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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 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Preliminary results of the first static calibration of the RSRA helicopter active-isolator rotor balance system

The helicopter version of the Rotor Systems Research Aircraft (RSRA) is designed to make simultaneous measurements of all rotor forces and moments in flight analogous to a wind tunnel balance. Loads are measured by a combination of load cells, strain gages, and hydropneumatic active isolators which use pressure gages to measure loads. Complete evaluation of system performance required calibration of the rotor force and moment measuring system when installed in the aircraft. Measurement system responses to rotor loads obtained during the first static calibration of the RSRA helicopter are plotted and discussed. Plots of the raw transducer data are included.

Acree, C. W., Jr.↗
NASA NTRS1984

Acoustic measurements of a full-scale rotor with four tip shapes. Volume 2: Appendices C, D, E and F

A full scale helicopter with four different blade tip geometries is tested in a 40- by 80-foot wind tunnel. Performance, loads, and noise are measured. The four tip shapes tested were rectangular, tapered, swept, and swept/tapered. The noise data include measurements of the sound pressure levels in decibels dB, decibels adjusted dBA, and tone-corrected PNdB, for all of the conditions tested. Also included are the detailed measurements, 1/3 octave spectra and time histories for some selected data, and plots of dBA as function of test condition. Some performance measurements are included to aid interpretation of the noise data.

Mosher, M.↗
NASA NTRS1985

Numerical analysis of the first static calibration of the RSRA helicopter active-isolator rotor balance system

The helicopter version of the Rotor Systems Research Aircraft (RSRA) is designed to make simultaneous measurements of all rotor forces and moments in a manner analogous to a wind-tunnel balance. Loads are measured by a combination of load cells, strain gages, and hydropneumatic active isolators with built-in pressure gages. Complete evaluation of system performance requires calibration of the rotor force- and moment-measurement system when installed in the aircraft. Derivations of calibration corrections for various combinations of calibration data are discussed.

Acree, C. W., Jr.↗
NASA NTRS1985

Design Procedure for the New 70-meter Antenna Subreflector Positioner

Design procedures are developed for determining Cassegrain type antenna subreflector positioner strength and displacements under wind and gravity loading conditions. The procedures are applied to the JPL 70-m antenna subreflector design, and the resulting design details are presented. The generalized analysis can be adapted to other antenna and subreflector-positioners. It is shown that the new design meets the strength and displacements criteria under worst case loading.

Hughes, R. D.↗
NASA NTRS1986

Ion distribution functions in the vicinity of Comet Giacobini-Zinner

Photoionization of neutral molecules in the coma surrounding a comet produces heavy ions which contaminate and mass-load the solar wind. Cometary ion distribution functions in the vicinity of Comet Giacobini-Zinner (GZ) are calculated using a Monte Carlo method. The distribution function calculated behind the shock has both cold (approximately 2 keV) and hot (approximately 40 keV) components.

Cravens, T. E.↗
NASA NTRS1991

Analyzing Large Reflector Antenna Structures

Iterative Design of Antenna Structures (IDEAS) computer program performs finite-element analysis and optimization of design, with special features for analysis and design of microwave antennas and associated structural components. Primary feature to perform root-mean-square-best-fitting path-length-error and boresight-pointing-error analyses for Cassegrain microwave antenna structure loaded by gravity, wind, or other environmental effects. Flexible and easy to use. Written in ATHENA FORTRAN and ASSEMBLER.

Levy, Roy↗
NASA NTRS1992

Moessbauer Spectroscopy for Lunar Resource Assessment: Measurement of Mineralogy and Soil Maturity

First-order assessment of lunar soil as a resource includes measurement of its mineralogy and maturity. Soils in which the mineral ilmenite is present in high concentrations are desirable feedstock for the production of oxygen at a lunar base. The maturity of lunar soils is a measure of their relative residence time in the upper 1 mm of the lunar surface. Increasing maturity implies increasing load of solar wind species (e.g., N, H, and He-3), decreasing mean grain size, and increasing glass content. All these physicochemical properties that vary in a regular way with maturity are important parameters for assessing lunar soil as a resource. For example, He-3 can be extracted and potentially used for nuclear fusion. A commonly used index for lunar soil maturity is I(sub s)/FeO, which is the concentration of fine-grained metal determined by ferromagnetic resonance (I(sub s)) normalized to the total iron content (as FeO). I(sub s)/FeO has been measured for virtually every soil returned by the Apollo and Luna missions to the Moon. Because the technique is sensitive to both oxidation state and mineralogy, iron Moessbauer spectroscopy (FeMS) is a viable technique for in situ lunar resource assessment. Its utility for mineralogy is apparent from examination of published FeMS data for lunar samples. From the data published, it can be inferred that FeMS data can also be used to determine soil maturity. The use of FeMS to determine mineralogy and maturity and progress on development of a FeMS instrument for lunar surface use are discussed.

