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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

[NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 2:] External Information Sources and aerospace R&D: The use and importance of technical reports by US aerospace engineers and scientists

This paper formulates and studies two propositions. Proposition 1 states that information that is external to the aerospace organization tends to be used less than internal sources of information; the more geographically removed the information is from the organization, the less likely it is to be used. Proposition 2 states that of the various sociometric variables assumed to influence the use of an information channel or source, perceived accessibility exerts the greatest influence. Preliminary analysis based on surveys supports Proposition 1. This analysis does not support Proposition 2, however. Evidence here indicates that reliability and relevance influence the use of an information source more than the idea of perceived accessibility.

Blados, Walter R.↗
NASA NTRS1990

Continuation methods in multiobjective optimization for combined structure control design

A homotopy approach involving multiobjective functions is developed to outline the methods that have evolved for the combined control-structure optimization of physical systems encountered in the technology of large space structures. A method to effect a timely consideration of the control performance prior to the finalization of the structural design involves integrating the control and structural design processes into a unified design methodology that combines the two optimization problems into a single formulation. This study uses the combined optimization problem as a family of weighted structural and control costs. Connections with vector optimizations are described; an analysis of the zero-set of required conditions is made, and a numerical example is given.

Milman, M.↗
NASA NTRS1991

Experiences at Langley Research Center in the application of optimization techniques to helicopter airframes for vibration reduction

A NASA/industry rotorcraft structural dynamics program known as Design Analysis Methods for VIBrationS (DAMVIBS) was initiated at Langley Research Center in 1984 with the objective of establishing the technology base needed by the industry for developing an advanced finite-element-based vibrations design analysis capability for airframe structures. As a part of the in-house activities contributing to that program, a study was undertaken to investigate the use of formal, nonlinear programming-based, numerical optimization techniques for airframe vibrations design work. Considerable progress has been made in connection with that study since its inception in 1985. This paper presents a unified summary of the experiences and results of that study. The formulation and solution of airframe optimization problems are discussed. Particular attention is given to describing the implementation of a new computational procedure based on MSC/NASTRAN and CONstrained function MINimization (CONMIN) in a computer program system called DYNOPT for the optimization of airframes subject to strength, frequency, dynamic response, and fatigue constraints. The results from the application of the DYNOPT program to the Bell AH-1G helicopter are presented and discussed.

Murthy, T. Sreekanta↗
NASA NTRS1991

Experiences at Langley Research Center in the application of optimization techniques to helicopter airframes for vibration reduction

A NASA/industry rotorcraft structural dynamics program known as Design Analysis Methods for VIBrationS (DAMVIBS) was initiated at Langley Research Center in 1984 with the objective of establishing the technology base needed by the industry for developing an advanced finite-element-based vibrations design analysis capability for airframe structures. As a part of the in-house activities contributing to that program, a study was undertaken to investigate the use of formal, nonlinear programming-based, numerical optimization techniques for airframe vibrations design work. Considerable progress has been made in connection with that study since its inception in 1985. This paper presents a unified summary of the experiences and results of that study. The formulation and solution of airframe optimization problems are discussed. Particular attention is given to describing the implementation of a new computational procedure based on MSC/NASTRAN and CONstrained function MINimization (CONMIN) in a computer program system called DYNOPT for the optimization of airframes subject to strength, frequency, dynamic response, and fatigue constraints. The results from the application of the DYNOPT program to the Bell AH-1G helicopter are presented and discussed.

Sreekanta Murthy, T.↗
NASA NTRS1993

Boundary layer flow of air over water on a flat plate

A non-similar boundary layer theory for air blowing over a water layer on a flat plate is formulated and studied as a two-fluid problem in which the position of the interface is unknown. The problem is considered at large Reynolds number (based on x), away from the leading edge. A simple non-similar analytic solution of the problem is derived for which the interface height is proportional to x(sub 1/4) and the water and air flow satisfy the Blasius boundary layer equations, with a linear profile in the water and a Blasius profile in the air. Numerical studies of the initial value problem suggests that this asymptotic, non-similar air-water boundary layer solution is a global attractor for all initial conditions.

