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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 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
NASA NTRS2001

Fan Flutter Analysis Capability Enhanced

The trend in the design of advanced transonic fans for aircraft engines has been toward the use of complex high-aspect-ratio blade geometries with a larger number of blades and higher loading. In addition, integrally bladed disks or blisks are being considered in fan designs for their potential to reduce manufacturing costs, weight, and complexity by eliminating attachments. With such design trends, there is an increased possibility within the operating region of part-speed stall flutter (self-excited vibrations) that is exacerbated by the reduced structural damping of blisk fans. To verify the aeroelastic soundness of the design, the NASA Glenn Research Center is developing and validating an accurate aeroelastic prediction and analysis capability. Recently, this capability was enhanced significantly as described here.

Bakhle, Milind A.↗
NASA NTRS2005

Chemical Modeling for Studies of GeoTRACE Capabilities

Geostationary measurements of tropospheric pollutants with high spatial and temporal resolution will revolutionize the understanding and predictions of the chemically linked global pollutants aerosols and ozone. However, the capabilities of proposed geostationary instruments, particularly GeoTRACE, have not been thoroughly studied with model simulations. Such model simulations are important to answer the questions and allay the concerns that have been expressed in the atmospheric sciences community about the feasibility of such measurements. We proposed a suite of chemical transport model simulations using the EPA Models 3 chemical transport model, which obtains its meteorology from the MM-5 mesoscale model. The model output consists of gridded abundances of chemical pollutants and meteorological parameters every 30-60 minutes for cases that have occurred in the Eastern United States. This output was intended to be used to test the GeoTRACE capability to retrieve the tropospheric columns of these pollutants.

Source record↗
NASA NTRS2005

Transformational Spaceport and Range Capabilities Roadmap Interim Review to National Research Council External Review Panel

Contents include the following: Overview/Introduction. Roadmap Approach/Considerations. Roadmap Timeline/Spirals. Requirements Development. Spaceport/Range Capabilities. Mixed Range Architecture. User Requirements/Customer Considerations. Manifest Considerations. Emerging Launch User Requirements. Capability Breakdown Structure/Assessment. Roadmap Team Observations. Transformational Range Test Concept. Roadmap Team Conclusions. Next Steps.

Poniatowski, Karen↗
NASA NTRS2005

Space Communications Capability Roadmap Interim Review

Contents include the following: Identify the need for a robust communications and navigation architecture for the success of exploration and science missions. Describe an approach for specifying architecture alternatives and analyzing them. Establish a top level architecture based on a network of networks. Identify key enabling technologies. Synthesize capability, architecture and technology into an initial capability roadmap.

Spearing, Robert↗
NASA NTRS2005

Human Health and Support Systems Capability Roadmap Progress Review

The Human Health and Support Systems Capability Roadmap focuses on research and technology development and demonstration required to ensure the health, habitation, safety, and effectiveness of crews in and beyond low Earth orbit. It contains three distinct sub-capabilities: Human Health and Performance. Life Support and Habitats. Extra-Vehicular Activity.

Grounds, Dennis↗
NASA NTRS2005

Spacecraft Chemical Propulsion Systems at NASA's Marshall Space Flight Center: Heritage and Capabilities

NASA Marshall Space Flight Center (MSFC) is well known for its contributions to large ascent propulsion systems such as the Saturn V and the Space Shuttle. This paper highlights a lesser known but equally rich side of MSFC - its heritage in spacecraft chemical propulsion systems and its current capabilities for in-space propulsion system development and chemical propulsion research. The historical narrative describes the efforts associated with developing upper-stage main propulsion systems such as the Saturn S-IVB as well as orbital maneuvering and reaction control systems such as the S-IVB auxiliary propulsion system, the Skylab thruster attitude control system, and many more recent activities such as Chandra, the Demonstration of Automated Rendezvous Technology, X-37, the X-38 de-orbit propulsion system, the Interim Control Module, the US Propulsion Module, and several technology development activities. Also discussed are MSFC chemical propulsion research capabilities, along with near- and long-term technology challenges to which MSFC research and system development competencies are relevant.

