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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Microwave power - An energy transmission alternative for the year 2000

Recent technological advances related to the feasibility of efficient RF-dc rectification make it likely that by the year 2000 the transmission of power through space will have become a practical reality. Proposals have been made to power helicopters, aircraft, balloons, and rockets remotely. Other proposals consider the transfer of power from point to point on earth via relay through space or a transmission of power from large power sources in space. Attention has also been given to possibilities regarding the transmission of power between various points in the solar system. An outline is provided of the microwave power transmission system envisaged for the solar power satellite, taking into account the transmitting antenna, the receiver on earth, aspects of beam formation and control, transmitter options, the receiving antenna design, and cost and efficiency considerations.

Nalos, E.↗
NASA NTRS1982

CF6 jet engine diagnostics program. High pressure turbine roundness/clearance investigation

The effects of high pressure turbine clearance changes on engine and module performance was evaluated in addition to the measurement of CF6-50C high pressure turbine Stage 1 tip clearance and stator out-of-roundness during steady-state and transient operation. The results indicated a good correlation of the analytical model of round engine clearance response with measured data. The stator out-of-roundness measurements verified that the analytical technique for predicting the distortion effects of mechanical loads is accurate, whereas the technique for calculating the effects of certain circumferential thermal gradients requires some modifications. A potential for improvement in roundness was established in the order of 0.38 mm (0.015 in.), equivalent to 0.86 percent turbine efficiency which translates to a cruise SFC improvement of 0.36 percent. The HP turbine Stage 1 tip clearance performance derivative was established as 0.44 mm (17 mils) per percent of turbine efficiency at take-off power, somewhat smaller, therefore, more sensitive than predicted from previous investigations.

Howard, W. D.↗
NASA NTRS1982

Experiments on high bypass internal mixer nozzle jet noise

Model scale jet noise data are presented for a variety of internal lobed mixer nozzle configurations for take off power settings in a static environment. The results are presented for a 17.5 cm diameter fan nozzle to show the effect on noise levels caused by changes in geometric shape of the internal, or core flow, nozzle. The geometric variables include the lobe discharge angle, the number of lobes, spacing between the center plug and lobe valley, lobe side wall shape and axial contour of the lobes. An annular plug core flow nozzle was also tested and is used as a baseline for comparative purposes. Comparison of data from the internal lobed configurations showed that for comparative effect, in terms of the effect on full scale perceived noise levels, was caused by a change in the lobe discharge angle. The results showed that increasing the discharge angle caused an increase as large as 7 dB in sound pressure levels in the high frequency portion of the spectra. Changes in the other geometric variables cause negligible effects.

Goodykoontz, J. H.↗
NASA NTRS1990

Estimation Of Interference In Satellite/Ground Communications

Relative strengths of desired and interfering signals computed for known orbits. Satellite Interference Analysis and Simulation Using Personal Computers (AKSATINT) computer program calculates interference experienced by generic satellite communications receiving station from interfering satellite. Also computes interference-to-signal-power ratio, taking into account losses suffered by links. Of general use to designers of systems and managers of frequencies in selecting proper frequencies under interference scenarios. Written in BASIC.

Kantak, Anil V.↗
NASA NTRS1948

Natural icing of an axial-flow turbojet engine in flight for a single icing condition

An investigation has been conducted in natural icing conditions to determine the effect of ice formations on the performance of an axial-flow turbojet engine. One flight was made in an icing condition in which the liquid-water content varied from 0.077 to 0.490 gram per cubic meter and the average droplet size varied from 5.4 to 12.1 microns. During a period of 60 minutes in icing, at an engine speed of 11,000 rpm, the tail-pipe temperature increased from 865 degrees to 965 degrees F. and the jet thrust decreased from 1950 to 1700 pounds. Near the end of the icing period, the engine was satisfactorily accelerated to take-off power.

