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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1930

Pressure distribution on the tail surfaces of a PW-9 pursuit airplane in flight

Presented here are pressure distribution data obtained from the tail surfaces of a PW-9 in a number of flight maneuvers. The results given are part of those obtained in an extensive investigation of the pressure distribution over all of the lifting and control surfaces of this airplane. The results are given in tabular and curve form and are discussed briefly with respect to their comparison with existing tail surface design specifications. It is recommended that tail load design loadings should be revised upwards. This is particularly true of leading edge loads, which should be at least doubled for thick sections.

Rhode, Richard V↗
DOE OSTI2014

Controlling the number of graphene sheets exfoliated from graphite by designed normal loading and frictional motion

We use molecular dynamics to study the exfoliation of patterned nanometer-sized graphite under various normal loading conditions for friction-induced exfoliation. Using highly ordered pyrolytic graphite (HOPG) as well as both amorphous and crystalline SiO{sub 2} substrate as example systems, we show that the exfoliation process is attributed to the corrugation of the HOPG surface and the atomistic roughness of the substrate when they contact under normal loading. The critical normal strain, at which the exfoliation occurs, is higher on a crystalline substrate than on an amorphous substrate. This effect is related to the atomistic flatness and stiffness of the crystalline surface. We observe that an increase of the van der Waals interaction between the graphite and the substrate results in a decrease of the critical normal strain for exfoliation. We find that the magnitude of the normal strain can effectively control the number of exfoliated graphene layers. This mechanism suggests a promising approach of applying designed normal loading while sliding to pattern controlled number of graphene layers or other two-dimensional materials on a substrate surface.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Challenges in Rotor Aerodynamic Modeling for Non-Uniform Inflow Conditions

Within an international collaboration framework, the accuracy of rotor aerodynamic models used for design load calculations of wind turbines is being assessed. Where the use of high-fidelity computation fluid dynamics (CFD) and mid-fidelity free-vortex wake (FVW) models has become commonplace within the wind energy community, these still fail to meet the requirements in terms of execution time and computational cost needed for design load calculations. The fast but engineering fidelity blade-element/momentum (BEM) method can therefore still be considered the industry workhorse for design load simulations. At the same time, upscaling of wind turbine rotors makes inflow non-uniformities (e.g. shear, veer, turbulence) more important. The objective of this work is to assess model accuracy in non-uniform inflow conditions, which violate several BEM assumptions. Thereto a comparison in turbulent inflow has been executed including a wide variety of codes, focusing on the DanAero field measurements, where a 2.3-MW turbine was equipped with, among other sensors, a pressure measurement apparatus. The results indicate that, although average load patterns are in good agreement, this does not hold for the unsteady loads that drive fatigue damage and aero-elastic stability. A simplified comparison round in vertical shear was initiated to investigate the observed differences in a more controlled manner. A consistent offset in load amplitude was observed between CFD and free-vortex codes on the one hand and BEM-type codes on the other hand. To shed more light on the observations, dedicated efforts are ongoing to pinpoint the cause for these differences, in the end leading to guidelines for an improved BEM implementation.

17 WIND ENERGY↗
NASA NTRS2007

System and method of designing a load bearing layer of an inflatable vessel

A computer-implemented method is provided for designing a restraint layer of an inflatable vessel. The restraint layer is inflatable from an initial uninflated configuration to an inflated configuration and is constructed from a plurality of interfacing longitudinal straps and hoop straps. The method involves providing computer processing means (e.g., to receive user inputs, perform calculations, and output results) and utilizing this computer processing means to implement a plurality of subsequent design steps. The computer processing means is utilized to input the load requirements of the inflated restraint layer and to specify an inflated configuration of the restraint layer. This includes specifying a desired design gap between pairs of adjacent longitudinal or hoop straps, whereby the adjacent straps interface with a plurality of transversely extending hoop or longitudinal straps at a plurality of intersections. Furthermore, an initial uninflated configuration of the restraint layer that is inflatable to achieve the specified inflated configuration is determined. This includes calculating a manufacturing gap between pairs of adjacent longitudinal or hoop straps that correspond to the specified desired gap in the inflated configuration of the restraint layer.