McRight, Patrick S.↗
NASA NTRS2003

Short Takeoff and Vertical Landing Capability Upgraded in NASA Glenn's 9- by 15-Foot Low-Speed Wind Tunnel

The NASA Glenn Research Center supports short takeoff and vertical landing (STOVL) tests in its 9- by 15-Foot Low Speed Wind Tunnel (9 x 15 LSWT). As part of a facility capability upgrade, a dynamic actuation system (DAS) was fabricated to enhance the STOVL testing capabilities. The DAS serves as the mechanical interface between the 9 x 15 LSWT test section structure and the STOVL model to be tested. It provides vertical and horizontal translation of the model in the test section and maintains the model attitude (pitch, yaw, and roll) during translation. It also integrates a piping system to supply the model with exhaust and hot air to simulate the inlet suction and nozzle exhausts, respectively. Hot gas ingestion studies have been performed with the facility ground plane installed. The DAS provides vertical (ascent and descent) translation speeds of up to 48 in./s and horizontal translation speeds of up to 12 in./s. Model pitch variations of +/- 7, roll variations of +/- 5, and yaw variations of 0 to 180 deg can be accommodated and are maintained within 0.25 deg throughout the translation profile. The hot air supply, generated by the facility heaters and regulated by control valves, provides three separate temperature zones to the model for STOVL and hot gas ingestion testing. Channels along the supertube provide instrumentation paths from the model to the facility data system for data collection purposes. The DAS is supported by the 9 x 15 LSWT test section ceiling structure. A carriage that rides on two linear rails provides for horizontal translation of the system along the test section longitudinal axis. A vertical translation assembly, consisting of a cage and supertube, is secured to the carriage. The supertube traverses vertically through the cage on a set of linear rails. Both translation axes are hydraulically actuated and provide position and velocity profile control. The lower flange on the supertube serves as the model interface to the DAS. The supertube also serves as the exhaust path to the model and supports the hot air piping on its external surfaces. The DAS is currently being assembled at the 9 15 LSWT facility. Following assembly and installation, a series of checkouts will be performed to confirm the operation of the system.

Stark, David E.↗
NASA NTRS2004

New Dynamic Spin Rig Capabilities Used to Determine Rotating Blade Dynamics

The Dynamic Spin Rig Facility at the NASA Glenn Research Center is used to determine the structural response of rotating engine components without the effects of aerodynamic loading. Recently, this rig's capabilities were enhanced through the replacement of grease-lubricated ball bearings with magnetic bearings. Magnetic bearings offer a number of advantages--the most important here being that they not only fully support the rotor system, but excite it as well. Three magnetic bearings support the rotor and provide five axes of controlled motion: an x- and y-axis translation at each of two radial bearings and a z-axis translation in the vertical or axial direction. Sinusoidal excitation (most commonly used) can be imparted on the rotor through the radial magnetic bearings in either a fixed or rotating frame of reference. This excitation is added directly to the magnetic bearing control output. Since the rotor is fully levitated, large translations and rotations of the rotor system can be achieved. Some of the capabilities of this excitation system were determined and reported. The accelerations obtained at the tip of a titanium flat plate test article versus the swept sine excitation sent to both radial bearings in phase and perpendicular to the plane containing the two blades are shown. Recent tests required the excitation of fundamental bending and torsional blade resonances at rotor speeds up to 10,000 rpm. Successful fixed synchronous rotation of the excitation signal provided the best detectable blade resonant vibrations at excitation frequencies up to 1100 Hz for the particular blades of interest. A noncontacting laser measurement system was used to collect blade-tip motions. From these data, the amplitude and frequency of the motion could be determined as well as the blade damping properties. Damping could be determined using two methods: (1) free decay and (2) curve fitting the vibration amplitude as a function of frequency in and around the resonance of interest and using the half-power method. The free decay of a composite blade vibrating at its first bending resonance while rotating at 3000 rp is shown. This new system is currently being used to support the Efficient Low-Noise Fan project at Glenn. The damping properties of prototype hollow composite blades specially designed to reduce fan noise are currently being determined.