Acker, Loren W↗
NASA NTRS1943

Wind-Tunnel Tests of the 1/9-Scale Model of the Curtiss XP-62 Airplane with Various Vertical Tail Arrangements

The effect of various vertical tail arrangements upon the stability and control characteristics of an XP-62 fighter model was investigated. Rudder-free yaw characteristics with take-off power and flaps deflected were satisfactory after dorsal fin modifications. Directional stability was obtained with all modified vertical tails. Satisfactory rudder effectiveness resulted partly because the dual-rotation propellers produced no asymmetric yawing moments. Pedal forces in sideslips were undesirably large but may be easily reduced.

Wallace, Arthur R.↗
NASA NTRS2000

Separate Flow Nozzle Test Status Meeting

NASA Glenn, in partnership with US industry, completed an exhaustive experimental study on jet noise reduction from separate flow nozzle exhaust systems. The study developed a data base on various bypass ratio nozzles, screened quietest configurations and acquired pertinent data for predicting the plume behavior and ultimately its corresponding jet noise. Several exhaust system configurations provided over 2.5 EPNdB jet noise reduction at take-off power. These data were disseminated to US aerospace industry in a conference hosted by NASA GRC whose proceedings are shown in this report.

Saiyed, Naseem H.↗
NASA NTRS1946

Effect of an Auxiliary Belly Fuel Tank on the Low-Speed Static Stability Characteristics of a 1/5-Scale Model of the Grumman XF8F-1 Airplane, TED No. NACA 2384

In.order to determine the aerodynamic effects of an auxiliary belly fuel tank on the Grumman F8F-1 airplane, a wind-tunnel investigation was made on a l/5 - scale model of the Grumman XF8F-1 airplane. Pitch and yaw tests were made with the model in the cruising and landing configurations for windmilling and take-off power conditions. Tuft studies and static-pressure measurements were also made to determine the flow characteristics in the region of the fuel tank. It was found that, at low speed, the auxiliary fuel tank test conditions, especially with power on in the landing configuration at high lift coefficients. The static directional stability was decreased for most test conditions, but the addition of a fairing between the fuselage and fuel tank improved the directional stability slightly in the power-on clean condition. The effective dihedral and lateral force were increased for most of the conditions tested. The tuft studies and pressure measurements indicated that the removal of the away braces would improve the.flow characteristics considerably in the region of the fuel tank end might also decrease the buffeting of the belly tank at high speeds.

Cook, Charles B.↗
NASA NTRS2011

Sensor web

A Sensor Web formed of a number of different sensor pods. Each of the sensor pods include a clock which is synchronized with a master clock so that all of the sensor pods in the Web have a synchronized clock. The synchronization is carried out by first using a coarse synchronization which takes less power, and subsequently carrying out a fine synchronization to make a fine sync of all the pods on the Web. After the synchronization, the pods ping their neighbors to determine which pods are listening and responded, and then only listen during time slots corresponding to those pods which respond.

Delin, Kevin A.↗
NASA NTRS1986

Managing Ada development

The Ada programming language was developed under the sponsorship of the Department of Defense to address the soaring costs associated with software development and maintenance. Ada is powerful, and yet to take full advantage of its power, it is sufficiently complex and different from current programming approaches that there is considerable risk associated with committing a program to be done in Ada. There are also few programs of any substantial size that have been implemented using Ada that may be studied to determine those management methods that resulted in a successful Ada project. The items presented are the author's opinions which have been formed as a result of going through an experience software development. The difficulties faced, risks assumed, management methods applied, and lessons learned, and most importantly, the techniques that were successful are all valuable sources of management information for those managers ready to assume major Ada developments projects.

