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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 11: Advanced steam systems

A parametric analysis was made of three types of advanced steam power plants that use coal in order to have a comparison of the cost of electricity produced by them a wide range of primary performance variables. Increasing the temperature and pressure of the steam above current industry levels resulted in increased energy costs because the cost of capital increased more than the fuel cost decreased. While the three plant types produced comparable energy cost levels, the pressurized fluidized bed boiler plant produced the lowest energy cost by the small margin of 0.69 mills/MJ (2.5 mills/kWh). It is recommended that this plant be designed in greater detail to determine its cost and performance more accurately than was possible in a broad parametric study and to ascertain problem areas which will require development effort. Also considered are pollution control measures such as scrubbers and separates for particulate emissions from stack gases.

Wolfe, R. W.↗
NASA NTRS1978

Toxic substances alert program

A toxicity profile is provided, of 187 toxic substances procured by NASA Lewis Research Center during a 3 1/2 year period, including 27 known or suspected carcinogens. The goal of the program is to assure that the center's health and safety personnel are aware of the procurement and use of toxic substances and to alert and inform the users of these materials as to the toxic characteristics and the control measures needed to ensure their safe use. The program also provides a continuing record of the toxic substances procured, who procured them, what other toxic substances the user has obtained in the past, and where similar materials have been used elsewhere at the center.

Junod, T. L.↗
NASA NTRS1979

A unique facility for V/STOL aircraft hover testing

The Langley Impact Dynamics Research Facility (IDRF) was modified to obtain static force and moment data and to allow assessment of aircraft handling qualities during dynamic tethered hover flight. Test probe procedures were also established. Static lift and control measurements obtained are presented along with results of limited dynamic tethered hover flight.

Culpepper, R. G.↗
NASA NTRS1978

An innovative technique for static and dynamic V/STOL testing

Initial hover testing of the Navy's XFV-12A V/STOL technology prototype aircraft is being conducted in the former Lunar Lander Research Facility at the NASA Langley Research Center. The aircraft incorporates a unique lift/control concept for V/STOL flight. A key element in the development of this aircraft has been the application of existing hardware and facilities to conserve program funds. Adaptation of the NASA Gantry has created a V/STOL aircraft test facility with unique capability and flexibility. Static lift and control measurements can be obtained and dynamic hover flight can be conducted over a wide range of realistic test conditions.

Lewis, E. L.↗
NASA NTRS1980

Multichannel coincidence circuit

Digital circuit detects coincident pulses in two or more channels, and records time between primary pulses that are coincident with secondary pulses. Circuit has three major blocks: interval time subcircuit, measurement control subcircuit, and time sequence generator. Timer can be used in laser velocimeter or other instruments receiving data at irregular rates from two or more sources.

Clemmons, J. I., Jr.↗
NASA NTRS1984

Predicting Noise in Complex Aircraft Structures

Technique combines theoretical and empirical aspects of structural components. Experimental and analytical program produces test and analysis procedures for predicting extent of noise generated in aircraft. Purpose of program to develop ways of screening candidate materials considered for noise control and establish test procedures for verifying choice of particular control measure.

Unruh, J. F.↗
NASA NTRS1982

Recent results about fan noise: Its generation, radiation and suppression

Fan noise including its generation, radiation characteristics, and suppression by acoustic treatment is studied. In fan noise generation, results from engine and fan experiments, using inflow control measures to suppress noise sources related to inflow distortion and turbulence, are described. The suppression of sources related to inflow allows the experiments to focus on the fan or engine internal sources. Some of the experiments incorporated pressure sensors on the fan blades to sample the flow disturbances encountered by the blades. From these data some inferences can be drawn about the origins of the disturbances. Also, hot wire measurements of a fan rotor wake field are presented and related to the fan's noise signature. The radiation and the suppression of fan noise are dependent on the acoustic modes generated by the fan. Fan noise suppression and radiation is described by relating these phenomena to the mode cutoff ratio parameter. In addition to its utility in acoustic treatment design and performance prediction, cutoff ratio was useful in developing a simple description of the radiation pattern for broadband fan noise. Some of the findings using the cutoff ratio parameter are presented.

