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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

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NASA NTRS1989

Efficient optimization of integrated aerodynamic-structural design

Techniques for reducing the computational complexity of multidisciplinary design optimization (DO) of aerodynamic structures are described and demonstrated. The basic principles of aerodynamic and structural DO are reviewed; the formulation of the combined DO problem is outlined; and particular attention is given to (1) the application of perturbation methods to cross-sensitivity computations and (2) numerical approximation procedures. Trial DOs of a simple sailplane design are presented in tables and graphs and discussed in detail. The IBM 3090 CPU time for the entire integrated DO was reduced from an estimated 10 h to about 6 min.

Haftka, R. T.↗

NASA NTRS1989

General approach and scope

This paper describes a joint activity involving NASA and Army researchers at the NASA Langley Research Center to develop optimization procedures aimed at improving the rotor blade design process by integrating appropriate disciplines and accounting for all of the important interactions among the disciplines. The disciplines involved include rotor aerodynamics, rotor dynamics, rotor structures, airframe dynamics, and acoustics. The work is focused on combining these five key disciplines in an optimization procedure capable of designing a rotor system to satisfy multidisciplinary design requirements. Fundamental to the plan is a three-phased approach. In phase 1, the disciplines of blade dynamics, blade aerodynamics, and blade structure will be closely coupled, while acoustics and airframe dynamics will be decoupled and be accounted for as effective constraints on the design for the first three disciplines. In phase 2, acoustics is to be integrated with the first three disciplines. Finally, in phase 3, airframe dynamics will be fully integrated with the other four disciplines. This paper deals with details of the phase 1 approach and includes details of the optimization formulation, design variables, constraints, and objective function, as well as details of discipline interactions, analysis methods, and methods for validating the procedure.

Adelman, Howard M.↗

NASA NTRS1989

Validation of the procedures

Validation strategies are described for procedures aimed at improving the rotor blade design process through a multidisciplinary optimization approach. Validation of the basic rotor environment prediction tools and the overall rotor design are discussed.

Mantay, Wayne R.↗

NASA NTRS1990

Structural tailoring of select fiber composite structures

A multidisciplinary design process for aerospace propulsion composite structures was formalized and embedded into computer codes. These computer codes are streamlined to obtain tailored designs for select composite structures. The codes available are briefly described with sample cases to illustrate their applications. The sample cases include aircraft engine blades, propfans (turboprops), flat, and cylindrical panels. Typical results illustrate that the use of these codes enable the designer to obtain designs which meet all the design requirements with maximum benefits in efficiency, noise, weight or thermal distortions.

Chamis, Christos C.↗

NASA NTRS1990

Small helium-cooled infrared telescope experiment for Spacelab-2 (IRT)

The Infrared Telescope (IRT) experiment, flown on Spacelab-2, was used to make infrared measurements between 2 and 120 microns. The objectives were multidisciplinary in nature with astrophysical goals of mapping the diffuse cosmic emission and extended infrared sources and technical goals of measuring the induced Shuttle environment, studying properties of superfluid helium in space, and testing various infrared telescope system designs. Astrophysically, new data were obtained on the structure of the Galaxy at near-infrared wavelengths. A summary of the large scale diffuse near-infrared observations of the Galaxy by the IRT is presented, as well as a summary of the preliminary results obtained from this data on the structure of the galactic disk and bulge. The importance of combining CO and near-infrared maps of similar resolution to determine a 3-D model of galactic extinction is demonstrated. The IRT data are used, in conjunction with a proposed galactic model, to make preliminary measurements of the global scale parameters of the Galaxy. During the mission substantial amounts of data were obtained concerning the induced Shuttle environment. An experiment was also performed to measure spacecraft glow in the IR.

Fazio, Giovanni G.↗

NASA NTRS1989

Advances in computational design and analysis of airbreathing propulsion systems

The development of commercial and military aircraft depends, to a large extent, on engine manufacturers being able to achieve significant increases in propulsion capability through improved component aerodynamics, materials, and structures. The recent history of propulsion has been marked by efforts to develop computational techniques that can speed up the propulsion design process and produce superior designs. The availability of powerful supercomputers, such as the NASA Numerical Aerodynamic Simulator, and the potential for even higher performance offered by parallel computer architectures, have opened the door to the use of multi-dimensional simulations to study complex physical phenomena in propulsion systems that have previously defied analysis or experimental observation. An overview of several NASA Lewis research efforts is provided that are contributing toward the long-range goal of a numerical test-cell for the integrated, multidisciplinary design, analysis, and optimization of propulsion systems. Specific examples in Internal Computational Fluid Mechanics, Computational Structural Mechanics, Computational Materials Science, and High Performance Computing are cited and described in terms of current capabilities, technical challenges, and future research directions.