Green, James R.↗
NASA NTRS1947

Stick-Fixed Stability and Control Characteristics of the Consolidated Vultee Model 240 Airplane as Estimated from Tests of a 0.092-Scale Powered Model

Estimates of the static stick-fixed stability and control characteristics of the Consolidated Vultee model 240 airplane are presented in this report. The estimates are based on tests of a 0.092-scale powered model in the 10-foot wind tunnel of the Guggenheim Aeronautical Laboratory of the California Institute of Technology. Results of the analysis are evaluated in terms of the Army specifications for stability and control characteristics which are more specific and, in general, equal to or more rigid than the Civil Aeronautics Administration requirements. The stick-fixed stability and control characteristics of the Consolidated Vultee model 240 were found to be satisfactory except for the following: 1) Marginal longitudinal stability in the landing approach (flaps 30 deg, 50% minimum continuous power) with aft center of gravity (31% M.A.C.); 2) Marginal rudder control to hold zero sideslip in a climb after take-off with asymmetric power (flaps 30 deg, left engine inoperative, right engine delivering take-off power) with maximum rudder throw limited to +/- 18 deg; 3) Marginal dihedral effect with flaps 40 deg and engines delivering maximum continuous power.

McCullough, George B.↗
NASA NTRS2008

It's a Go

The Electrical Power Distribution Control Team takes on the task of determining power failures throughout the Orbiter. The Displays and Controls Team takes on the task of determining distribution, circuit breakers, and switch failures that might occur on the Orbiter or displays that stop working. This paper will identify the circuit packages I have put together for the D&C group, the redesigning of a Hybrid Driver Controller box, and the web designing the Displays and Controls website for easier access to information which can range from indicators to switches.

Welker, Joshua T.↗
NASA NTRS1990

The 'problem' with automation - Inappropriate feedback and interaction, not 'over-automation'

Automation in high-risk industry is often blamed for causing harm and increasing the chance of human error when failures occur. It is proposed that the problem is not the presence of automation, but rather its inappropriate design. The problem is that the operations are performed appropriately under normal conditions, but there is inadequate feedback and interaction with the humans who must control the overall conduct of the task. The problem is that the automation is at an intermediate level of intelligence, powerful enough to take over control which used to be done by people, but not powerful enough to handle all abnormalities. Moreover, its level of intelligence is insufficient to provide the continual, appropriate feedback that occurs naturally among human operators. To solve this problem, the automation should either be made less intelligent or more so, but the current level is quite inappropriate. The overall message is that it is possible to reduce error through appropriate design considerations.

Norman, D. A.↗
NASA NTRS2014

Using a Commercial Ethernet PHY Device in a Radiation Environment

This work involved placing a commercial Ethernet PHY on its own power boundary, with limited current supply, and providing detection methods to determine when the device is not operating and when it needs either a reset or power-cycle. The device must be radiation-tested and free of destructive latchup errors. The commercial Ethernet PHY's own power boundary must be supplied by a current-limited power regulator that must have an enable (for power cycling), and its maximum power output must not exceed the PHY's input requirements, thus preventing damage to the device. A regulator with configurable output limits and short-circuit protection (such as the RHFL4913, rad hard positive voltage regulator family) is ideal. This will prevent a catastrophic failure due to radiation (such as a short between the commercial device's power and ground) from taking down the board's main power. Logic provided on the board will detect errors in the PHY. An FPGA (field-programmable gate array) with embedded Ethernet MAC (Media Access Control) will work well. The error detection includes monitoring the PHY's interrupt line, and the status of the Ethernet's switched power. When the PHY is determined to be non-functional, the logic device resets the PHY, which will often clear radiation induced errors. If this doesn't work, the logic device power-cycles the FPGA by toggling the regulator's enable input. This should clear almost all radiation induced errors provided the device is not latched up.