Nelson, John↗
NASA NTRS1996

ATTDES: An Expert System for Satellite Attitude Determination and Control

The design, analysis, and flight operations of satellite attitude determintion and attitude control systems require extensive mathematical formulations, optimization studies, and computer simulation. This is best done by an analyst with extensive education and experience. The development of programs such as ATTDES permit the use of advanced techniques by those with less experience. Typical tasks include the mission analysis to select stabilization and damping schemes, attitude determination sensors and algorithms, and control system designs to meet program requirements. ATTDES is a system that includes all of these activities, including high fidelity orbit environment models that can be used for preliminary analysis, parameter selection, stabilization schemes, the development of estimators covariance analyses, and optimization, and can support ongoing orbit activities. The modification of existing simulations to model new configurations for these purposes can be an expensive, time consuming activity that becomes a pacing item in the development and operation of such new systems. The use of an integrated tool such as ATTDES significantly reduces the effort and time required for these tasks.

Mackison, Donald L.↗
NASA NTRS1996

Composite Panel Postbuckling Behavior and General Model of Joints in Composite Structures

The present paper is a final technical report on the research programme NCCW-73 accomplished within co-operation between NASA of the USA and GOSKOMOBORONPROM of Russia in the field of aeronautics. The report contains basic results of studies in two areas, 'Analysis of postbuckling behavior of composite panels' and 'Development of general model of joints in composite structures'; these results were obtained in conformity with requirements of NCCW-73. In addition, consideration is given to some related issues, and proposals for further studies are formulated.

Zamula, G. N.↗
NASA NTRS2002

Quadratic Optimization in the Problems of Active Control of Sound

We analyze the problem of suppressing the unwanted component of a time-harmonic acoustic field (noise) on a predetermined region of interest. The suppression is rendered by active means, i.e., by introducing the additional acoustic sources called controls that generate the appropriate anti-sound. Previously, we have obtained general solutions for active controls in both continuous and discrete formulations of the problem. We have also obtained optimal solutions that minimize the overall absolute acoustic source strength of active control sources. These optimal solutions happen to be particular layers of monopoles on the perimeter of the protected region. Mathematically, minimization of acoustic source strength is equivalent to minimization in the sense of L(sub 1). By contrast. in the current paper we formulate and study optimization problems that involve quadratic functions of merit. Specifically, we minimize the L(sub 2) norm of the control sources, and we consider both the unconstrained and constrained minimization. The unconstrained L(sub 2) minimization is certainly the easiest problem to address numerically. On the other hand, the constrained approach allows one to analyze sophisticated geometries. In a special case, we call compare our finite-difference optimal solutions to the continuous optimal solutions obtained previously using a semi-analytic technique. We also show that the optima obtained in the sense of L(sub 2) differ drastically from those obtained in the sense of L(sub 1).

Loncaric, J.↗
NASA NTRS2004

Injection Characteristics of Non-Swirling and Swirling Annular Liquid Sheets

A simplified mathematical model, based on body-fitted coordinates, is formulated to study the evolution of non-swirling and swirling liquid sheet emanated from an annular nozzle in a quiescent surrounding medium. The model provides predictions of sheet trajectory, thickness and velocity at various liquid mass flow rates and liquid-swirler angles. It is found that a non-swirling annular sheet converges toward its centerline and assumes a bell shape as it moves downstream from the nozzle. The bell radius, and length are more pronounced at higher liquid mass flow rates. The thickness of the non-swirling annular sheet increases while its stream-wise velocity decreases with an increase in mass flow rate. The introduction of swirl results in the formation of a diverging hollow-cone sheet. The hollow-cone divergence from its centerline is enhanced by an increase in liquid mass flow rate or liquid-swirler angle. The hollow- cone sheet its radius, curvature and stream-wise velocity increase while its thickness and tangential velocity decrease as a result of increasing the mass flow rate or liquid-swirler angle. The present results are compared with previous studies and conclusions are drawn.

