SEARCH · Engineering Papers

Results for “flexible generation”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13

All sources NASA NTRS DOE OSTI

NASA NTRS2018

Synergistic and Collaborative Development Strategies for FV3 Powered Next Generation Unified Global Modeling System

The GFDL (Geophysical Fluid Dynamics Laboratory, NOAA - National Oceanic and Atmospheric Administration) Finite-Volume Cubed-Sphere Dynamical Core (FV3) is a scalable and flexible dynamical core capable of both hydrostatic and non-hydrostatic atmospheric simulations. FV3 has been chosen as the dynamical core for the Next Generation Global Prediction System project (NGGPS), designed to upgrade the current NCEP (National Centers for Environmental Prediction, NOAA) operational Global Forecast System (GFS) to run as a unified, fully-coupled system in NOAA's Environmental Modeling System infrastructure. FV3 dynamic core has a long history of serving as the main engine for global atmospheric models at various Government and Academic Research Laboratories including NOAA: GFDL Climate Modeling Suite (AM4 (Atmosphere Modeling 4), CM4 (Climate Model 4) ESM4 (Earth System Model 4), Hiram (HIgh Resolution Atmospheric Model)); NASA: GMAO (Global Modeling and Assimilation Office) Goddard Earth Observing System Model (GEOS); and NCAR (National Center for Atmospheric Research) Community Earth System Model (CESM). The three primary stakeholders in FV3 (GFDL, GMAO, EMC (Environmental Modeling Center - NOAA)) have embarked on synergistic and collaborative strategies with focus on the advancement of non-hydrostratic dynamic core, physics, chemistry, and data assimilation efforts, leveraging collective strengths of each of the partnering agencies. This talk presents the ongoing plans for model advancements at GFDL, GMAO and EMC, with special emphasis on contributions towards developing community based unified global modeling system for operational and research applications at respective organizations. Future plans include extending the collaborations to the development of earth system components including GMAO's aerosol chemistry models (GOCART/MAM (Goddard Chemistry Aerosol Radiation and Transport / Modal Aerosol Model)), Land Information System (LIS), and advanced data assimilation techniques; and GFDL's Modular Ocean Model (MOM) and Sea Ice Simulator (SIS) for transition to operations at NCEP.

Putman, William↗

NASA NTRS1983

Modular design attitude control system

The problem of applying modular attitude control to a rigid body - flexible suspension model of a flexible spacecraft with some state variables inaccessible was addressed by developing a sequence of single axis models and generating a series of reduced state linear observers of minimum order to reconstruct those scalar variables that were inaccessible. The specific single axis models treated consisted of two, three and four rigid bodies, respectively, interconnected by a flexible shaft passing through the mass centers of the bodies. Reduced state linear observers of all orders up to one less than the total number of scalar state variables were generated for each of the three single axis models cited.

Chichester, F. D.↗

NASA NTRS1986

Brush-Type Connectors for Thermoelectric Elements

Wire brushes used to connect positive and negative legs of semiconductor thermoelectric generators to power leads and heat sources and sinks. Brushes are flexible thermal and electrical conductors that readily accommodate expansion and contraction of legs with changing temperature. Thus, direct conductive coupling between heat source and sink allowed, in contrast to older and less efficient method of having to couple radiatively to accommodate thermal expansion.

Wood, C.↗

NASA NTRS1985

Approach for service life extension of explosive devices for aircraft escape systems

Service life extension of explosive devices used in aircraft escape systems can achieve considerable savings. An overall approach is needed to challenge the logic of explosive component service extension from design to removal from service for evaluation. The purpose of the effort described in this paper was to develop a service-extension approach on explosive devices used in aircraft systems, supported by actual testing of representative candidate devices, to evaluate quantitatively the effects of service, age, and degradation, and allow responsible, conservative service life determinations. Evaluated were five explosive components: rigid and flexible explosive transfer lines, one-way transfers, flexible linear shaped charges, and initiation handles. The service extension approach generated in this effort is summarized by eight recommendations.

Bement, L. J.↗

NASA NTRS1987

A multidomain global modeling technique for analysis of Space Shuttle main engine

A multidomain global modeling technique is presented. The purpose of this multidomain methodology is to simultaneously analyze the three-dimensional compressible flow field in Space Shuttle main engine components. This technique provides flexibility and modularity for individual domain and also simplifies the grid generation task for each domain. A two-way coupling procedure is adopted for exchanging interface boundary conditions. This algorithm which requires that the adjacent domains share an overlapping grid slab, is fully conservative and implicit. For non-matching grid systems and for non-overlapping interfaces, an interpolation and/or extrapolation procedure is used when transferring the interface boundary conditions at the adjacent domains. To maintain overall conservation, a flux correction method is subsequently used. The coupling procedure was verified by modeling several geometries with features similar to SSME components. Satisfactory results for all test cases were obtained. Finally, this algorithm has been applied to the SSME flow simulation.

