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At least 91 records · Page 5

All sources NASA NTRS DOE OSTI

NASA NTRS1977

Thermal barrier coating on high temperature industrial gas turbine engines

The thermal barrier coating used was a yttria stabilized zirconia material with a NiCrAlY undercoat, and the base engine used to establish improvements was the P&WA FT50A-4 industrial gas turbine engine. The design benefits of thermal barrier coatings include simplified cooling schemes and the use of conventional alloys in the engine hot section. Cooling flow reductions and improved heating rates achieved with thermal barrier coating result in improved performance. Economic benefits include reduced power production costs and reduced fuel consumption. Over the 30,000 hour life of the thermal barrier coated parts, fuel savings equivalent to $5 million are projected and specific power (megawatts/mass of engine airflow) improvements on the order of 13% are estimated.

Carlson, N.↗

NASA NTRS1978

The application of photovoltaic roof shingles to residential and commercial buildings

The recent development of a shingle-type solar-cell module makes it possible to incorporate easily photovoltaic power generation into the sloping roofs of residential or commercial buildings. These modules, which use a closely packed array of nineteen 53-mm-diameter circular solar cells, are capable of producing 101 watts/sq m of module area under standard operating conditions. This module performance is achievable by the use of solar cells with an average efficiency of 13.3 percent at 1 kW/sq m air-mass-1.5 insolation and at a cell temperature of 28 C. When these modules are mounted on a sloping south-facing roof which is insulated on the rear surface, the annual energy generated at the maximum power operating point will vary from 255.6 to 137.3 kWh/sq m of module area depending on the site location, with Albuquerque, NM, and Seattle, WA, representing the highest and lowest values of the thirteen sites considered.

Shepard, N. F., Jr.↗

NASA NTRS1981

Beat frequency interference pattern characteristics study

The frequency spectra and corresponding beat frequencies created by the relative motions between multiple Solar Power Satellites due to solar wind, lunar gravity, etc. were analyzed. The results were derived mathematically and verified through computer simulation. Frequency spectra plots were computer generated. Detailed computations were made for the seven following locations in the continental US: Houston, Tx.; Seattle, Wa.; Miami, Fl.; Chicago, Il.; New York, NY; Los Angeles, Ca.; and Barberton, Oh.

Ott, J. H.↗

NASA NTRS1981

A study to define the research and technology requirements for advanced turbo/propfan transport aircraft

The feasibility of the propfan relative to the turbofan is summarized, using the Douglas DC-9 Super 80 (DS-8000) as the actual operational base aircraft. The 155 passenger economy class aircraft (31,775 lb 14,413 kg payload), cruise Mach at 0.80 at 31,000 ft (8,450 m) initial altitude, and an operational capability in 1985 was considered. Three propfan arrangements, wing mounted, conventional horizontal tail aft mounted, and aft fuselage pylon mounted are selected for comparison with the DC-9 Super 80 P&WA JT8D-209 turbofan powered aircraft. The configuration feasibility, aerodynamics, propulsion, structural loads, structural dynamics, sonic fatigue, acoustics, weight maintainability, performance, rough order of magnitude economics, and airline coordination are examined. The effects of alternate cruise Mach number, mission stage lengths, and propfan design characteristics are considered. Recommendations for further study, ground testing, and flight testing are included.

Goldsmith, I. M.↗

NASA NTRS1982

Observation of a heated electron population associated with the 6300 A SAR arc emission

Conjunctive observations of the Dynamics Explorer satellite pair and the Pacific Northwest Laboratory scanning photometer unit at Richland, WA have allowed identification of the low energy, heated, electron population associated with the 6300 A Stable Auroral Red (SAR) arc emission. Measurements over the SAR arc on day 296 of 1981 show an enhanced flux in the low altitude 5-12 eV electrons. Analysis of this electron population shows them to be fairly Maxwellian, with temperatures on the order of 9900 + or - 1100 K and an earthward field aligned velocity of approximately 275 + or - 60 km/sec. The electrons are not accompanied by ion precipitation. The ion loss cone is empty at least as high as 6000 km. This fact may cast some doubt as to the role of the ring current ions in the SAR arc production.

Gurgiolo, C.↗

NASA NTRS1982

Characteristics of a stable auroral red arc event

The present investigation is concerned with an analysis of the measurements of the stable auroral red (SAR) arc of October 23, 1981, using data from orbit 1192 of Dynamics Explorer (DE) 2, during which a magnetic coincidence occurred with the DE-1 spacecraft near the red arc field line, and for which simultaneous ground-based intensity measurements from Richland, WA were available. The altitude of the DE-2 satellite was approximately 850 km during arc passage in the Northern Hemisphere and approximately 395 km during the conjugate hemisphere passage. The DE-1 satellite was at an altitude of approximately 6000 km during the magnetic coincidence with DE-2 in the Northern Hemisphere. The described observations and calculations reconfirm a previous understanding that the actual excitation of the O(1D) state responsible for the 6300 A emission of red arcs is caused by hot ionospheric thermal electrons.

