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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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NASA NTRS1990

A novel sample-positioning system for microgravity application

This paper proposes a novel method for sample positioning in containerless processing at microgravity, using a system based on pulsed lasers. The method has two attributes. First, by generating beams that cancel out vectorially, the suspended material can be heated without being accelerated, a feature that can be used in melting and heat-treatment applications. Second, the specimen can be positioned within a fairly large work space. It is emphasized that this method can service a regime unfulfilled by the other levitation methods, such as electromagnetic levitation, active magnetic suspension, acoustic levitation, of electrostatic suspension.

Sridharan, G.↗

NASA NTRS1991

Propulsion simulator for magnetically-suspended wind tunnel models

The objective of phase two of a current investigation sponsored by NASA Langley Research Center is to demonstrate the measurement of aerodynamic forces/moments, including the effects of exhaust gases, in magnetic suspension and balance system (MSBS) wind tunnels. Two propulsion simulator models are being developed: a small-scale and a large-scale unit, both employing compressed, liquified carbon dioxide as propellant. The small-scale unit was designed, fabricated, and statically-tested at Physical Sciences Inc. (PSI). The large-scale simulator is currently in the preliminary design stage. The small-scale simulator design/development is presented, and the data from its static firing on a thrust stand are discussed. The analysis of this data provides important information for the design of the large-scale unit. A description of the preliminary design of the device is also presented.

Joshi, Prakash B.↗

NASA NTRS1987

Advanced experimental techniques for transonic wind tunnels - Final lecture

A philosophy of experimental techniques is presented, suggesting that in order to be successful, one should like what one does, have the right tools, stick to the job, avoid diversions, work hard, interact with people, be informed, keep it simple, be self sufficient, and strive for perfection. Sources of information, such as bibliographies, newsletters, technical reports, and technical contacts and meetings are recommended. It is pointed out that adaptive-wall test sections eliminate or reduce wall interference effects, and magnetic suspension and balance systems eliminate support-interference effects, while the problem of flow quality remains with all wind tunnels. It is predicted that in the future it will be possible to obtain wind tunnel results at the proper Reynolds number, and the effects of flow unsteadiness, wall interference, and support interference will be eliminated or greatly reduced.

Kilgore, Robert A.↗

NASA NTRS1991

Interference-free measurements of the subsonic aerodynamics of slanted-base ogive cylinders

Drag, lift, pitching moment, and base-pressure measurements have been made, free of support interference, on a range of slanted-base ogive cylinders, using the NASA Langley Research Center 13-in magnetic suspension and balance system. Test Mach numbers were in the range 0.04-0.2. Two types of wake flow were observed, a quasi-symmetric turbulent closure or a longitudinal vortex flow. Aerodynamic characteristics differ dramatically between the two wake types. Drag measurements are shown to be in agreement with previous tests. A hysteretic behavior of the wake with varying Reynold's number has been discovered for the 45-deg base. An interaction between forebody boundary-layer state and wake flow and base pressures has been detected for higher slant angles.

Britcher, Colin P.↗

NASA NTRS1991

NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 14: An analysis of the technical communications practices reported by Israeli and US aerospace engineers and scientists

As part of Phase 4 of the NASA/DoD Aerospace Knowledge Diffusion Research Project, two pilot studies were conducted that investigated the technical communications practices of Israeli and U.S. aerospace engineers and scientists. Both studies had the same five objectives: first, to solicit the opinions of aerospace engineers and scientists regarding the importance of technical communications to their profession; second, to determine the use and production of technical communications by aerospace engineers and scientists; third, to seek their view about the appropriate content of an undergraduate course in technical communications; fourth, to determine aerospace engineers' and scientists' use of libraries, technical information centers, and on-line databases; and fifth, to determine the use and importance of computer and information technology to them. A self-administered questionnaire was mailed to randomly selected U.S. aerospace engineers and scientists who are working in cryogenics, adaptive walls, and magnetic suspension. A slightly modified version was sent to Israeli aerospace engineers and scientists working at Israel Aircraft Industries, LTD. Responses of the Israeli and U.S. aerospace engineers and scientists to selected questions are presented in this paper.