Tam, L. T.↗

NASA NTRS1992

Integrated geometry and grid generation system for complex configurations

A grid generation system was developed that enables grid generation for complex configurations. The system called ICEM/CFD is described and its role in computational fluid dynamics (CFD) applications is presented. The capabilities of the system include full computer aided design (CAD), grid generation on the actual CAD geometry definition using robust surface projection algorithms, interfacing easily with known CAD packages through common file formats for geometry transfer, grid quality evaluation of the volume grid, coupling boundary condition set-up for block faces with grid topology generation, multi-block grid generation with or without point continuity and block to block interface requirement, and generating grid files directly compatible with known flow solvers. The interactive and integrated approach to the problem of computational grid generation not only substantially reduces manpower time but also increases the flexibility of later grid modifications and enhancements which is required in an environment where CFD is integrated into a product design cycle.

Akdag, Vedat↗

NASA NTRS2004

The Vision for Space Exploration

With last year's budget, NASA released a new Strategic Plan outlining a new approach to space exploration using a 'building block' strategy to explore scientifically valuable destinations across our solar system. At the same time that we released the Strategic Plan, our Nation and the NASA family also suffered the loss of the seven brave astronauts aboard the Space Shuttle Columbia. The report of the Columbia Accident Investigation Board emphasized the need for a clearer direction from which to drive NASA's human exploration agenda. On January 14, 2004, the President articulated a new vision for space exploration. You hold in your hands a new, bolder framework for exploring our solar system that builds upon the policy that was announced by the President after months of careful deliberations within the Administration. This plan does not undertake exploration merely for the sake of adventure, however exciting that may be, but seeks answers to profound scientific and philosophical questions, responds to recent discoveries, will put in place revolutionary technologies and capabilities for the future, and will genuinely inspire our Nation, the world, and the next generation. Our aim is to explore in a sustainable, affordable, and flexible manner. We believe the principles and roadmap set down in this document will stand the test of time. Its details will be subject to revision and expansion as new discoveries are made, new technologies are applied, and new challenges are met and overcome. This plan is guided by the Administration's new space exploration policy, 'A Renewed Spirit of Discovery: The President's Vision for U.S. Space Exploration,' a copy of which is provided on the following pages. NASA is releasing this plan simultaneously with NASA's FY 2005 Budget Justification. This plan is fiscally responsible, consistent with the Administration s goal of cutting the budget deficit in half within the next five years. I cannot overstate how much NASA will change in the coming years as this plan is implemented. I also cannot overstate how profound the rewards will be on this new course. With the support of Congress, the science community, the NASA civil and contractor workforce, and most importantly, the American public, we will embark on this very exciting future. When Christopher Columbus made his voyages across the Atlantic in the 15th and 16th centuries, his ships carried the inscription 'Following the light of the sun, we left the Old World.' I look forward to joining you as we follow the light of the planets and the stars into the new worlds of the 21st century.

Source record↗

NASA NTRS2008

On-Orbit Multi-Field Wavefront Control with a Kalman Filter

A document describes a multi-field wavefront control (WFC) procedure for the James Webb Space Telescope (JWST) on-orbit optical telescope element (OTE) fine-phasing using wavefront measurements at the NIRCam pupil. The control is applied to JWST primary mirror (PM) segments and secondary mirror (SM) simultaneously with a carefully selected ordering. Through computer simulations, the multi-field WFC procedure shows that it can reduce the initial system wavefront error (WFE), as caused by random initial system misalignments within the JWST fine-phasing error budget, from a few dozen micrometers to below 50 nm across the entire NIRCam Field of View, and the WFC procedure is also computationally stable as the Monte-Carlo simulations indicate. With the incorporation of a Kalman Filter (KF) as an optical state estimator into the WFC process, the robustness of the JWST OTE alignment process can be further improved. In the presence of some large optical misalignments, the Kalman state estimator can provide a reasonable estimate of the optical state, especially for those degrees of freedom that have a significant impact on the system WFE. The state estimate allows for a few corrections to the optical state to push the system towards its nominal state, and the result is that a large part of the WFE can be eliminated in this step. When the multi-field WFC procedure is applied after Kalman state estimate and correction, the stability of fine-phasing control is much more certain. Kalman Filter has been successfully applied to diverse applications as a robust and optimal state estimator. In the context of space-based optical system alignment based on wavefront measurements, a KF state estimator can combine all available wavefront measurements, past and present, as well as measurement and actuation error statistics to generate a Maximum-Likelihood optimal state estimator. The strength and flexibility of the KF algorithm make it attractive for use in real-time optical system alignment when WFC alone cannot effectively align the system.

