptual design power plant in electric utility generation systems were appraised. At 250 degrees Fahrenheit and 175 degrees Fahrenheit stack gas temperatures respectively, the plants showed a cost of electricity of 39.8 and 37.0 mills per kilowatt-hours and overall plant efficiencies of 32 percent and 34 percent.

Brown, Dale H.↗
NASA NTRS1980

Reaction bonded silicon nitride prepared from wet attrition-milled silicon

Silicon powder wet milled in heptane was dried, compacted into test bar shape, helium-sintered, and then reaction bonded in nitrogen-4 volume percent hydrogen. As-nitrided bend strengths averaged approximately 290 MPa at both room temperature and 1400 C. Fracture initiation appeared to be associated with subsurface flaws in high strength specimens and both subsurface and surface flaws in low strength specimens.

Herball, T. P.↗
NASA NTRS1980

Deburring die-castings by wet vibratory plant

A wet vibratory procedure for the removal of burrs from die castings is described. In this process synthetic abrasive chips and detergent solutions are agitated with the work in such a way as to produce a spiral circulatory movement. Details of various forms of vibrator basin and shapes of abrasive are illustrated. The automation of deburring is illustrated through the application of vibrators of spiral design in combination with transport and drying devices.

Loeschbart, H. M.↗
NASA NTRS1980

Reaction bonded silicon nitride prepared from wet attrition-milled silicon

Silicon powder wet milled in heptane was dried, compacted into test bar shape, helium-sintered, and then reaction bonded in nitrogen-4 vol% hydrogen. As-nitrided bend strengths averaged approximately 290 MPa at both room temperature and 1400 C. Fracture initiation appeared to be associated with subsurface flaws in high-strength specimens and both subsurface and surface flaws in low-strength specimens.

Herbell, T. P.↗
NASA NTRS1981

Wet countdown demonstration and flight readiness firing

The prelaunch tests for the Space Transportation System 1 flight are briefly described. Testing is divided into two major sections: the wet countdown demonstration test/flight readiness firing, which includes a 20 second test firing of the orbiter's three main engines, and a mission verification test, which is centered on flight and landing operations. The functions of the countdown sequence are listed and end of mission and mission abort exercises are described.

Source record↗
NASA NTRS1980

Liquid distribution and the dielectric constant of wet snow

The mixing theory of Polder and Van Santen is revised for application to three cases of wet snow. The dielectric constant is calculated for a range of liquid contents and porosities. These calculated values compare favorably with experimental data for the two cases in which data available. The application to a snow cover with a heterogeneous distribution of liquid is discussed. The possibility of applying this theory the calculate the imaginary part of the dielectric constant must be explored further.

Colbeck, S. C.↗
NASA NTRS1981

Behavior of aircraft antiskid braking systems on dry and wet runway surfaces: Hydromechanically controlled system

The investigation utilized one main gear wheel, brake, and tire assembly of a McDonnell Douglas DC-9 series 10 airplane. The landing-gear strut was replaced by a dynamometer. During maximum braking, average braking behavior indexes based upon brake pressure, brake torque, and drag-force friction coefficient developed by the antiskid system were generally higher on dry surfaces than on wet surfaces. The three braking behavior indexes gave similar results but should not be used interchangeably as a measure of the braking of this antiskid sytem. During the transition from a dry to a flooded surface under heavy braking, the wheel entered into a deep skid but the antiskid system reacted quickly by reducing brake pressure and performed normally during the remainder of the run on the flooded surface. The brake-pressure recovery following transition from a flooded to a dry surface was shown to be a function of the antiskid modulating orifice.

Tanner, J. A.↗
NASA NTRS1981

Wet oxidation as a waste treatment in closed systems

The chemistry of the wet oxidation process has been investigated in relation to production of plant nutrients from plant and human waste materials as required for a closed life-support system. Hydroponically grown lettuce plants were used as a model plant waste and oxygen gas was used as oxidant. Organic nitrogen content was decreased 88-100% depending on feed material. Production of ammonia and nitrogen gas account for all of the observed decrease in organic nitrogen content. No nitrous oxide (N2O) was detected. The implications of these results for closed life-support systems are discussed.

Onisko, B. L.↗
NASA NTRS1982

Wet Oxidation as a Waste Treatment Method in Closed Systems

The chemistry of the wet oxidation process was investigated in relation to production of plant nutrients from plant and human waste materials as required for a closed life support system. Hydroponically grown lettuce plants were used as a model plant waste, and oxygen gas was used as an oxidant. Organic nitrogen content was decreased 88-100%, depending on feed material. Production of ammonia and nitrogen gas accounted for all of the observed decrease in organic nitrogen content. No nitrous oxide (N2O) was detected. The implications of these results for closed life support systems are discussed.