Barclay, Rebecca O.↗

NASA NTRS1992

Vibration isolation technology development to demonstration

The main thrust of these studies has resulted in an active inertial feedforward/feedback isolation system. This prototype magnetic suspension system has been demonstrated in a laboratory setting in six degrees-of-freedom and has been preliminarily characterized in its isolation performance with favorable results. This isolation system consists of a closed loop digital control system referencing a platform around six relative and six inertial sensors. These sensors control the isolated mass through nine attractive electromagnetic actuators with a system capability of +/- three-tenths of an inch travel in three dimensions. The development of a prototype system from design to fabrication leads directly into the demonstration phase of the project which will attempt a low gravity environmental demonstration of engineering hardware for the isolation of a scientific payload. The demonstration phase of the project will use an aircraft low gravity maneuver to establish a research testbed for the study of isolation hardware and control strategies in an off-loaded environment. In developing this demonstration capability the Lewis Learjet aircraft has been characterized through its parabolic flight maneuvers and a trunnioned experimental volume has been designed for the test of both active and passive isolation packages. This vibration isolation testbed is operational and has two data acquisition systems available for both autonomous and interactive operation, with a combined input capability of 32 channels.

Grodsinsky, Carlos↗

NASA NTRS1993

Six-Degree-Of-Freedom Magnetic Vibration Isolator

Feedback control provides soft mount and damping of vibrations. Active magnetic suspension system centers inner structure in position and orientation with respect to principal Cartesian coordinate axes of base or outer structure, stationary with respect to building or vehicle. System helps to isolate suspended mass from vibrations of building or vehicle. Designed to isolate 500-kg experimental apparatus from vibrations of spacecraft, but also used on Earth, provided that its z axis vertical and system assisted by low-stiffness vertical spring that, in steady state, holds up inner structure at nominal vertical position.

Gerver, Michael J.↗

NASA NTRS1993

Actively Controlled Magnetic Vibration-Isolation System

Prototype magnetic suspension system with active control isolates object from vibrations in all six degrees of freedom at frequencies as low as 0.01 Hz. Designed specifically to protect instruments aboard spacecraft by suppressing vibrations to microgravity levels; basic control approach used for such terrestrial uses as suppression of shocks and other vibrations in trucks and railroad cars.

Grodsinky, Carlos M.↗

NASA NTRS1993

Spray-Deposited Superconductor/Polymer Coatings

Coatings that exhibit the Meissner effect formed at relatively low temperature. High-temperature-superconductor/polymer coatings that exhibit Meissner effect deposited onto components in variety of shapes and materials. Simple, readily available equipment needed in coating process, mean coatings produced economically. Coatings used to keep magnetic fields away from electronic circuits in such cryogenic applications as magnetic resonance imaging and detection of infrared, and in magnetic suspensions to provide levitation and/or damping of vibrations.

Wise, Stephanie A.↗

NASA NTRS1993

Development of superconducting YBa2Cu3O(x) wires with low resistance electrical contacts

Materials exhibiting superconductivity above liquid nitrogen temperatures (77 K) will enable new applications of this phenomena. One of the first commercial applications of this technology will be superconducting magnets for medical imaging. However, a large number of aerospace applications of the high temperature superconducting materials have also been identified. These include magnetic suspension and balance of models in wind tunnels and resistanceless leads to anemometers. The development of superconducting wires fabricated from the ceramic materials is critical for these applications. The progress in application of a patented fiber process developed by Clemson University for the fabrication of superconducting wires is reviewed. The effect of particle size and heat treatment on the quality of materials is discussed. Recent advances made at Christopher Newport College in the development of micro-ohm resistance electrical contacts which are capable of carrying the highest reported direct current to this material is presented.

Buoncristiani, A. M.↗

NASA NTRS1993

Robust tracking control of a magnetically suspended rigid body

This study is an application of H-infinity and microsynthesis for designing robust tracking controllers for the Large Angle Magnetic Suspension Test Facility. The modeling, design, analysis, simulation, and testing of a control law that guarantees tracking performance under external disturbances and model uncertainties is investigated. The type of uncertainties considered and the tracking performance metric used is discussed. This study demonstrates the tradeoff between tracking performance at low frequencies and robustness at high frequencies. Two sets of controllers were designed and tested. The first set emphasized performance over robustness, while the second set traded off performance for robustness. Comparisons of simulation and test results are also included. Current simulation and experimental results indicate that reasonably good robust tracking performance can be attained for this system, using multivariable robust control approach.

