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At least 379 records · Page 21

A comparison of Nuclear Thermal Propulsion concepts - Results of a workshop

A Nuclear Thermal Propulsion Workshop, co-sponsored by NASA, DOE and DOD, was held in Cleveland, Ohio on July 10-12, 1990. The workshop was to provide a database of nuclear propulsion concepts and technologies to assist in planning a nuclear propulsion project, identify high priority activities to be initiated early, and to provide cost and schedule estimates for development of concepts to technology readiness level 6 - full system verification in a simulated environment. Sixteen concepts were presented to Technology Review Panels (TRP), and discussed. Each concept was compared to a baseline manned Mars mission. A preliminary comparison of ratings made by the TRP's is presented herein for mission benefit, safety, technical risk, and development cost.

Clark, John S.↗

Overview of the NASA Lewis component technology program for Stirling power converters

This paper presents an update on the NASA Lewis Stirling component technology program. The component technology program has been organized as part of the NASA Lewis effort to develop Stirling converter technology for space power applications. The Stirling space power program is part of the High Capacity Power element of the NASA Civil Space Technology Initiative. Lewis is also providing technical management of a DOE-funded project to develop Stirling converter systems for distributed dish solar terrestrial power applications. The Lewis component technology program is coordinated with the primary contract efforts of these projects but is aimed at longer term issues, advanced technologies, and independent assessments. Topics to be discussed include bearings, linear alternators, controls and load interaction, materials/life assessment, and heat exchangers.

Thieme, Lanny G.↗

A comparison of nuclear thermal rocket development cost and schedule for piloted missions to Mars

In Fiscal Year 1992, NASA led a team, including DOE, universities, and industry, that evaluated various schedule and cost scenarios for development of nuclear thermal rocket propulsion systems for piloted Mars exploration. This paper summarizes the results of two of these studies: (1) a so-called 'Fast Track' approach, that would result in technology readiness level 6 (TRL-6-system ground testing complete) by the year 2000, and (2) a slower program that results in TRL-6 by 2006. Both scenarios included a concurrent engineering approach. Costs and schedules for the two scenarios are compared. In addition to the six-year schedule delay, the TRL-6 in 2006 scenario is estimated to increase the cost of the program from $4.7 billion to $5.8 billion (in real-year dollars). On the positive side, the technical program should be better, since nuclear testing of fuel elements may be possible prior to concept down-select, resulting in a more informed decision.

Clark, John S.↗

Progress report on nuclear propulsion for space exploration and science

NASA is continuing its work in cooperation with the Department of Energy (DOE) on nuclear propulsion - both nuclear thermal propulsion (NTP) and nuclear electric propulsion (NEP). The focus of the NTP studies remains on piloted and cargo missions to Mars (with precursor missions to the moon) although studies are under way to examine the potential uses of NTP for science missions. The focus of the NEP studies has shifted to space science missions with consideration of combining a science mission with an earlier demonstration of NEP using the SP-100 space nuclear reactor power system. Both NTP and NEP efforts are continuing in 1993 to provide a good foundation for science and exploration planners. Both NTP and NEP provide a very important transportation resource and in a number of cases enable missions that could not otherwise be accomplished.

Bennett, Gary L.↗

Space Exploration Initiative Fuels, Materials and Related Nuclear Propulsion Technologies Panel

This report was prepared by members of the Fuels, Materials and Related Technologies Panel, with assistance from a number of industry observers as well as laboratory colleagues of the panel members. It represents a consensus view of the panel members. This report was not subjected to a thorough review by DOE, NASA or DoD, and the opinions expressed should not be construed to represent the official position of these organizations, individually or jointly. Topics addressed include: requirement for fuels and materials development for nuclear thermal propulsion (NTP) and nuclear electric propulsion (NEP); overview of proposed concepts; fuels technology development plan; materials technology development plan; other reactor technology development; and fuels and materials requirements for advanced propulsion concepts.