Morris, R. V.↗
NASA NTRS2002

Videogrammetric Model Deformation Measurement System User's Manual

The purpose of this manual is to provide the user of the NASA VMD system, running the MDef software, Version 1.10, all information required to operate the system. The NASA Videogrammetric Model Deformation system consists of an automated videogrammetric technique used to measure the change in wing twist and bending under aerodynamic load in a wind tunnel. The basic instrumentation consists of a single CCD video camera and a frame grabber interfaced to a computer. The technique is based upon a single view photogrammetric determination of two-dimensional coordinates of wing targets with fixed (and known) third dimensional coordinate, namely the span-wise location. The major consideration in the development of the measurement system was that productivity must not be appreciably reduced.

Dismond, Harriett R.↗
NASA NTRS1996

Automated Wing Twist And Bending Measurements Under Aerodynamic Load

An automated system to measure the change in wing twist and bending under aerodynamic load in a wind tunnel is described. The basic instrumentation consists of a single CCD video camera and a frame grabber interfaced to a computer. The technique is based upon a single view photogrammetric determination of two dimensional coordinates of wing targets with a fixed (and known) third dimensional coordinate, namely the spanwise location. The measurement technique has been used successfully at the National Transonic Facility, the Transonic Dynamics Tunnel, and the Unitary Plan Wind Tunnel at NASA Langley Research Center. The advantages and limitations (including targeting) of the technique are discussed. A major consideration in the development was that use of the technique must not appreciably reduce wind tunnel productivity.

Burner, A. W.↗
NASA NTRS2017

Overview: Performance Adaptive Aeroelastic Wing

An overview of recent aeroelasitc wing-shaping work at the NASA Ames Research Center is presented. The highlight focuses on activity related to the Performance Adaptive Aeroelastic Wing concept and related Variable Camber Continuous Trailing Edge Flap actuation system. Topics covered include drag-reducing configurations and online algorithms, gust and maneuver load techniques, and wind tunnel demonstrations.

Hashemi, Kelley↗
DOE OSTI2013

New Structural-Dynamics Module for Offshore Multimember Substructures within the Wind Turbine Computer-Aided Engineering Tool FAST: Preprint

FAST, developed by the National Renewable Energy Laboratory (NREL), is a computer-aided engineering (CAE) tool for aero-hydro-servo-elastic analysis of land-based and offshore wind turbines. This paper discusses recent upgrades made to FAST to enable loads simulations of offshore wind turbines with fixed-bottom, multimember support structures (e.g., jackets and tripods, which are commonly used in transitional-depth waters). The main theory and strategies for the implementation of the multimember substructure dynamics module (SubDyn) within the new FAST modularization framework are introduced. SubDyn relies on two main engineering schematizations: 1) a linear frame finite-element beam (LFEB) model and 2) a dynamics system reduction via Craig-Bampton's method. A jacket support structure and an offshore system consisting of a turbine atop a jacket substructure were simulated to test the SubDyn module and to preliminarily assess results against results from a commercial finite-element code.