Provenza, Andrew J.↗
NASA NTRS2006

Summary of NASA Advanced Telescope and Observatory Capability Roadmap

The NASA Advanced Telescope and Observatory (ATO) Capability Roadmap addresses technologies necessary for NASA to enable future space telescopes and observatories operating in all electromagnetic bands, from x-rays to millimeter waves, and including gravity-waves. It lists capability priorities derived from current and developing Space Missions Directorate (SMD) strategic roadmaps. Technology topics include optics; wavefront sensing and control and interferometry; distributed and advanced spacecraft systems; cryogenic and thermal control systems; large precision structure for observatories; and the infrastructure essential to future space telescopes and observatories.

Stahl, H. Phil↗
NASA NTRS2006

Advances in Engine Test Capabilities at the NASA Glenn Research Center's Propulsion Systems Laboratory

The Propulsion Systems Laboratory at the National Aeronautics and Space Administration (NASA) Glenn Research Center is one of the premier U.S. facilities for research on advanced aeropropulsion systems. The facility can simulate a wide range of altitude and Mach number conditions while supplying the aeropropulsion system with all the support services necessary to operate at those conditions. Test data are recorded on a combination of steady-state and highspeed data-acquisition systems. Recently a number of upgrades were made to the facility to meet demanding new requirements for the latest aeropropulsion concepts and to improve operational efficiency. Improvements were made to data-acquisition systems, facility and engine-control systems, test-condition simulation systems, video capture and display capabilities, and personnel training procedures. This paper discusses the facility s capabilities, recent upgrades, and planned future improvements.

Pachlhofer, Peter M.↗
NASA NTRS1972

Force-Strain Characteristics and Rupture-Load Capability of Viking-Type Suspension-Line Material Under Dynamic Loading Conditions

A series of tests has been conducted to investigate the elastic behavior of Viking-type suspension-line material under dynamic loading conditions. Results indicate that there is a decrease in both rupture-load capability and elongation at rupture as the test strain rate is increased. Preliminary examination of force-strain characteristics indicates that, on the average, the material exhibits some type of viscous effect which results in a greater force being produced, for a particular value of strain, under dynamic loading conditions than that produced under quasi-static loading conditions. A great deal of uncertainty exists in defining a priori the tensile properties of viscoelastic materials, such as nylon or dacron, under dynamic loading conditions. Additional uncertainty enters the picture when woven configurations such as suspension,line material are considered. To eliminate these uncertainties, with respect to the Viking parachute configuration, a test program has been conducted to obtain data on the tensile properties of Viking-type suspension-line material over a wide range of strain rates. Based on preliminary examination of these data, the following conclusions can be drawn: 1. Material rupture-load capability decreases as strain-rate is increased. At strain rates above 75 percent/sec, no rupture loads were observed which would meet the minimum tensile strength specification of 880 pounds. 2. The material, on the average, exhibits some type of viscous effect which, for a particular value of strain, produces a greater load under dynamic loading conditions than that produced under quasi-static loading conditions.

Poole, Lamont R.↗
NASA NTRS2006

A highly capable arbitrary waveform generator for next generation radar systems

We are developing an Arbitrary Waveform Generator (AWG) to provide enhanced capability for radar applications. The current design will accommodate two waveform generators on a single unit for dual frequency operation. The basic architecture of this unit employs a Field Programmable Gate Array (FPGA) and a high speed and high precision Digital to Analog Converter (DAC) for direct digital synthesis. This AWG will be capable of up to 450 MHz bandwidth with ability for frequency notching. Phase fidelity of less than 1.2(sup o) deviation RMS is also achievable. This AWG operates with lower power consumption as compared with other waveform generators, which is advantageous for future spaceborne applications. This will enable radars to return higher precision data, to be reduced in complexity, and to operate in any band without interfering with dedicated bandwidths.