Feiler, C. E.↗
NASA NTRS1982

Design and test of aircraft engine isolators for reduced interior noise

Improved engine vibration isolation was proposed to be the most weight and cost efficient retrofit structure-borne noise control measure for single engine general aviation aircraft. A study was carried out the objectives: (1) to develop an engine isolator design specification for reduced interior noise transmission, (2) select/design candidate isolators to meet a 15 dB noise reduction design goal, and (3) carry out a proof of concept evaluation test. Analytical model of the engine, vibration isolators and engine mount structure were coupled to an empirical model of the fuselage for noise transmission evaluation. The model was used to develop engine isolator dynamic properties design specification for reduced noise transmission. Candidate isolators ere chosen from available product literature and retrofit to a test aircraft. A laboratory based test procedure was then developed to simulate engine induced noise transmission in the aircraft for a proof of concept evaluation test. Three candidate isolator configurations were evaluated for reduced structure-borne noise transmission relative to the original equipment isolators.

Unruh, J. F.↗
NASA NTRS1985

Recent materials problems relating to catastrophic balloon failures

Balloons fabricated of thin polyethylene materials have provided relatively inexpensive and reliable scientific research platforms for approximately three decades. Reliability of the modern day balloon, as launched by the U.S.A. National Scientific Balloon Facility (NSBF), has been approximately 85 percent. Recent balloon failures, coupled with an increased ocurrence of catastrophic failures, created grave concern over the integrity of the present balloon inventory of the U.S.A. National Aeronautics and Space Administration (NASA). An investigative team was established by NASA to review the circumstances surrounding the catastrophic balloon failures, determine the cause and to make recommendations to correct the problem and to prevent its reoccurrence. The most probable cause of failure as determined by the investigation was the polyethylene balloon film, although the film had passsed the established standard quality control measures of the film manufacturer. The approach, findings, and conclusions of the investigation are presented along with planned procedures to assure future quality balloon film for NASA balloons.

Smith, I. S.↗
NASA NTRS1986

The role of plant disease in the development of controlled ecological life support systems

Plant diseases could be important factors affecting growth of higher plants in Closed Ecological Life Support Systems (CELSS). Disease control, therefore, will be needed to maintain healthy plants. The most important controls should be aimed at preventing the introduction, reproduction and spread of pathogens and preventing plant infection. An integrared ease control program will maximize that approach. In the design and operation of CELSS, plant disease should be considered an important aspect of plant growth. The effects of plant diseases are reviewed and several disease control measures are discussed.

Nelson, B.↗
NASA NTRS1986

Effects of simulator variations on the fidelity of a UH-60 Black Hawk simulation

The validity of the vertical motion simulator used to simulate the UH-60A Black Hawk helicopter is evaluated. Aircraft simulation of bob-up, hover turn, and dash/quick stop manuevers are compared to actual flight data. The effects of variations in the simulator's visual and motion characteristics on the simulation data are investigated. Data obtained with the nonintrusive parameter identification procedure and optimal control measures are applied to the helicopter math model used for real-time aircraft simulation. Analysis of the model reveals that the simulated aircraft is underdamped, and the changes in the visual reference have the greatest effect on the ability of the pilot to perform the maneuvers.

Cleveland, W. B.↗
NASA NTRS1987

Test procedures for detection of in-flight propeller-induced structure-borne noise

A potentially important source of structure-borne interior noise transmission in advanced turboprop aircraft is the impingement of the propeller wake/vortex on downstream aerodynamic surfaces. It can only be safely assumed that this potential source of interior noise may well hold up achievable interior noise levels unless noise control measures are conscientiously incorporated into the aircraft design. Through the use of a laboratory based test apparatus, techniques were developed to estimate the level of in-flight structure-borne noise transmission from combined frequency response function ground testing and in-flight structural response measurements. All phases of the test procedure were simulated in the laboratory and the expected level of accuracy of the procedure is addressed.