Spexarth, Gary R.↗
NASA NTRS1997

Evaluation of a Composite Sandwich Fuselage Side Panel with Damage and Subjected to Internal Pressure

The results from an experimental and analytical study of a composite sandwich fuselage side panel for a transport aircraft are presented. The panel has two window cutouts and three frames, and has been evaluated with internal pressure loads that generate biaxial tension loading conditions. Design limit load and design ultimate load tests have been performed on the graphite-epoxy sandwich panel with the middle frame removed to demonstrate the suitability of this two-frame design for supporting the prescribed biaxial loading conditions with twice the initial frame spacing of 20 inches. The two-frame panel was damaged by cutting a notch that originates at the edge of a cutout and extends in the panel hoop direction through the window-belt area. This panel with a notch was tested in a combined-load condition to demonstrate the structural damage tolerance at the design limit load condition. The two panel configurations successfully satisfied all design load requirements in the experimental part of the study, and the three-frame and two-frame panel responses are fully explained by the analysis results. The results of this study suggest that there is potential for using sandwich structural concepts with greater than the usual 20-in.-wide frame spacing to further reduce aircraft fuselage structural weight.

Rouse, Marshall↗
DOE OSTI2015

Analyzing Design Heating Loads in Superinsulated Buildings

The U.S. Department of Energy’s Building America research team Consortium for Advanced Residential Buildings (CARB) worked with the EcoVillage cohousing community in Ithaca, New York, on the Third Residential EcoVillage Experience neighborhood. This communityscale project consists of 40 housing units—15 apartments and 25 single-family residences. Units range in size from 450 ft2 to 1,664 ft2 and cost from $80,000 for a studio apartment to $235,000 for a three- or four-bedroom single-family home. For the research component of this project, CARB analyzed current heating system sizing methods for superinsulated homes in cold climates to determine if changes in building load calculation methodology should be recommended. Actual heating energy use was monitored and compared to results from the Air Conditioning Contractors of America’s Manual J8 (MJ8) and the Passive House Planning Package software. Results from that research indicate that MJ8 significantly oversizes heating systems for superinsulated homes and that thermal inertia and internal gains should be considered for more accurate load calculations.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1986

Unsteady aerodynamic load estimates on turning vanes in the national full-scale aerodynamic complex

Unsteady aerodynamic design loads have been estimated for each of the vane sets in the National Full-Scale Aerodynamic Complex (NFAC). These loads include estimates of local loads over one vane section and global loads over an entire vane set. The analytical methods and computer programs used to estimate these loads are discussed. In addition, the important computer input parameters are defined and the rationale used to estimate them is discussed. Finally, numerical values are presented for both the computer input parameters and the calculated design loads for each vane set.

Norman, Thomas R.↗
NASA NTRS1981

System analysis approach to deriving design criteria (Loads) for Space Shuttle and its payloads. Volume 2: Typical examples

The achievement of an optimized design from the system standpoint under the low cost, high risk constraints of the present day environment was analyzed. Space Shuttle illustrates the requirement for an analysis approach that considers all major disciplines (coupling between structures control, propulsion, thermal, aeroelastic, and performance), simultaneously. The Space Shuttle and certain payloads, Space Telescope and Spacelab, are examined. The requirements for system analysis approaches and criteria, including dynamic modeling requirements, test requirements, control requirements, and the resulting design verification approaches are illustrated. A survey of the problem, potential approaches available as solutions, implications for future systems, and projected technology development areas are addressed.