17 WIND ENERGY↗
DOE OSTI2014

Assessment and Optimization of Lidar Measurement Availability for Wind Turbine Control: Preprint

Turbine-mounted lidars provide preview measurements of the incoming wind field. By reducing loads on critical components and increasing the potential power extracted from the wind, the performance of wind turbine controllers can be improved [2]. As a result, integrating a light detection and ranging (lidar) system has the potential to lower the cost of wind energy. This paper presents an evaluation of turbine-mounted lidar availability. Availability is a metric which measures the proportion of time the lidar is producing controller-usable data, and is essential when a wind turbine controller relies on a lidar. To accomplish this, researchers from Avent Lidar Technology and the National Renewable Energy Laboratory first assessed and modeled the effect of extreme atmospheric events. This shows how a multirange lidar delivers measurements for a wide variety of conditions. Second, by using a theoretical approach and conducting an analysis of field feedback, we investigated the effects of the lidar setup on the wind turbine. This helps determine the optimal lidar mounting position at the back of the nacelle, and establishes a relationship between availability, turbine rpm, and lidar sampling time. Lastly, we considered the role of the wind field reconstruction strategies and the turbine controller on the definition and performance of a lidar's measurement availability.

17 WIND ENERGY↗
DOE OSTI2013

VOLTTRON - An Intelligent Agent Platform for the Smart Grid

The distributed nature of the Smart Grid, such as responsive loads, solar and wind generation, and automation in the distribution system present a complex environment not easily controlled in a centralized manner.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1979

MOD-1 Wind Turbine Generator Analysis and Design Report, Volume 2

The MOD-1 detail design is appended. The supporting analyses presented include a parametric system trade study, a verification of the computer codes used for rotor loads analysis, a metal blade study, and a definition of the design loads at each principal wind turbine generator interface for critical loading conditions. Shipping and assembly requirements, composite blade development, and electrical stability are also discussed.

Source record↗
NASA NTRS1973

Results of tests OA12 and IA9 in the Ames Research Center unitary plan wind tunnels on an 0.030-scale model of the space shuttle vehicle 2A to determine aerodynamic loads, volume 1

Tests were conducted in unitary plan wind tunnels on an 0.030-scale replica of the space shuttle vehicle configuration 2A. Aerodynamic loads data were obtained at Mach numbers from 0.6 to 3.5. The investigation included tests on the integrated (launch) configuration and tests on the isolated orbiter (entry configuration). The integrated vehicle was tested at angles of attack and sideslip from minus 8 deg to plus 8 deg. The isolated orbiter was tested at angles of attack from minus 15 deg to plus 40 deg and angles of sideslip from minus 10 deg to plus 10 deg are dictated by trajectory considerations. The effects of orbiter/external tank incidence and deflected control surfaces on aerodynamic loads were also investigated.

Spangler, R. H.↗
DOE OSTI2024

Validation of new and existing methods for time-domain simulations of turbulence and loads

We seek to obtain a second-by-second match between the simulated and measured structural loads of a utility-scale wind turbine. To obtain the one-to-one load simulations, we start with the furthest upstream component of the modeling chain: the turbulent inflow. We consider new and existing methods to generate constrained-turbulence flow fields. The new method is based on large-eddy simulations (LES) and machine learning (ML). The existing methods include Kaimal-based TurbSim and the superstatistical wind field model. The inflow measurements used to constrain these simulations are obtained with a nacelle-mounted scanning lidar. We compare the flow fields for the different inflow simulation approaches and validate their associated load predictions against measurements collected in the Rotor Aero-dynamics, Aeroelastics, and Wake (RAAW) field campaign. We find that the rotor-position control developed for this study is key in enabling the time match between measurements and simulations. When this control approach is used, the load simulation performance tracks with the inflow simulation fidelity, with LES+ML yielding errors ≤ 4% for the damage-equivalent loads of flapwise bending moment, and tower fore-aft bending moments.

17 WIND ENERGY↗
NASA NTRS1977

Load distribution on a close-coupled wing canard at transonic speeds

This paper reports on a wind-tunnel test where load distributions were obtained at transonic speeds on both the canard and wing surfaces of a closely-coupled wing-canard configuration. The investigation included detailed component and configuration arrangement studies to provide insight into the various aerodynamic interference effects for the leading-edge vortex flow conditions encountered. Data indicate that increasing the Mach number from 0.70 to 0.95 caused the wing leading-edge vortex to burst over the wing when the wing was in the presence of the high canard. For some of the outboard span locations, the leading-edge vortex reattachment streamline intersects the wing trailing edge inboard of these span locations, thus, the Kutta condition was not satisfied. In general, the effect of adding a canard was to reduce the lift inboard and somewhat increase the lift outboard similar to the trends that would have been expected had the flow been attached.

Gloss, B. B.↗