Klineberg, John M.↗

NASA NTRS1989

The critical role of aerodynamic heating effects in the design of hypersonic vehicles

Hypersonic vehicles operate in a hostile aerothermal environment, which has a significant impact on their aerothermostructural performance. Significant coupling occurs between the aerodynamic flow field, structural heat transfer, and structural response, creating a multidisciplinary interaction. The critical role of aerodynamic heating effects in the design of hypersonic vehicles is identified with an example of high localized heating on an engine-cowl leading edge. Recent advances is integrated fluid-thermal-structural finite-element analyses are presented.

Wieting, Allan R.↗

NASA NTRS1989

On developing the local research environment of the 1990s - The Space Station era

A requirements analysis for the Space Station's polar platform data system has been performed. Based upon this analysis, a cluster, layered cluster, and layered-modular implementation of one specific module within the Eos Data and Information System (EosDIS), an active data base for satellite remote sensing research has been developed. It is found that a distributed system based on a layered-modular architecture and employing current generation work station technologies has the requisite attributes ascribed by the remote sensing research community. Although, based on benchmark testing, probabilistic analysis, failure analysis and user-survey technique analysis, it is found that this architecture presents some operational shortcomings that will not be alleviated with new hardware or software developments. Consequently, the potential of a fully-modular layered architectural design for meeting the needs of Eos researchers has also been evaluated, concluding that it would be well suited to the evolving requirements of this multidisciplinary research community.

Chase, Robert↗

NASA NTRS1989

Recent activities within the aeroservoelasticity branch at the NASA Langley Research Center

The objective of research in aeroservoelasticity at the NASA Langley Research Center is to enhance the modeling, analysis, and multidisciplinary design methodologies for obtaining multifunction digital control systems for application to flexible flight vehicles. Recent accomplishments are discussed, and a status report on current activities within the Aeroservoelasticity Branch is presented. In the area of modeling, improvements to the Minimum-State Method of approximating unsteady aerodynamics are shown to provide precise, low-order aeroservoelastic models for design and simulation activities. Analytical methods based on Matched Filter Theory and Random Process Theory to provide efficient and direct predictions of the critical gust profile and the time-correlated gust loads for linear structural design considerations are also discussed. Two research projects leading towards improved design methodology are summarized. The first program is developing an integrated structure/control design capability based on hierarchical problem decomposition, multilevel optimization and analytical sensitivities. The second program provides procedures for obtaining low-order, robust digital control laws for aeroelastic applications. In terms of methodology validation and application the current activities associated with the Active Flexible Wing project are reviewed.

Noll, Thomas↗

NASA NTRS1988

Satellite altimetry - Observing ocean variability from space

The technique of satellite altimetry is discussed. The complexity of the procedure for attaining highly accurate measurements of the sea level, and the need for a multidisciplinary approach are emphasized. Progress in oceanographic research is reviewed, with the emphasis on results from Skylab and the GEOS-3 missions, as well as from Seasat whose altimeter was the first one designed for oceanographic applications. The challanges that lie ahead, including improving the overall measurement accuracy of altimeter observations, and the development of new techniques for utilizing the altimeter data, are formulated. Future plans for the satellite altimeter systems, Topex/Poseidon and ERS-1.

Fu, Lee-Leung↗

NASA NTRS1990

Aeronautical facility requirements into the 2,000's

This paper delineates and speculates upon aeronautical systems, trends, and requirements into the 2,000's and indicates ground facility capability enhancements which are needed to support these devlopments. New facility capabilities required include (1) higher Reynolds number at low speeds especially for the high-lift and vortex hazard problems, (2) low-disturbance, high-speed aerodynamic and hypersonic propulsion facilities for transition and mixing studies, (3) large-scale and relatively long test-time hypersonic propulsion tunnels to allow multidisciplinary integration, (4) a large-scale, high-speed acoustics facility for en route noise minimization, (5) a large-scale ballistic range for planetary entry studies, and (6) development of advanced (full simultaneous 3-space and time) nonintrusive instrumentation for CFD transition/turbulence modeling/code validation and interacting flow physics determination.

Beach, H. L., Jr.↗

NASA NTRS1990

Space Station Freedom viewed as a 'tight building'

The Space Station Freedom (SSF), with a 30-year projected lifetime and a completely closed-loop Environmental Control and Life Support System (ECLSS), is perhaps the ultimate 'tight building'. Recognizing the potential for the development of 'tight building syndrome' (TBS), and initiating actions to minimize possible TBS occurrences on SSF, requires a multidisciplinary approach that begins with appropriate design concerns and ends with detection and control measures on board SSF. This paper presents a brief summary of current experience with TBS on earth. Air contamination, including volatile organic compounds and microorganisms, is the focus of the discussion. Preventive steps to avoid TBS, control of environmental factors that may lead to TBS, and use of real-time instrumentation for the detection of potential causes of TBS are also outlined.