Kozyra, J. U.↗

NASA NTRS1983

Progress toward determining the potential of ODS alloys for gas turbine applications

The Materials for Advanced Turbine Engine (MATE) Program managed by the NASA Lewis Research Center is supporting two projects to evaluate the potential of oxide dispersion strengthened (ODS) alloys for aircraft gas turbine applications. One project involves the evaluation of Incoloy (TM) MA-956 for application as a combustor liner material. An assessment of advanced engine potential will be conducted by means of a test in a P&WA 2037 turbofan engine. The other project involves the evaluation of Inconel (TM) MA 6000 for application as a high pressure turbine blade material and includes a test in a Garrett TFE 731 turbofan engine. Both projects are progressing toward these engine tests in 1984.

Dreshfield, R. L.↗

NASA NTRS1984

Planetary geomorphology field studies: Washington and Alaska

Field studies of terrestrial landforms and the processes that shape them provide new directions to the study of planetary features. Investigations discussed address principally mudflow phenomena and drainage development. At the Valley of 10,000 Smokes (Katmai, AK) and Mount St. Helens, WA, studies of the development of erosional landforms (in particular, drainage) on fresh, new surfaces permitted analysis of the result of competition between geomorphic processes. Of specific interest is the development of stream pattern as a function of the competition between perennial seepage overland flow (from glacial or groundwater sources), ephemeral overland flow (from pluvial or seasonal melt sources), and ephemeral/perennial groundwater sapping, as a function of time since initial resurfacing, material properties, and seasonal/annual environmental conditions.

Malin, M. C.↗

NASA NTRS1983

Halocarbon concentration patterns associated with frontal passages

The atmospheric mixing ratios of CCl2F2 (F-12) and CCl3F (F-11) increase abruptly up to 14 ppt (F-12) and 8 ppt (F-11) after strong cold fronts pass and decrease abruptly after warm fronts pass at a semicontinuous monitoring station near Pullman, WA (46 deg 42 min N, 117 deg 10 min W). It is concluded that air masses from higher latitudes (above 60 deg N) can have F-12 and/or F-11 concentrations as much as 5 percent higher than mid-latitude air masses. Conversely, nitrous oxide shows no significant changes during frontal passages and is uniformly distributed between air masses.

Carter, M. W.↗

NASA NTRS1983

Study of controlled diffusion stator blading

Tests were conducted on a high tip speed, highly loaded front compressor stage having low aspect ratio rotor and stator airfoils. The stator airfoils were designed by the controlled diffusion procedure recently developed by P&WA for designing transonic cascade airfoils. The rotor blades consisted of multiple-circular-arc airfoil sections. The stage had a tip speed of 442 m/sec (1450 ft/sec), a hub/tip ratio of 0.597, a rotor aspect ratio of 1.3, and a stator aspect ratio of 1.45. At design speed the rotor-stator stage achieved an adiabatic efficiency of 89.1% at design flow and pressure ratio. Surge margin was 14%. The stage efficiency exceeded the design goal by 0.6 percentage points. The rotor efficiency was 92.4%, exceeding design by 0.3 percentage points. The controlled diffusion stator demonstrated a lower minimum loss over the multiple-circular-arc stator from the root to 70 percent span. A surge diffusion factor of 0.72 was reached at both the rotor tip and the stator root. The NAS3-22008 program demonstrated its intent: high efficiency and loading levels with low aspect ratio blades and the controlled diffusion stator in the unfavorable front stage environment.

Behlke, R. F.↗

NASA NTRS1984

Mod-2 wind turbine field operations experience

The Mod-2 wind turbine is now in a 2-year research/experimental operations phase which offers a unique opportunity to study the effects of single and multiple wind turbines interacting with each other, the power grid, and the environment. This paper addresses the field operations and research testing experienced at the Mod-2 Cluster Goodnoe Hills Research Test Site near Goldendale, WA. Field operation, both routine and nonroutine, are discussed as well as the role of the participating utility. Technical areas discussed pertain to system performance and loads. Specific research tests relating to acoustics, TV interference, and wake effects are also discussed.

Gordon, L. H.↗

NASA NTRS1986

Astrometric observations of comets and asteroids and subsequent orbital investigations

During the past year some 500 observations were made on 66 nights and published on the MPCs (Minor Planet Circulars/Minor Planets and Comets). In addition, a handful of measurements of earlier plates were completed and published. 121 of the observations published referred to comets. Of special importance were observations of comets (P/Giacobini-Zinner and P/Halley) in connection with the NASA ICE and ESA Giotto missions, but a special effort was made to get good coverage of almost all of the observable comets. Observations were also made of (2060) Chiron and of the earth-approaching objects (1627) Ivar, (1866) Sisyphys, (1943) Anteros, (3362) 1984 QA, 1985 JA, PA, TB and WA, and 1986 DA and EB. 46 minor planets were given permanent numbers entirely as a result of the observations.