Onisko, B. L.↗
NASA NTRS1985

Inhibiting Wet Oxidation of Ammonia

Simple modification of wet-oxidation process for treating organicwaste reduces loss of fixed nitrogen, potentially valuable byproduct of process. Addition of sufficient sulfuric acid to maintain reaction pH below 3 greatly reduces oxidation of ammonia to free nitrogen. No equipment modification required.

Onisko, D. B. L.↗
NASA NTRS1984

Capillary rise, wetting layers, and critical phenomena in confined geometry

Interferometric procedures have been used to measure the thickness of the wetting layers of liquid SF6 which intrude between SF6 vapor and the walls of an interferometer. Close to the critical temperature the measurements show that the layers become thicker as the height at which they are observed approaches the height of the bulk liquid-vapor meniscus. The functional form of the thickness increase agrees with the dependence expected from models in which the layers' thicknesses are governed by a competition between gravitational and van der Waals forces. The layers are a factor of three thicker than a simple estimate based on such models. No evidence is found of a transition from three-dimensional critical behavior towards two-dimensional critical behavior in the available temperature and size ranges. This contrasts with the interpretation of experiments in binary liquid mixtures carried out with comparable size and temperature resolution.

Moldover, M. R.↗
NASA NTRS1984

Critical point wetting drop tower experiment

Preliminary results for the Critical Point Wetting CPW Drop Tower Experiment are produced with immiscible systems. Much of the observed phenomena conformed to the anticipated behavior. More drops will be needed to test the CPW theory with these immiscible systems.

Kaukler, W. F.↗
NASA NTRS1985

Wetting layers and dispersion forces for a fluid in contact with a vertical wall

Ellipsometric measurements of the thickness of the wetting layer of sulfur hexafluoride that forms on a fused-silica surface partially immersed in the liquid are presented. The components of the experiment included a He-Ne laser (0.6328 micron), polarizer, and quarter-wave plate with 45-deg azimuth. An optical-grade fused-silica prism was polished to wavelength/20, and strain-induced birefringence was accounted for. It was found that the layer thickness decreases from 40 to 20 nm with a height increase from 0.7 to 3 mm above the liquid-vapor interface. The thickness is independent of the temperature between 10 and 0.1 K below the critical temperature (319 K). The results are compared in detail to the theory of Dzyaloshinskii et al. (1961), and are noted to coincide closely.

Kayser, R. F.↗
NASA NTRS1985

Direct Observation of Critical Point Wetting in Microgravity

The objective of this program is to observe the interface shape in single and multicomponent systems at the onset of critical wetting in microgravity using the MSFC drop tower and KC-135 aircraft. Test cells for the drop facility were built and tested up to critical point of CCl. Low temperature drops were conducted for two-component systems near the critical consolute point. Contact angle seems to approach 90 deg near the critical consolute temperature contrary to expectations. It is suspected that since the interfacial energy becomes vanishingly small at the critical consolute temperature, the interface shape has not reached equilibrium in the available low-gravity time.

Kaukler, W. F.↗
NASA NTRS1986

Wet-oxidation waste management system for CELSS

A wet oxidation system will be useful in the Closed Ecological Life Support System (CELSS) as a facility to treat organic wastes and to redistribute inorganic compounds and elements. However at rather higher temperatures needed in this reaction, for instance, at 260 deg C, only 80% of organic in a raw material can be oxidized, and 20% of it will remain in the liquid mainly as acetic acid, which is virtually noncombustible. Furthermore, nitrogen is transformed to ammonium ions which normally cannot be absorbed by plants. To resolve these problems, it becomes necessary to use catalysts. Noble metals such as Ru, Rh and so on have proved to be partially effective as these catalysts. That is, oxidation does not occur completely, and the unexpected denitrification, instead of the expected nitrification, occurs. So, it is essential to develop the catalysts which are able to realize the complete oxidation and the nitrification.

Takahashi, Y.↗
NASA NTRS1985

Wet oxidation of a spacecraft model waste

Wet oxidation was used to oxidize a spacecraft model waste under different oxidation conditions. The variables studied were pressure, temperature, duration of oxidation, and the use of one homogeneous and three heterogeneous catalysts. Emphasis is placed on the final oxidation state of carbon and nitrogen since these are the two major components of the spacecraft model waste and two important plant nutrients.

Johnson, C. C.↗