Lou, John↗

NASA NTRS2015

Comparison of Computational and Experimental Results for a Transonic Variable-Speed Power-Turbine Blade Operating with Low Inlet Turbulence Levels

A computational assessment of the aerodynamic performance of the midspan section of a variable-speed power-turbine blade is described. The computation comprises a periodic single blade that represents the 2-D Midspan section VSPT blade that was tested in the NASA Glenn Research Center Transonic Turbine Blade Cascade Facility. A commercial, off-the-shelf (COTS) software package, Pointwise and CFD++, was used for the grid generation and RANS and URANS computations. The CFD code, which offers flexibility in terms of turbulence and transition modeling options, was assessed in terms of blade loading, loss, and turning against test data from the transonic tunnel. Simulations were assessed at positive and negative incidence angles that represent the turbine cruise and take-off design conditions. The results indicate that the secondary flow induced at the positive incidence cruise condition results in a highly loaded case and transitional flow on the blade is observed. The negative incidence take-off condition is unloaded and the flow is very two-dimensional. The computational results demonstrate the predictive capability of the gridding technique and COTS software for a linear transonic turbine blade cascade with large incidence angle variation.

turbomachinery↗

NASA NTRS2015

Comparison of Computational and Experimental Results for a Transonic Variable-speed Power-Turbine Blade Operating with Low Inlet Turbulence Levels

rotary wing↗

NASA NTRS1984

Modular design attitude control system

The problem of applying modular attitude control to a rigid body-flexible suspension model of a flexible spacecraft with some state variables inaccessible was addressed by developing a sequence of single axis models and generating a series of reduced state linear observers of minimum order to reconstruct those scalar state variables that were inaccessible. The specific single axis models treated consisted of two, three and four rigid bodies, respectively, interconnected by a flexible shaft passing through the mass centers of the bodies. Reduced state linear observers of all orders up to one less than the total number of scalar state variables were generated for each of the three single axis models cited.

Chichester, F. D.↗

NASA NTRS2004

Flexible Approximation Model Approach for Bi-Level Integrated System Synthesis

Bi-Level Integrated System Synthesis (BLISS) is an approach that allows design problems to be naturally decomposed into a set of subsystem optimizations and a single system optimization. In the BLISS approach, approximate mathematical models are used to transfer information from the subsystem optimizations to the system optimization. Accurate approximation models are therefore critical to the success of the BLISS procedure. In this paper, new capabilities that are being developed to generate accurate approximation models for BLISS procedure will be described. The benefits of using flexible approximation models such as Kriging will be demonstrated in terms of convergence characteristics and computational cost. An approach of dealing with cases where subsystem optimization cannot find a feasible design will be investigated by using the new flexible approximation models for the violated local constraints.

Sobieszczanski-Sobieski, Jaroslaw↗

NASA NTRS1994

Post-flight investigation programmes of recently retrieved solar generators

In 1993 two ESA solar power generators were successfully retrieved from space: EURECA with its 10 panel rigid array in August, after 11 months in a 500 km orbit, and one of the two flexible Hubble Space Telescope (HST) arrays in December, after almost 4 years in a 600 km orbit. Both solar generators are undergoing separate post-flight investigation programs (PFIP). These programs cover investigations of all solar array (SA) components and mechanisms. Since both programs have much in common, most of the component and material investigations are the same. Extremely valuable information on numerous essential subjects, such as atomic oxygen, radiation, meteoroid and space debris environment resulting damage, low cycle fatigue, material degradation, etc. are expected to be obtained for both types of arrays. We will also be able to explain and understand the anomalies experienced on both solar arrays in orbit. The paper will outline both post-flight investigation programs and will concentrate on reporting the first results and findings.

Grelach, Lothar↗

NASA NTRS1999

Manipulating Liquids With Acoustic Radiation Pressure Phased Arrays

High-intensity ultrasound waves can produce the effects of "Acoustic Radiation Pressure" (ARP) and "acoustic streaming." These effects can be used to propel liquid flows and to apply forces that can be used to move or manipulate floating objects or liquid surfaces. NASA's interest in ARP includes the remote-control agitation of liquids and the manipulation of bubbles and drops in liquid experiments and propellant systems. A high level of flexibility is attained by using a high-power acoustic phased array to generate, steer, and focus a beam of acoustic waves. This is called an Acoustic Radiation Pressure Phased Array, or ARPPA. In this approach, many acoustic transducer elements emit wavelets that converge into a single beam of sound waves. Electronically coordinating the timing, or "phase shift," of the acoustic waves makes it possible to form a beam with a predefined direction and focus. Therefore, a user can direct the ARP force at almost any desired point within a liquid volume. ARPPA lets experimenters manipulate objects anywhere in a test volume. This flexibility allow it to be used for multiple purposes, such as to agitate liquids, deploy and manipulate drops or bubbles, and even suppress sloshing in spacecraft propellant tanks.