Harper, Brent↗
NASA NTRS2006

PP after PREVCOM

This viewgraph presentation reviews the recommendations and implications for Planetary Protection (PP) as recomended by the Mars Exploration Program Analysis Group (MEPAG). This study was formulated in 17 recommendations to NASA in a report Preventing the Forward Contamination of Mars (PREVCOM). Particular attention is paid to the recommendation number 5 that states "Require routine collection of phylogenetic data and require systematic archiving of environmental samples from Assembly, Test, and Launch Operations (ATLO) environments and spacecraft."

planetary protection↗
NASA NTRS2007

The Space Infrared Interferometric Telescope (SPIRIT) and its Complementarity to ALMA

We report results of a pre-Formulation Phase study of SPIRIT, a candidate NASA Origins Probe mission. SPIRIT is a spatial and spectral interferometer with an operating wavelength range 25 - 400 microns. SPIRIT will provide sub-arcsecond resolution images and spectra with resolution R = 3000 in a 1 arcmin field of view to accomplish three primary scientific objectives: (1) Learn how planetary systems form from protostellar disks, and how they acquire their chemical organization; (2) Characterize the family of extrasolar planetary systems by imaging the structure in debris disks to understand how and where planets of different types form; and (3) Learn how high-redshift galaxies formed and merged to form the present-day population of galaxies. In each of these science domains, SPIRIT will yield information complementary to that obtainable with the James Webb Space Telescope (JWST)and the Atacama Large Millimeter Array (ALMA), and all three observatories could operate contemporaneously. Here we shall emphasize the SPIRIT science goals (1) and (2) and the mission's complementarity with ALMA.

Leisawitz, Dave↗
NASA NTRS2012

Development and Testing of Molecular Adsorber Coatings

The effect of on-orbit molecular contamination has the potential to degrade the performance of spaceflight hardware and diminish the lifetime of the spacecraft. For example, sensitive surfaces, such as optical surfaces, electronics, detectors, and thermal control surfaces, are vulnerable to the damaging effects of contamination from outgassed materials. The current solution to protect these surfaces is through the use of zeolite coated ceramic adsorber pucks. However, these pucks and its additional complex mounting hardware requirements result in several disadvantages, such as size, weight, and cost related concerns, that impact the spacecraft design and the integration and test schedule. As a result, a new innovative molecular adsorber coating was developed as a sprayable alternative to mitigate the risk of on-orbit molecular contamination. In this study, the formulation for molecular adsorber coatings was optimized using various binders, pigment treatment methods, binder to pigment ratios, thicknesses, and spray application techniques. The formulations that passed coating adhesion and vacuum thermal cycling tests were further tested for its adsorptive capacity. Accelerated molecular capacitance tests were performed in an innovatively designed multi-unit system containing idealized contaminant sources. This novel system significantly increased the productivity of the testing phase for the various formulations that were developed. Work performed during the development and testing phases has demonstrated successful application of molecular adsorber coatings onto metallic substrates, as well as, very promising results for the adhesion performance and the molecular capacitance of the coating. Continued testing will assist in the qualification of molecular adsorber coatings for use on future contamination sensitive spaceflight missions.

Abraham, Nithin↗
NASA NTRS2018

AIST Overview Advanced Information System Technology Fueling Innovation for Earth Observing

One element of NASA's Earth Science Technology Office is the Advanced Information Systems Technology (AIST) Program, which funds information technology development for use in the 5-20 year timeframe. The needs are identified in conjunction with the NASA research and applied sciences communities and discussions with other, forward-looking organizations, such as ESA. AIST projects must have a US lead, but collaborations with non-US organizations are encouraged. The AIST Program focuses on two major thrusts and a small collection of concept studies and solicits both evolutionary and disruptive development projects. One thrust seeks to leverage the emergence of smallsats to create constellations of instruments to examine phenomena that could not be studied before using conventional single-satellite instruments. The second thrust develops re-usable tools to support scientific investigations through the interaction with data. The study projects formulate relevant theory, bleeding-edge concepts or to articulate need statements more clearly for highly advanced work. This talk will describe the research and development funded by the AIST Program.