Lim, Kyong B.↗

NASA NTRS1992

Propulsion simulator for magnetically-suspended wind tunnel models

In order to demonstrate the measurement of aerodynamic forces/moments, including the effects of exhaust jets in Magnetic Suspension and Balance System (MSBS) wind tunnels, two propulsion simulator models were developed at Physical Sciences Inc. (PSI). Both the small-scale model (1 in. diameter X 8 in. long) and the large-scale model (2.5 in. diameter X 15 in. long) employed compressed, liquefied carbon dioxide as a propellant. The small-scale simulator, made from a highly magnetizable iron alloy, was demonstrated in the 7 in. MSBS wind tunnel at the University of Southampton. It developed a maximum thrust of approximate 1.3 lbf with a 0.098 in. diameter nozzle and 0.7 lbf with a 0.295 in. diameter nozzle. The Southampton MSBS was able to control the simulator at angles-of attack up to 20 deg. The large-scale simulator was demonstrated to operate in both a steady-state and a pulse mode via a miniaturized solinoid valve. It developed a stable and repeatable thrust of 2.75 lbf over a period of 4s and a nozzle pressure ratio (NPR) of 5.

Joshi, P. B.↗

NASA NTRS1993

Effects of window size and shape on accuracy of subpixel centroid estimation of target images

A new algorithm is presented for increasing the accuracy of subpixel centroid estimation of (nearly) point target images in cases where the signal-to-noise ratio is low and the signal amplitude and shape vary from frame to frame. In the algorithm, the centroid is calculated over a data window that is matched in width to the image distribution. Fourier analysis is used to explain the dependency of the centroid estimate on the size of the data window, and simulation and experimental results are presented which demonstrate the effects of window size for two different noise models. The effects of window shape were also investigated for uniform and Gaussian-shaped windows. The new algorithm was developed to improve the dynamic range of a close-range photogrammetric tracking system that provides feedback for control of a large gap magnetic suspension system (LGMSS).

Welch, Sharon S.↗

NASA NTRS1993

Research and test facilities

A description is given of each of the following Langley research and test facilities: 0.3-Meter Transonic Cryogenic Tunnel, 7-by 10-Foot High Speed Tunnel, 8-Foot Transonic Pressure Tunnel, 13-Inch Magnetic Suspension & Balance System, 14-by 22-Foot Subsonic Tunnel, 16-Foot Transonic Tunnel, 16-by 24-Inch Water Tunnel, 20-Foot Vertical Spin Tunnel, 30-by 60-Foot Wind Tunnel, Advanced Civil Transport Simulator (ACTS), Advanced Technology Research Laboratory, Aerospace Controls Research Laboratory (ACRL), Aerothermal Loads Complex, Aircraft Landing Dynamics Facility (ALDF), Avionics Integration Research Laboratory, Basic Aerodynamics Research Tunnel (BART), Compact Range Test Facility, Differential Maneuvering Simulator (DMS), Enhanced/Synthetic Vision & Spatial Displays Laboratory, Experimental Test Range (ETR) Flight Research Facility, General Aviation Simulator (GAS), High Intensity Radiated Fields Facility, Human Engineering Methods Laboratory, Hypersonic Facilities Complex, Impact Dynamics Research Facility, Jet Noise Laboratory & Anechoic Jet Facility, Light Alloy Laboratory, Low Frequency Antenna Test Facility, Low Turbulence Pressure Tunnel, Mechanics of Metals Laboratory, National Transonic Facility (NTF), NDE Research Laboratory, Polymers & Composites Laboratory, Pyrotechnic Test Facility, Quiet Flow Facility, Robotics Facilities, Scientific Visualization System, Scramjet Test Complex, Space Materials Research Laboratory, Space Simulation & Environmental Test Complex, Structural Dynamics Research Laboratory, Structural Dynamics Test Beds, Structures & Materials Research Laboratory, Supersonic Low Disturbance Pilot Tunnel, Thermal Acoustic Fatigue Apparatus (TAFA), Transonic Dynamics Tunnel (TDT), Transport Systems Research Vehicle, Unitary Plan Wind Tunnel, and the Visual Motion Simulator (VMS).