Parks, Jeremy↗
NASA NTRS2016

Experimental Evaluation of Inlet Distortion on an Ejector Powered Hybrid Wing Body at Take-off and Landing Conditions

As part of the NASA Environmentally Responsible Aircraft project, an ultra high bypass ratio engine integration on a hybrid wing body demonstration was planned. The goal was to include engine and airframe integration concepts that reduced fuel consumption by at least 50% while still reducing noise 42 db cumulative on the ground. Since the engines would be mounted on the upper surface of the aft body of the aircraft, the inlets may be susceptible to vortex ingestion from the wing leading edge at high angles of attack and sideslip, and separated wing/body flow. Consequently, experimental and computational studies were conducted to collect flow surveys useful for characterizing engine operability. The wind tunnel tests were conducted at two NASA facilities, the 14- by 22-foot at NASA Langley and the 40- by 80-foot at NASA Ames Research Center. The test results included in this paper show that the distortion and pressure recovery levels were acceptable for engine operability. The CFD studies conducted to compare to experimental data showed excellent agreement for the angle of attacks examined, although failed to match the low speed experimental data at high sideslip angles.

Carter, Melissa B.↗
DOE OSTI2020

Integrated Transmission-and-Distribution System Modeling of Power Systems: State-of-the-Art and Future Research Directions

Integrated transmission-and-distribution (T&D) modeling is a new and developing method for simulating power systems. Interest in integrated T&D modeling is driven by the changes taking place in power systems worldwide that are resulting in more decentralized power systems with increasingly high levels of distributed energy resources. Additionally, the increasing role of the hitherto passive energy consumer in the management and operation of power systems requires more capable and detailed integrated T&D modeling to understand the interactions between T&D systems. Although integrated T&D modeling has not yet found widespread commercial application, its potential for changing the decades-old power system modeling approaches has led to several research efforts in the last few years that tried to (i) develop algorithms and software for steady-state and dynamic modeling of power systems and (ii) demonstrate the advantages of this modeling approach compared with traditional, separated T&D system modeling. In this paper, we provide a review of integrated T&D modeling research efforts and the methods employed for steady-state and dynamic modeling of power systems. We also discuss our current research in integrated T&D modeling and the potential directions for future research. This paper should be useful for power systems researchers and industry members because it will provide them with a critical summary of current research efforts and the potential topics where research efforts are needed to further advance and demonstrate the utility of integrated T&D modeling.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1982

Modeling and analysis of several classes of self-oscillating inverters. I - State-plane representations. II - Model extension, classification, and duality relationships

The present investigation is concerned with an important class of power conditioning networks, taking into account self-oscillating dc-to-square-wave transistor inverters. The considered circuits are widely used both as the principal power converting and processing means in many systems and as low-power analog-to-discrete-time converters for controlling the switching of the output-stage semiconductors in a variety of power conditioning systems. Aspects of piecewise-linear modeling are discussed, taking into consideration component models, and an equivalent-circuit model. Questions of singular point analysis and state plane representation are also investigated, giving attention to limit cycles, starting circuits, the region of attraction, a hard oscillator, and a soft oscillator.

Lee, F. C. Y.↗
DOE OSTI2024

Understanding Line Losses and Transformer Losses in Rural Isolated Distribution Systems

Rural, isolated power systems in the mainland U.S. and in states like Alaska and Hawaii are powered by assets like diesel generators. These rural, isolated power systems also cannot operate at the higher band of medium voltage (like 69kV). They are primarily in the 12 to 14 kV range to keep the cost of the distribution investments lower. Because of this mid-band medium voltage range, the line losses and distribution transformers losses consume significant diesel consumption (almost 10 percent of the peak load). This work considers one such power system powering an isolated system and presents key findings online losses, and transformer losses. Understanding and documenting the impacts is critical for these communities operating their power systems and take actions to reduce expensive diesel consumption. In this paper, we will present one such typical grid and model it in electromagnetic transients (EMT) domain. We used the tower structure, under ground cabling installation to develop high fidelity models of lines. We also used high fidelity models of distribution transformers to present the no-load losses and full load loses. We will also present technical solutions available commercially off-the-shelf to reduce these losses and reduce diesel consumption. This work will be a primer for communities to understand the technical challenges and to understand the possible solution available to solve such challenges for rural, isolated power system operators.

blackstart↗