Mccrosky, R. E.↗

NASA NTRS1989

Comparison of conceptual designs for 25 kWe advanced Stirling conversion systems for dish electric application

The Advanced Stirling Conversion System (ASCS) Project is managed by NASA Lewis Research Center through a cooperative interagency agreement with DOE. Conceptual designs for the ASCS's were completed under parallel contracts in 1987 by Mechanical Technology Inc. (MTI) of Latham, NY, and Stirling Technology Company (STC) of Richland, WA. Each design features a free-piston Stirling engine, a liquid metal heat pipe receiver, and a means to provide about 25 kW of electric power to a utility grid while meeting DOE's long term performance and cost goals. An independent assessment showed that both designs are manufacturable and have the potential to easily meet DOE's long term cost goals.

Shaltens, Richard K.↗

NASA NTRS1989

Comparison of conceptual designs for 25 kWe advanced Stirling conversion systems for dish electric applications

Shaltens, Richard K.↗

NASA NTRS1992

Low power arcjet test facility impacts

Performance characterization of a flight-type 1.4 kW arcjet system were conducted at the Rocket Research Company (RRC) in Redmond, WA, and at the NASA LeRC in Cleveland, OH. The objectives of these tests were as follows: to compare low-power arcjet performance at two different test facilities; to compare arcjet performance obtained with a 2:1 mixture of gaseous hydrogen and nitrogen and hydrazine; and to quantify the effects of test cell pressure on thruster operating characteristics. Performance and thruster temperature distributions were measured at thruster input power levels and propellant mass flow rates ranging from 1274 to 1370 W and from 3.2 x 10(exp -5) to 5.1 x 10(exp -5) kg/s, respectively. Specific impulses measured at the two facilities, at comparable test cell pressures, using gaseous hydrogen-nitrogen propellant mixtures agreed to within 1 percent over the range of operating conditions tested. The specific impulses measured using hydrazine propellant were higher than that for the cold hydrogen-nitrogen mixtures. Agreement between by hydrazine and gas mixture data was good, however, when the differences in propellant enthalpies at the thruster inlet were considered. Specific impulse showed a strong dependence on test facility pressure, and was 3 to 4 percent higher below 0.1 Pa than for test cell pressures above 5 Pa.

Morren, W. Earl↗

NASA NTRS1993

The use of a vegetation index for assessment of the urban heat island effect

A vegetation index and radiative surface temperature were derived from NOAA-11 Advanced Very High Resolution Radiometer (AVHRR) data for the Seattle, WA region from 28 June through 4 July 1991. The vegetation index and surface temperature values were computed for locations of weather observation stations within the region and compared to observed minimum air temperatures. These comparisons were used to evaluate the use of AVHRR data to assess the influence of the urban environment on observed minimum air temperatures (the urban heat island effect). AVHRR derived normalized difference vegetation index (NDVI) and radiant surface temperature data from a one week composite product were both related significantly to observed minimum temperatures, however, the vegetation index accounted for a greater amount of the spatial variation observed in mean minimum temperatures. The difference in the NDVI between urban and rural regions appears to be an indicator of the difference in surface properties (i.e., evaporation and heat storage capacity) between the two environments that are responsible for differences in urban and rural minimum temperatures.

Gallo, K. P.↗

NASA NTRS1931

The variation in pressure in the cabin of an airplane in flight

The pressure in the cabin of a Fairchild cabin monoplane wa surveyed in flight, and was found to decrease with increased air speed over the fuselage and to vary with the number and location of openings in the cabin. The maximum depression of 2.2 inches of water (equivalent pressure altitude at sea level of 152 feet) occurred at the high speed of the airplane in level flight with the cabin closed.

Gough, Melvin N↗

NASA NTRS1994

Second International Symposium on Magnetic Suspension Technology, part 2

In order to examine the state of technology of all areas of magnetic suspension and to review related recent developments in sensors and controls approaches, superconducting magnet technology, and design/implementation practices, the 2nd International Symposium on Magnetic Suspension Technology was held at the Westin Hotel in Seattle, WA, on 11-13 Aug. 1993. The symposium included 18 technical sessions in which 44 papers were presented. The technical sessions covered the areas of bearings, bearing modelling, controls, vibration isolation, micromachines, superconductivity, wind tunnel magnetic suspension systems, magnetically levitated trains (MAGLEV), rotating machinery and energy storage, and applications. A list of attendees appears at the end of the document.

Groom, Nelson J.↗