Little, Michael M.↗
NASA NTRS2019

Assessment of a One-Dimensional Finite Element Charring Ablation Material Response Model for Phenolic-Impregnated Carbon Ablator

In this study, mathematical formulations to model charring ablation problems were numerically implemented using finite element analysis (FEA) with ABAQUS, which account for the material decomposition and progressive surface removal in the heat conduction and the surface energy balance equations. FEA was performed for a one-dimensional model to predict the temperature and ablation histories of a phenolic-impregnated carbon ablator sample (i.e., a common heat shield material for hypersonic vehicles and spacecraft) subjected to oxy-acetylene torch flame (i.e., 0.8 SLPM acetylene gas to 2.7 SLPM oxygen gas). The recovery enthalpy and convective heat transfer coefficient for the ablation model were calculated based on gas compositions and two assumed surface conditions (i.e., equilibrium and frozen). Simulations using the calculated recovery enthalpy and convective heat transfer coefficient resulted in a recession rate of 6.38 times (equilibrium) and 14.08 times (frozen) higher than the experimental data, despite fair agreement of the surface temperature. In addition, the effect of the heat transfer coefficient was investigated through a steady-state ablation analysis. The results of the analysis indicate that there is not one single value for the heat transfer coefficient that would allow the prediction to match both measured recession rate and surface temperature. Possible reasons for such an inconsistency are provided and discussed.

Thermal Protection System↗
NASA NTRSDate not supplied

Design and Comparison of Lunar Sample Return Options

Returning lunar samples to earth is a high priority for NASA in order to better understand Lunar Geology, Lunar formation, and potential resource utilization. Core samples of frozen volatiles from permanently shadowed regions are sought after, but require intensive cryogenic cooling to preserve. Returning samples to Earth using the Orion capsule is restrictive for moderate amounts of mass/volume and thus alternate means of transport are investigated in this paper. The trade-space of potential options includes varying: sample mass amount, sample containment conditions, transfer path from Lunar surface to Earth surface, and various vehicle system trades. An integrated solver is applied with parametric estimators and known system heuristics to effectively estimate size, mass, and power of various subsystems. Modeled subsystems include sample containment, EDL technologies(heat shield, parachute, recovery), power, thermal, avionics, structures, and propulsive systems. Transfer path options include various trajectory options, transfer methods, staging points, and vehicle staging options. A Design of Experiments was conducted to explore the tradespace, to identify sensitivities, and to identify promising designs. Results are detailed for various stakeholder objectives including total mass, sample mass, science return, architecture impacts, and operational flexibility.

Lunar outpost↗
NASA NTRS1983

Polyimides formulated from a partially fluorinated diamine for aerospace tribological applications

Preliminary tribological studies on polyimides formulated from the diamine 2,2-bis 4-(4-aminophenoxy)phenyl hexafluorapane (4-BDAF) indicate that polyimides formulated from this diamine have excellent potential for high temperature tribological applications. The dianhydrides used to make the polyimides were pyromellitic (PMDA) and benzophenonetetracarboxylic acid (BTDA). Friction and wear studies at 25 and 200 C indicate that polyimides formulated using 50 mole percent of the PMDA dianhydride and 50 mole percent of the BTDA dianhydride perform better than polyimides formulated solely with the BTDA dianhydride. Graphite fiber reinforced polyimide composites were formulated with the polyimide made from the BTDA dianhydride, both graphitic and non-graphitic fibers were evaluated. Graphitic fibers produced better tribological results, since thin, flowing, "layer-like' transfer films were produced which did not build-up with long sliding durations. Non-graphitic fibers did not produce this type of transfer.

Fusaro, R. L.↗
NASA NTRS1984

Polyimides formulated from a partially fluorinated diamine for aerospace tribological applications

Preliminary pribological studies on polyimides formulated from the diamine 2,2-bis 4-(4-aminophenoxy)phenyl hexafluoropane (4-BDAF) indicate that polyimides formulated from this diamine have excellent potential for high temperature tribological applications. The dianhydrides used to make the polyimides were pyromellitic (PMDA) and benzophenonetetracarboxylic acid (BTDA). Friction and wear studies at 25 and 200 C indicate that polyimides formulated using 50 mole percent of the PMDA dianhydride and 50 mole percent of the BTDA dianhydride perform better than polyimides formulated solely with the BTDA dianhydride. Graphite fiber reinforced polyimide composites were formulated with the polyimide made from the BTDA dianhydride and both graphitic and non-graphitic fibers were evaluated. Graphitic fibers produced better tribological results, since thin, flowing, 'layer-like' transfer films were produced which did not build up with long sliding durations. Non-graphitic fibers did not produce this type of transfer. Previously announced in STAR as N83-22423

Fusaro, R. L.↗