Bhattacharyya, S. K.↗

Diffractive optics in adverse environments

An investigation at the Army Research Laboratory is in progress to characterize DOE performance in mil-spec environments. One of the most significant environmental influences is temperature. An analysis of a diffractive lens is presented in which optical performance is described as a function of temperature. In particular, we review the thermal dependence of focal length and diffraction efficiency. It is shown that the change in these parameters is independent of lens shape and relates only to material properties. Thermalized hybrid refractive/diffractive designs are discussed.

Behrmann, Gregory P.↗

Advanced nuclear thermal propulsion concepts

In 1989, a Presidential directive created the Space Exploration Initiative (SEI) which had a goal of placing mankind on Mars in the early 21st century. The SEI was effectively terminated in 1992 with the election of a new administration. Although the initiative did not exist long enough to allow substantial technology development, it did provide a venue, for the first time in 20 years, to comprehensively evaluate advanced propulsion concepts which could enable fast, manned transits to Mars. As part of the SEI based investigations, scientists from NASA, DoE National Laboratories, universities, and industry met regularly and proceeded to examine a variety of innovative ideas. Most of the effort was directed toward developing a solid-core, nuclear thermal rocket and examining a high-power nuclear electric propulsion system. In addition, however, an Innovative Concepts committee was formed and charged with evaluating concepts that offered a much higher performance but were less technologically mature. The committee considered several concepts and eventually recommended that further work be performed in the areas of gas core fission rockets, inertial confinement fusion systems, antimatter based rockets, and gas core fission electric systems. Following the committee's recommendations, some computational modeling work has been performed at Los Alamos in certain of these areas and critical issues have been identified.

Howe, Steven D.↗

The national geomagnetic initiative

The Earth's magnetic field, through its variability over a spectrum of spatial and temporal scales, contains fundamental information on the solid Earth and geospace environment (the latter comprising the atmosphere, ionosphere, and magnetosphere). Integrated studies of the geomagnetic field have the potential to address a wide range of important processes in the deep mantle and core, asthenosphere, lithosphere, oceans, and the solar-terrestrial environment. These studies have direct applications to important societal problems, including resource assessment and exploration, natural hazard mitigation, safe navigation, and the maintenance and survivability of communications and power systems on the ground and in space. Studies of the Earth's magnetic field are supported by a variety of federal and state agencies as well as by private industry. Both basic and applied research is presently supported by several federal agencies, including the National Science Foundation (NSF), U.S. Geological Survey (USGS), U.S. Department of Energy (DOE), National Oceanic and Atmospheric Administration (NOAA), National Aeronautics and Space Administration (NASA), and U.S. Department of Defense (DOD) (through the Navy, Air Force, and Defense Mapping Agency). Although each agency has a unique, well-defined mission in geomagnetic studies, many areas of interest overlap. For example, NASA, the Navy, and USGS collaborate closely in the development of main field reference models. NASA, NSF, and the Air Force collaborate in space physics. These interagency linkages need to be strengthened. Over the past decade, new opportunities for fundamental advances in geomagnetic research have emerged as a result of three factors: well-posed, first-order scientific questions; increased interrelation of research activities dealing with geomagnetic phenomena; and recent developments in technology. These new opportunities can be exploited through a national geomagnetic initiative to define objectives and encourage coordination of efforts among federal and state agencies, academic institutions, and industry to systematically characterize the spatial and temporal behavior of the Earth's magnetic field on local, regional, and global scales in order to understand the physical processes in the solid earth and geospace environment, and to apply this understanding to a variety of scientific problems and to technical and societal needs.

Source record↗

Atmospheric Radiation Measurement (ARM)/CART site

The DOE's Atmospheric Radiation Measurement (ARM) goals are as follows: (1) to provide an experimental test bed for improving the treatment of radiative transfer in global climate models (GCM's) under all kinds of cloud cover; and (2) to improve the parameterization and modeling of cloud formation, maintenance, dissipation, and related processes in GCM's. The scientific requirements which are most critical to the objectives of ARM are discussed.