Unruh, J. F.↗
NASA NTRS1987

Detection of in-flight propeller-induced structure-borne noise

A potentially important source of structure-borne interior noise transmission in advanced turboprop aircraft is the impingement of the propeller wake/vortex on downstream aerodynamic surfaces. It can be safely assumed that this potential source of interior noise may well adversely affect achievable interior noise levels unless noise control measures are conscientiously incorporated into the aircraft design. Through the use of a laboratory-based test apparatus, techniques were developed to estimate the level of in-flight structure-borne noise transmission from combined frequency response function ground testing and in-flight structural response measurements. All phases of the procedure were simulated in the laboratory and the expected level of accuracy of the procedure is addressed.

Unruh, J. F.↗
NASA NTRS1987

Development of contamination requirements for spaceborne optical instrumentation

High performance satellites and critical surfaces aboard advanced long-life spacecraft require effective contamination control measures to maintain performance stability and to ensure data accuracy. Contamination is said to exist and be of concern if a spacecraft or launch vehicle produced material interferes with the intended performance of a surface or sensor. This paper will discuss the development of contamination requirements for spaceborne optical instrumentation. In addition, a comparison of instrument contamination requirements to measured instrument degradation levels for mission activities will be presented. If maintained, these requirements ensure against undesirable instrument degradation due to the contamination environment created by fabrication, launch, mission activities, ambient atmosphere and the instruments themselves.

Hansen, Patricia A.↗
NASA NTRS1989

On performing exobiology experiments on an earth-orbital platform with the Gas-Grain Simulation Facility

Laboratory simulations of gas-dust interactions performed on Space Station Freedom in the Gas-Grain Simulation Facility (GGSF) are considered for studying the nature of bodies in the solar system. The GGSF includes a 4-10 liter chamber for experiments with the capability for environmental control, measurement, levitation, and energy. The simulations can provide low gas pressure and dust density in a microgravitational environment.

Huntington, Judith L.↗
NASA NTRS1992

Dynamic analysis to evaluate viscoelastic passive damping augmentation for the Space Shuttle Remote Manipulator System

The effectiveness of constrained viscoelastic layer damping treatment designs is evaluated separately as passive control measures for low frequency joint dominated modes and higher frequency boom flexure dominated modes using a NASTRAN finite element analysis. Passive damping augmentation is proposed which is based on a constrained viscoelastic layer damping treatment applied to the surface of the manipulators's flexible booms. It is pointed out that even the joint compliance dominated modes can be damped to some degree through appropriate design of the treatment.

Alberts, Thomas E.↗
NASA NTRS1994

Improved Micromachined Transducers

Sensor systems of proposed type incorporate micromachined silicon-based structures as electrostatic force and displacement actuators and micromachined quantum-mechanical-tunneling electrodes as one form of displacement transducers, along with electronic circuits providing multiple electrical stimuli to displacement electrodes for measurement, calibration, monitoring of sensor status, and adjustment. Concept applicable to accelerometers, seismometers, geophones, magnetometers, pressure gauges, and other sensors in which phenomena of interest measured in terms of forces on, and/or displacements of, structural components. Provides completely remote measurement, control, health monitoring, treatment, and like, using telemetry commands.

Hartley, Frank T.↗
NASA NTRS1992

An improved approach for flight readiness certification: Methodology for failure risk assessment and application examples, volume 1

An improved methodology for quantitatively evaluating failure risk of spaceflight systems to assess flight readiness and identify risk control measures is presented. This methodology, called Probabilistic Failure Assessment (PFA), combines operating experience from tests and flights with engineering analysis to estimate failure risk. The PFA methodology is of particular value when information on which to base an assessment of failure risk, including test experience and knowledge of parameters used in engineering analyses of failure phenomena, is expensive or difficult to acquire. The PFA methodology is a prescribed statistical structure in which engineering analysis models that characterize failure phenomena are used conjointly with uncertainties about analysis parameters and/or modeling accuracy to estimate failure probability distributions for specific failure modes. These distributions can then be modified, by means of statistical procedures of the PFA methodology, to reflect any test or flight experience. Conventional engineering analysis models currently employed for design of failure prediction are used in this methodology. The PFA methodology is described and examples of its application are presented. Conventional approaches to failure risk evaluation for spaceflight systems are discussed, and the rationale for the approach taken in the PFA methodology is presented. The statistical methods, engineering models, and computer software used in fatigue failure mode applications are thoroughly documented.

Moore, N. R.↗