chirp generators↗
NASA NTRS2004

Future capabilities for the Deep Space Network

This paper will look at three new capabilities that are in different stages of development. First, turbo decoding, which provides improved telemetry performance for data rates up to about 1 Mbps, will be discussed. Next, pseudo-noise ranging will be presented. Pseudo-noise ranging has several advantages over the current sequential ranging, anmely easier operations, improved performance, and the capability to be used in a regenerative implementation on a spacecraft. Finally, Low Density Parity Check decoding will be discussed. LDPC codes can provide performance that matches or slightly exceed turbo codes, but are designed for use in the 10 Mbps range.

turbo code↗
NASA NTRS2005

Stennis Space Center Verification & Validation Capabilities

Scientists within NASA s Applied Sciences Directorate have developed a well-characterized remote sensing Verification & Validation (V&V) site at the John C. Stennis Space Center (SSC). This site enables the in-flight characterization of satellite and airborne high spatial and moderate resolution remote sensing systems and their products. The smaller scale of the newer high resolution remote sensing systems allows scientists to characterize geometric, spatial, and radiometric data properties using a single V&V site. The targets and techniques used to characterize data from these newer systems can differ significantly from the techniques used to characterize data from the earlier, coarser spatial resolution systems. Scientists are also using the SSC V&V site to characterize thermal infrared systems and active lidar systems. SSC employs geodetic targets, edge targets, radiometric tarps, atmospheric monitoring equipment, and thermal calibration ponds to characterize remote sensing data products. The SSC Instrument Validation Lab is a key component of the V&V capability and is used to calibrate field instrumentation and to provide National Institute of Standards and Technology traceability. This poster presents a description of the SSC characterization capabilities and examples of calibration data.

Pagnutti, Mary↗
NASA NTRS2007

The ROSSI X-Ray Timing Explorer: Capabilities, Achievements and Aims

The prime scientific objectives of the Rossi X-Ray Timing Explorer (RXTE) were the study of astrophysical compact objects: black holes (galactic and extragalactic), many types of neutron stars, and accreting white dwarfs. RXTE was successful in achieving its original observing objectives of large area and high time resolution observations with broadband (2-200 keV) spectra, scheduled flexibly enough to enable observations of targets of opportunity on any timescale greater than a few hours. These capabilities enabled qualitatively new discoveries about dynamical timescale phenomena related to neutron stars and black holes, phenomena which probe basic physics in the most extreme environments of gravity, density, and magnetic fields. RXTE has extended its lifetime by applying the proportional counter area selectively and maintains schedule flexibility by making use of the distribution of targets around the sky. Proposed future observations emphasize opportunity to discover and study additional millisecond pulsars, pursue the high frequency quasi-periodic oscillations in black hole transients, and connect high frequency phenomena with longer term characteristics. RXTE will continue to strongly support, for both galactic and extragalactic targets, combining RXTE observations with other wavelengths (from IR to TeV) or with other capabilities, such as high spectral resolution.

Swank, J. H.↗
NASA NTRS2006

High-Capacity Communications from Martian Distances Part 4: Assessment of Spacecraft Pointing Accuracy Capabilities Required For Large Ka-Band Reflector Antennas

Improved surface accuracy for deployable reflectors has brought with it the possibility of Ka-band reflector antennas with extents on the order of 1000 wavelengths. Such antennas are being considered for high-rate data delivery from planetary distances. To maintain losses at reasonable levels requires a sufficiently capable Attitude Determination and Control System (ADCS) onboard the spacecraft. This paper provides an assessment of currently available ADCS strategies and performance levels. In addition to other issues, specific factors considered include: (1) use of "beaconless" or open loop tracking versus use of a beacon on the Earth side of the link, and (2) selection of fine pointing strategy (body-fixed/spacecraft pointing, reflector pointing or various forms of electronic beam steering). Capabilities of recent spacecraft are discussed.

Hodges, Richard E.↗