Pennell, Bill↗

Development of high temperature liquid lubricants for low-heat rejection: Heavy duty diesel engines

The objective of this DOE program was to develop a liquid lubricant that will allow advanced diesel engines to operate at top ring reversal temperatures approaching 500 C and sump temperatures approaching 250 C. The lubricants developed demonstrated at marginal increase in sump temperature capability, approximately 15 C, and an increase in top ring reversal temperature. A 15W-40 synthetic lubricant designated HTL-4 was the best lubricant developed in terms of stability, wear control, deposit control dispersancy, and particulate emissions.

Wiczynski, P. D.↗

User interface development and metadata considerations for the Atmospheric Radiation Measurement (ARM) archive

This paper will discuss user interface development and the structure and use of metadata for the Atmospheric Radiation Measurement (ARM) Archive. The ARM Archive, located at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee, is the data repository for the U.S. Department of Energy's (DOE's) ARM Project. After a short description of the ARM Project and the ARM Archive's role, we will consider the philosophy and goals, constraints, and prototype implementation of the user interface for the archive. We will also describe the metadata that are stored at the archive and support the user interface.

Singley, P. T.↗

SP-100, a project manager's view

Born to meet the special needs of America's space effort, the SP-100 Program testifies to the cooperation among government agencies. The Department of Energy (DOE), the National Aeronautics and Space Administration (NASA), and the Defense Advanced Research Projects Agency (DARPA) are working together to produce a 100-kW power system for use in outer space. At this point in the effort, it is appropriate to review: The approach to meet program goals; the status of activities of the Project Office, managed by the Jet Propulsion Laboratory (JPL); and, because this is a meeting on materials, answers beings developed by the Project Office to vital questions on refractory alloy technology.

Truscello, Vincent C.↗

Advanced Turbine Technology Applications Project (ATTAP) 1993 annual report

This report summarizes work performed by AlliedSignal Engines, a unit of AlliedSignal Aerospace Company, during calendar year 1993, toward development and demonstration of structural ceramic technology for automotive gas turbine engines. This work was performed for the U.S. Department of Energy (DOE) under National Aeronautics and Space Administration (NASA) Contract DEN3-335, Advanced Turbine Technology Applications Project (ATFAP). During 1993, the test bed used to demonstrate ceramic technology was changed from the AlliedSignal Engines/Garrett Model AGT101 regenerated gas turbine engine to the Model 331-200(CT) engine. The 331-200(CT) ceramic demonstrator is a fully-developed test platform based on the existing production AlliedSignal 331-200(ER) gas turbine auxiliary power unit (APU), and is well suited to evaluating ceramic turbine blades and nozzles. In addition, commonality of the 331-200(CT) engine with existing gas turbine APU's in commercial service provides the potential for field testing of ceramic components. The 1993 ATTAP activities emphasized design modifications of the 331-200 engine test bed to accommodate ceramic first-stage turbine nozzles and blades, fabrication of the ceramic components, ceramic component proof and rig tests, operational tests of the test bed equipped with the ceramic components, and refinement of critical ceramic design technologies.

Source record↗

Thermal Barrier Coating Workshop

This document contains the agenda and presentation abstracts for the Thermal Barrier Coating Workshop, sponsored by NASA, DOE, and NIST. The workshop covered thermal barrier coating (TBC) issues related to applications, processing, properties, and modeling. The intent of the workshop was to highlight the state of knowledge on TBC's and to identify critical gaps in knowledge that may hinder TBC use in advanced applications. The workshop goals were achieved through presentations by 22 speakers representing industry, academia, and government as well as through extensive discussion periods.