Oeftering, Richard C.↗

NASA NTRS2004

Flexible Microsensor Array for the Monitoring and Control of Plant Growth System

Testing for plant experiments in space has begun to explore active nutrient delivery concepts in which water and nutrients are replenished on a continuous basis for long-term growth. The goal of this study is to develop a novel microsensor array to provide information on the dissolved oxygen environment in the plant root zone for the optimum control of hydroponics and solid substrate plant cultivation systems in the space environment. Miniaturized polarographic dissolved oxygen sensors have been designed and fabricated on a flexible Kapton (trademark) (polyimide) substrate. Two capabilities of the new microsensor array were explored. First, measurements of dissolved oxygen in the plant root zone in hydroponics and solid substrate culture systems were made. The microsensor array was fabricated on a flexible substrate, and then cut out into a mesh type to make a suspended array that could be placed either in a hydroponics system or in a solid substrate cultivation system to measure the oxygen environments. Second, the in situ self-diagnostic and self-calibration capability (two-point for oxygen) was adopted by dynamically controlling the microenvironment in close proximity to the microsensors. With a built-in generating electrode that surrounds the microsensor, two kinds of microenvironments (oxygen-saturated and oxygen-depleted phases) could be established by water electrolysis depending on the polarity of the generating electrode. The unique features of the new microsensor array (small size, multiple sensors, flexibility and self-diagnosis) can have exceptional benefits for the study and optimization of plant cultivation systems in both terrestrial and microgravity environments. The in situ self-diagnostic and self-calibration features of the microsensor array will also enable continuous verification of the operability during entire plant growth cycles. This concept of automated control of a novel chemical monitoring system will minimize crew time required for maintenance, as well as reduce volume, mass, and power consumption by eliminating bulky diagnosis systems including calibrant (fluid and gas) reservoir and flow system hardware.

Kim, Chang-Soo↗

NASA NTRS2008

Novel Low-Temperature Poss-Containing Siloxane Elastomers

One route to increased aircraft performance is through the use of flexible, shape-changeable aerodynamics effectors. However, state of the art materials are not flexible or durable enough over the required broad temperature range. Mixed siloxanes were crosslinked by polyhedral oligomeric silsesquioxanes (POSS) producing novel materials that remained flexible and elastic from -55 to 94 C. POSS molecules were chemically modified to generate homogeneous distributions within the siloxane matrix. High resolution scanning electron microscope (HRSEM) images indicated homogenous POSS distribution up to 0.8 wt %. Above the solubility limit, POSS aggregates could be seen both macroscopically and via SEM (approx.60-120 nm). Tensile tests were performed to determine Young s modulus, tensile strength, and elongation at break over the range of temperatures associated with transonic aircraft use (-55 to 94 C; -65 to 200 F). The siloxane materials developed here maintained flexibility at -55 C, where previous candidate materials failed. At room temperature, films could be elongated up to 250 % before rupturing. At -55 and 94 C, however, films could be elongated up to 400 % and 125 %, respectively.

Belcher, Marcus A.↗

NASA NTRS2015

Thin, Flexible IMM Solar Array

NASA needs solar arrays that are thin, flexible, and highly efficient; package compactly for launch; and deploy into large, structurally stable high-power generators. Inverted metamorphic multijunction (IMM) solar cells can enable these arrays, but integration of this thin crystalline cell technology presents certain challenges. The Thin Hybrid Interconnected Solar Array (THINS) technology allows robust and reliable integration of IMM cells into a flexible blanket comprising standardized modules engineered for easy production. The modules support the IMM cell by using multifunctional materials for structural stability, shielding, coefficient of thermal expansion (CTE) stress relief, and integrated thermal and electrical functions. The design approach includes total encapsulation, which benefits high voltage as well as electrostatic performance.

Walmsley, Nicholas↗

NASA NTRS1977

A lightweight solar array study

A sample module was assembled to model a portion of a flexible extendable solar array, a type that promises to become the next generation of solar array design. The resulting study of this module is intended to provide technical support to the array designer for lightweight component selection, specifications, and tests. Selected from available lightweight components were 127-micron-thick wrap-around contacted solar cells, 34- micron-thick sputtered glass covers, and as a substrate a 13-micron-thick polyimide film clad with a copper printed circuit. Each component displayed weaknesses. The thin solar cells had excessive breakage losses. Sputtered glass cover adhesion was poor, and the covered cell was weaker than the cell uncovered. Thermal stresses caused some cell delamination from the model solar array substrate.

Josephs, R. H.↗