Limero, Thomas F.↗

NASA NTRS1990

Lunar astronomical observatories - Design studies

The best location in the inner solar system for the grand observatories of the 21st century may be the moon. A multidisciplinary team including university students and faculty in engineering, astronomy, physics, and geology, and engineers from industry is investigating the moon as a site for astronomical observatories and is doing conceptual and preliminary designs for these future observatories. Studies encompass lunar facilities for radio astronomy and astronomy at optical, ultraviolet, and infrared wavelengths of the electromagnetic spectrum. Although there are significant engineering challenges in design and construction on the moon, the rewards for astronomy can be great, such as detection and study of earth-like planets orbiting nearby stars, and the task for engineers promises to stimulate advances in analysis and design, materials and structures, automation and robotics, foundations, and controls. Fabricating structures in the reduced-gravity environment of the moon will be easier than in the zero-gravity environment of earth orbit, as Apollo and space-shuttle missions have revealed. Construction of observatories on the moon can be adapted from techniques developed on the earth, with the advantage that the moon's weaker gravitational pull makes it possible to build larger devices than are practical on earth.

Johnson, Stewart W.↗

NASA NTRS1990

Assessing the feasibility, cost, and utility of developing models of human performance in aviation

The purpose of the effort outlined in this briefing was to determine whether models exist or can be developed that can be used to address aviation automation issues. A multidisciplinary team has been assembled to undertake this effort, including experts in human performance, team/crew, and aviation system modeling, and aviation data used as input to such models. The project consists of two phases, a requirements assessment phase that is designed to determine the feasibility and utility of alternative modeling efforts, and a model development and evaluation phase that will seek to implement the plan (if a feasible cost effective development effort is found) that results from the first phase. Viewgraphs are given.

Stillwell, William↗

NASA NTRS1990

Contents of the NASA ocean data system archive, version 11-90

The National Aeronautics and Space Administration (NASA) Ocean Data System (NODS) archive at the Jet Propulsion Laboratory (JPL) includes satellite data sets for the ocean sciences and global-change research to facilitate multidisciplinary use of satellite ocean data. Parameters include sea-surface height, surface-wind vector, sea-surface temperature, atmospheric liquid water, and surface pigment concentration. NODS will become the Data Archive and Distribution Service of the JPL Distributed Active Archive Center for the Earth Observing System Data and Information System (EOSDIS) and will be the United States distribution site for Ocean Topography Experiment (TOPEX)/POSEIDON data and metadata.

Smith, Elizabeth A.↗

NASA NTRS1990

West Antarctic Ice Sheet Initiative. Volume 1: Science and Implementation Plan

The Science and Implementation Plan of the West Antarctic Ice Sheet Initiative (WAIS) is described. The goal of this initiative is the prediction of the future behavior of this ice sheet and an assessment of its potential to collapse, rapidly raising global sea level. The multidisciplinary nature of WAIS reflects the complexity of the polar ice sheet environment. The project builds upon past and current polar studies in many fields and meshes with future programs of both the U.S. and other countries. Important tasks in each discipline are described and a coordinated schedule by which the majority of these tasks can be accomplished in 5 years is presented. The companion report (Volume 2) contains seven discipline review papers on the state of knowledge of Antarctica and opinions on how that knowledge must be increased to attain the WAIS goal.

Bindschadler, Robert A.↗

NASA NTRS1991

Intelligent control based on fuzzy logic and neural net theory

In the conception and design of intelligent systems, one promising direction involves the use of fuzzy logic and neural network theory to enhance such systems' capability to learn from experience and adapt to changes in an environment of uncertainty and imprecision. Here, an intelligent control scheme is explored by integrating these multidisciplinary techniques. A self-learning system is proposed as an intelligent controller for dynamical processes, employing a control policy which evolves and improves automatically. One key component of the intelligent system is a fuzzy logic-based system which emulates human decision making behavior. It is shown that the system can solve a fairly difficult control learning problem. Simulation results demonstrate that improved learning performance can be achieved in relation to previously described systems employing bang-bang control. The proposed system is relatively insensitive to variations in the parameters of the system environment.

Lee, Chuen-Chien↗

NASA NTRS1991

STARS: An integrated general-purpose finite element structural, aeroelastic, and aeroservoelastic analysis computer program

The details of an integrated general-purpose finite element structural analysis computer program which is also capable of solving complex multidisciplinary problems is presented. Thus, the SOLIDS module of the program possesses an extensive finite element library suitable for modeling most practical problems and is capable of solving statics, vibration, buckling, and dynamic response problems of complex structures, including spinning ones. The aerodynamic module, AERO, enables computation of unsteady aerodynamic forces for both subsonic and supersonic flow for subsequent flutter and divergence analysis of the structure. The associated aeroservoelastic analysis module, ASE, effects aero-structural-control stability analysis yielding frequency responses as well as damping characteristics of the structure. The program is written in standard FORTRAN to run on a wide variety of computers. Extensive graphics, preprocessing, and postprocessing routines are also available pertaining to a number of terminals.

Gupta, Kajal K.↗