Hydrodynamic Simulations and the Vapor Dome
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Determination of minimum weight shape and stiffening configuration for doubly curved shells subjected to external buckling pressures
Fabrication techniques of bulkheads for Saturn upper stages
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Structural analysis of glass filament wound, aluminum lined pressure vessel designs
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A procedure is presented that permits determination of the shape of the gravity field due to an arbitrary mass configuration with circular symmetry. The procedure is used to model the shape of the field associated with the lunar circular basins. The mean slopes of the equipotential surfaces generated by a superisostatic deposit corresponding to a near-surface Crisium-size mascon are calculated to fall within the range from 1:700 to 1:1000; those generated by a mantle rebound of the same excess mass, at 60 km below the lunar surface, cluster around the value of 1:1500.
The technical and economic advantages of using air-supported plastic enclosures to protect flat plate photovoltaic arrays are described. Conceptual designs for a fixed, latitude-tilt array and a fully tracking array were defined. Detailed wind loads and strength analyses were performed for the fixed array. Detailed thermal and power output analyses provided array performance for typical seasonal and extreme temperature conditions. Costs of each design as used in a 200 MWe central power station were defined from manufacturing and material cost estimates. The capital cost and cost of energy for the enclosed fixed-tilt array were lower than for the enclosed tracking array. The enclosed fixed-tilt array capital investment was 38% less, and the levelized bus bar energy cost was 26% less than costs for a conventional, glass-encapsulated array design. The predicted energy cost for the enclosed fixed array was 79 mills/kW-h for direct current delivered to the power conditioning units.
In performing the data analysis of the measurements achieved during the Workshop with the device, a global approach was preferred rather than an individual analysis, in order to illustrate some main characteristics in the behavior of the device with respect to a mean behavior resulting from a general survey of all the equipments involved in each experiment. The device tends generally to overestimate the CCN concentrations measured near the high supersaturations and sometimes underestimates the concentrations close to 0.1% or 0.2% of supersaturation. Despite the fact that it belongs to a type of static diffusion chamber, it shows, however, similar spectra to those obtained with other types of chambers (continuous flow diffusion chamber and haze chamber).
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The purpose of this investigation was to determine the geologic history of Picacho Butte and vicinity through careful mapping of a 38 square kilometer area surrounding the peak. A detailed analysis of the geochemistry and petrology will aid in the development of a petrogenetic model for the area. The relationship of Picacho Butte to regional volcanism in Arizona, and more specifically to nearby volcanic centers can thus be established. Furthermore, in conjunction with this study a search will be made for possible planetary analogs exhibiting photogeologic characteristics similar to those in northern Arizona.
Aerothermal tests were conducted in the NASA Langley 8 Foot High Temperature Tunnel (8'HTT) at a Mach number of 6.5 on simulated arrays of thermally bowed metallic thermal protection system (TPS) tiles at an angle of attack of 5 deg. Detailed surface pressures and heating rates were obtained for arrays aligned with the flow and skewed 45 deg diagonally to the flow with nominal bowed heights of 0.1, 0.2, and 0.4 inch submerged in both laminar and turbulent boundary layers. Aerothermal tests were made at a nominal total temperature of 3300 R, a total pressure of 400 psia, a total enthalpy of 950 Btu/lbm, a dynamic pressure of 2.7 psi, and a unit Reynolds number of 400,000 per foot. The experimental results form a data base that can be used to help protect aerothermal load increases from bowed arrays of TPS tiles.
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NASA Lewis and ENTECH have been developing a high-efficiency, lightweight space photovoltaic concentrator array. The emphasis of the program has shifted to fabrication and testing of the minidome Fresnel lens and other array components. Protototype lenses have been tested for optical efficiency, with results around 90 percent, and tracking error performance. The results of these tests have been very consistent with the predicted analytical performance. Work has also progressed in the fabrication of the array support structure. Recent advances in 30 percent efficient stacked cell technology will have a significant effect on the array performance. It is concluded that near-term array performance goals of 300 W/sq m and 100 W/kg are feasible.
A high-efficiency, lightweight space photovoltaic concentrator array is described. Previous work on the minidome Fresnel lens concentrator concept is being integrated with Boeing's 30 percent efficient tandem GaAs/GaSb concentrator cells into a high-performance photovoltaic array. Calculations indicate that, in the near term, such an array can achieve 300 W/sq m at a specific power of 100 W/kg. Emphasis of the program has now shifted to integrating the concentrator lens, tandem cell, and supporting panel structure into a space-qualifiable array. A description is presented of the current status of component and prototype panel testing and the development of a flight panel for the Photovoltaic Array Space Power Plus Diagnostics (PASP PLUS) flight experiment.