Ryan, R. S.↗
NASA NTRS1981

The nature of operating flight loads and their effect on propulsion system structures

Past diagnostics studies revealed the primary causes of performance deterioration of high by-pass turbofan engines to be flight loads, erosion, and thermal distortion. The various types of airplane loads that are imposed on the engine throughout the lifetime of an airplane are examined. These include flight loads from gusts and maneuvers and ground loads from takeoff, landing, and taxi conditions. Clarification is made in definitions of the airframer's limit and ultimate design loads and the engine manufacturer's operating design loads. Finally, the influence of these loads on the propulsion system structures is discussed.

Dickenson, K. H.↗
NASA NTRS1978

Module/array interface study

Several aspects of module design are evaluated, including glass superstrate and metal substrate module configurations, the potential for hail damage, light absorption in glass superstrates, the economics of glass selection, and electrical design. Also, three alternate glass superstrate module configurations are evaluated by means of finite element computer analyses. Two panel sizes, 1.2 by 2.4 m (4 by 8 ft) and 2.4 by 4.8 m are used to support three module sizes, 0.6 by 1.2 m, 1.2 by 1.2 m, and 1.2 by 2.4 m, for design loadings of + or - 1.7 kPa, + or - 2.4 kPa, and + or - 3.6 kPa. Designs and cost estimates are presented for twenty panel types and nine array configurations at each of the three design loadings. Structural cost sensitivities of combined array configurations and panel cases are presented.

Source record↗
NASA NTRS1985

Dynamic verification of very large space structures

The dynamic verification of spacecraft relies heavily on ground-based tests. These tests usually simulate flight environments or validate analytical models used in establishing design loads and in designing control algorithms. They also provide security against failures resulting from unanticipated or unmodeled hardware behavior. Future orbital antennas, space stations, and solar power systems are likely to be of sizes difficult to test using current ground test technology. In addition to size, other factors such as low natural frequencies, lightweight construction, and the presence of many structural joints, cause significant sensitivity of the test process to the earth-gravity environment. Yet, accuracy requirements on the verification process will be more stringent because of modern flexible-structure control approaches. This paper describes some of the problems and discusses research on potential solutions. The importance of an integrated ground test, analysis, and flight test program is emphasized. An ongoing research program of this type focusing on a 60-meter, deployable, truss-beam test article is described.

Hanks, B. R.↗
DOE OSTI2015

Analyzing Design Heating Loads in Superinsulated Buildings

Super-insulated homes offer many benefits including improved comfort, reduced exterior noise penetration, lower energy bills, and the ability to withstand power and fuel outages under much more comfortable conditions than a typical home. While these homes aren't necessarily constructed with excessive mass in the form of concrete floors and walls, the amount of insulation and the increase in the thickness of the building envelope can lead to a mass effect, resulting in the structures ability to store much more heat than a code built home. This results in a very low thermal inertia making the building much less sensitive to drastic temperature swings thereby decreasing the peak heating load demand. During the winter of 2013/2014, CARB monitored the energy use of three homes in climate zone 6 in an attempt to evaluate the accuracy of two different mechanical system sizing methods for low load homes. Based on the results, it is recommended that internal and solar gains be included and some credit for thermal inertia be used in sizing calculations for super insulated homes.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1995

Axisymmetric inlet minimum weight design method

An analytical method for determining the minimum weight design of an axisymmetric supersonic inlet has been developed. The goal of this method development project was to improve the ability to predict the weight of high-speed inlets in conceptual and preliminary design. The initial model was developed using information that was available from inlet conceptual design tools (e.g., the inlet internal and external geometries and pressure distributions). Stiffened shell construction was assumed. Mass properties were computed by analyzing a parametric cubic curve representation of the inlet geometry. Design loads and stresses were developed at analysis stations along the length of the inlet. The equivalent minimum structural thicknesses for both shell and frame structures required to support the maximum loads produced by various load conditions were then determined. Preliminary results indicated that inlet hammershock pressures produced the critical design load condition for a significant portion of the inlet. By improving the accuracy of inlet weight predictions, the method will improve the fidelity of propulsion and vehicle design studies and increase the accuracy of weight versus cost studies.