Brindley, W. J.↗

Collected Papers on Wind Turbine Technology

R and D projects on electricity generating wind turbines were conducted at the NASA Lewis Research Center from 1973 to 1988. Most projects were sponsored by the U.S. Department of Energy (DOE), a major element of its Federal Wind Energy Program. Another large wind turbine project was by the Bureau of Reclamation of the U.S. Department of Interior (DOI). From 1988 to 1995, NASA wind energy activities have been directed toward the transfer of technology to commercial and academic organizations. As part of these technology transfer activities, previously unpublished manuscripts have been assembled and presented here to share the wind turbine research results with the wind energy community. A variety of wind turbine technology topics are discussed: Wind and wake models; Airfoil properties; Structural analysis and testing; Control systems; Variable speed generators; and acoustic noise. Experimental and theoretical results are discussed.

Spera, David A.↗

Control system design for the MOD-5A 7.3 mW wind turbine generator

This paper provides descriptions of the requirements analysis, hardware development and software development phases of the Control System design for the MOD-5A 7.3 mW Wind Turbine Generator. The system, designed by General Electric Company, Advanced Energy Programs Department, under contract DEN 3-153 with NASA Lewis Research Center and DOE, provides real time regulation of rotor speed by control of both generator torque and rotor torque. A variable speed generator system is used to provide both airgap torque control and reactive power control. The wind rotor is designed with segmented ailerons which are positioned to control blade torque. The central component of the control system, selected early in the design process, is a programmable controller used for sequencing, alarm monitoring, communication, and real time control. Development of requirements for use of aileron controlled blades and a variable speed generator required an analytical simulation that combined drivetrain, tower and blade elastic modes with wind disturbances and control behavior. An orderly two phase plan was used for controller software development. A microcomputer based turbine simulator was used to facilitate hardware and software integration and test.

Barton, Robert S.↗

Variable speed generator application on the MOD-5A 7.3 mW wind turbine generator

This paper describes the application of a Scherbiustat type variable speed subsystem in the MOD-5A Wind Turbine Generator. As designed by General Electric Company, Advanced Energy Programs Department, under contract DEN3-153 with NASA Lewis Research Center and DOE, the MOD-5A utilizes the subsystem for both starting assistance in a motoring mode and generation in a controlled airgap torque mode. Reactive power control is also provided. The Scherbiustat type arrangement of a wound rotor machine with a cycloconverter in the rotor circuit was selected after an evaluation of variable speed technologies that followed a system evaluation of drivetrain cost and risk. The paper describes the evaluation factors considered, the results of the evaluations and summarizes operating strategy and performance simulations.

Barton, Robert S.↗

Fuel cell systems for First Lunar Outpost-reactant storage option

The office of Space, DOE, appointed a Lunar Surface Power Working Group to review candidate systems for the First Lunar Outpost habitat. The working group met for a total of five days in the fall of 1992 and concluded that the candidate involving a photovoltaic unit, a fuel cell, a regenerator to recycle the reactants, and storage of oxygen and hydrogen gases was the most attractive for this application. Most of the volume (97 percent) and weight (63 percent) are taken up by the reactants and their storage tanks. Therefore, in my work for the Group, and in this report, I have concentrated on finding ways to reduce these volumes and weights. Three options were considered: (1) the baseline case considered in the preliminary system design, that of separate high pressure (200 bar) storage tanks; (2) the use of two of the descent storage propellant tanks wrapped with graphite fibers to increase the pressure capability; and (3) the use of cryogenic storage of reactants in the propellant tanks. The first option results in high storage tank mass and volume. The second option saves 90 percent of the volume by making use of the propellant tanks, but it has little if any weight advantages; the weight saved by not providing extra tanks for reactant storage is nearly entirely added back by the weight of the additional material (graphite fibers) to strengthen the propellant tanks. Use of the descent storage propellant tanks for storage of the fuel cell reactants as cryogenic liquids requires a gas liquefaction system. The weight of this system is expected to be less than that of the storage tanks but it would require development and testing to prove its reliability. The solar array would have to be 40 percent larger and the heat projection range would be 170 percent larger than for storage of reactants as high pressure gases. For a high power system (greater than 20 kW) the larger energy storage requirement would probably favor the cryogenic storage option.

Nelson, P. A.↗