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NASA NTRS1994

Active magnetic bearing control loop modeling for a finite element rotordynamics code

A mathematical model of an active electromagnetic bearing which includes the actuator, the sensor and the control system is developed and implemented in a specialized finite element code for rotordynamic analysis. The element formulation and its incorporation in the model of the machine are described in detail. A solution procedure, based on a modal approach in which the number of retained modes is controlled by the user, is then shown together with other procedures for computing the steady-state response to both static and unbalance forces. An example of application shows the numerical results obtained on a model of an electric motor suspended on a five active-axis magnetic suspension. The comparison of some of these results with the experimental characteristics of the actual system shows the ability of the present model to predict its performance.

Genta, Giancarlo↗

NASA NTRS1994

Robust tracking control of a magnetically suspended rigid body

This study is an application of H-infinity and micro-synthesis for designing robust tracking controllers for the Large Angle Magnetic Suspension Test Facility. The modeling, design, analysis, simulation, and testing of a control law that guarantees tracking performance under external disturbances and model uncertainties is investigated. The type of uncertainties considered and the tracking performance metric used is discussed. This study demonstrates the tradeoff between tracking performance at low frequencies and robustness at high frequencies. Two sets of controllers were designed and tested. The first set emphasized performance over robustness, while the second set traded off performance for robustness. Comparisons of simulation and test results are also included. Current simulation and experimental results indicate that reasonably good robust tracking performance can be attained for this system using multivariable robust control approach.

Lim, Kyong B.↗

NASA NTRS1994

Concept verification of three dimensional free motion simulator for space robot

In the development of automatic assembling technologies for space structures, it is an indispensable matter to investigate and simulate the movements of robot satellites concerned with mission operation. The movement investigation and simulation on the ground will be effectively realized by a free motion simulator. Various types of ground systems for simulating free motion have been proposed and utilized. Some of these methods are a neutral buoyancy system, an air or magnetic suspension system, a passive suspension balance system, and a free flying aircraft or drop tower system. In addition, systems can be simulated by computers using an analytical model. Each free motion simulation method has limitations and well known problems, specifically, disturbance by water viscosity, limited number of degrees-of-freedom, complex dynamics induced by the attachment of the simulation system, short experiment time, and the lack of high speed super-computer simulation systems, respectively. The basic idea presented here is to realize 3-dimensional free motion. This is achieved by combining a spherical air bearing, a cylindrical air bearing, and a flat air bearing. A conventional air bearing system has difficulty realizing free vertical motion suspension. The idea of free vertical suspension is that a cylindrical air bearing and counter balance weight realize vertical free motion. This paper presents a design concept, configuration, and basic performance characteristics of an innovative free motion simulator. A prototype simulator verifies the feasibility of 3-dimensional free motion simulation.

Okamoto, Osamu↗

NASA NTRS1996

Structures Division 1994 Annual Report

The NASA Lewis Research Center Structures Division is an international leader and pioneer in developing new structural analysis, life prediction, and failure analysis related to rotating machinery and more specifically to hot section components in air-breathing aircraft engines and spacecraft propulsion systems. The research consists of both deterministic and probabilistic methodology. Studies include, but are not limited to, high-cycle and low-cycle fatigue as well as material creep. Studies of structural failure are at both the micro- and macrolevels. Nondestructive evaluation methods related to structural reliability are developed, applied, and evaluated. Materials from which structural components are made, studied, and tested are monolithics and metal-matrix, polymer-matrix, and ceramic-matrix composites. Aeroelastic models are developed and used to determine the cyclic loading and life of fan and turbine blades. Life models are developed and tested for bearings, seals, and other mechanical components, such as magnetic suspensions. Results of these studies are published in NASA technical papers and reference publication as well as in technical society journal articles. The results of the work of the Structures Division and the bibliography of its publications for calendar year 1994 are presented.

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