Nadell, Shari-Beth↗
NASA NTRS2010

System and method of designing a load bearing layer that interfaces to a structural pass-through of an inflatable vessel

A method for determining a design of an inflatable module including a rigid member disposed in a restraint layer, wherein the restraint layer includes orthogonal straps, includes modeling a strap adjacent to the rigid member and a strap connected to the rigid member. The adjacent strap and the member strap extend in a first direction. The method further includes selecting a first length of the member strap such that the adjacent strap carries load before the member strap during pressurization of the inflatable module, modeling tensions in the member strap with the first length and the adjacent strap during pressurization of the inflatable model, and outputting the modeled tensions in the member strap with the first length and the adjacent strap. An inflatable module includes a member strap having a length such that an adjacent strap carries load before the member strap during pressurization of the inflatable module.

Spexarth, Gary R.↗
NASA NTRS1998

Response of Composite Fuselage Sandwich Side Panels Subjected to Internal Pressure and Axial Tension

The results from an experimental and analytical study of two composite sandwich fuselage side panels for a transport aircraft are presented. Each panel has two window cutouts and three frames and utilizes a distinctly different structural concept. These panels have been evaluated with internal pressure loads that generate biaxial tension loading conditions. Design limit load and design ultimate load tests have been performed on both panels. One of the sandwich panels was tested with the middle frame removed to demonstrate the suitability of this two-frame design for supporting the prescribed biaxial loading conditions with twice the initial frame spacing of 20 inches. A damage tolerance study was conducted on the two-frame panel by cutting a notch in the panel that originates at the edge of a cutout and extends in the panel hoop direction through the window-belt area. This panel with a notch was tested in a combined-load condition to demonstrate the structural damage tolerance at the design limit load condition. Both the sandwich panel designs successfully satisfied all desired load requirements in the experimental part of the study, and experimental results from the two-frame panel with and without damage are fully explained by the analytical results. The results of this study suggest that there is potential for using sandwich structural concepts with greater than the usual 20-in. wide frame spacing to further reduce aircraft fuselage structural weight.

Rouse, Marshall↗
DOE OSTI2015

Technology Solutions Case Study: Low-Load Space-Conditioning Needs Assessment

Low-load options in the heating, ventilating, and air-conditioning (HVAC) market are limited, so many new-construction housing units are being fitted with oversized equipment that results in penalties in system efficiency, comfort, and cost. To bridge the gap between currently available HVAC equipment and the rising demand for low-load HVAC equipment in the marketplace, HVAC equipment manufacturers need to be fully aware of the needs of the multifamily building and attached single-family home markets. Over the past decade, Steven Winter Associates, Inc. has provided certification and consulting services for hundreds of housing projects and has accrued a large pool of data that describe multifamily and attached single-family home characteristics. In this project, the research team Consortium for Advanced Residential Buildings (CARB) compiled and analyzed the data from 941 low-load buildings in the Northeast and Mid-Atlantic regions to outline the heating and cooling design load characteristics of low-load dwellings. Within this data set, CARB found that only 1% of the dwellings had right-sized (within 25% of design load) heating equipment and 6% had right-sized cooling equipment.

Air-source heat pumps↗
NASA NTRS1981

System analysis approach to deriving design criteria (loads) for Space Shuttle and its payloads. Volume 1: General statement of approach

Space shuttle, the most complex transportation system designed to date, illustrates the requirement for an analysis approach that considers all major disciplines simultaneously. Its unique cross coupling and high sensitivity to aerodynamic uncertainties and high performance requirements dictated a less conservative approach than those taken in programs. Analyses performed for the space shuttle and certain payloads, Space Telescope and Spacelab, are used a examples. These illustrate the requirements for system analysis approaches and criteria, including dynamic modeling requirements, test requirements control requirements and the resulting design verification approaches. A survey of the problem, potential approaches available as solutions, implications for future systems, and projected technology development areas are addressed.

Ryan, R. S.↗