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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 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Efficiency trade-offs of steady-state methods using FEM and FDM

The efficiency characteristics of finite element and finite difference approximations for the steady-state solution of the Navier-Stokes equations are examined. The finite element method discussed is a standard Galerkin formulation of the incompressible, steady-state Navier-Stokes equations. The finite difference formulation uses simple centered differences that are O(delta x-squared). Operation counts indicate that a rapidly converging Newton-Raphson-Kantorovitch iteration scheme is generally preferable over a Picard method. A split NOS Picard iterative algorithm for the finite difference method was most efficient.

Gartling, D. K.↗
NASA NTRS1979

Near-term hybrid vehicle program, phase 1. Appendix B: Design trade-off studies

The relative attractiveness of various hybrid/electric power train configurations and electrical and mechanical drive-line components was studied. The initial screening was concerned primarily with total vehicle weight and economic factors and identified the hybrid power train combinations which warranted detailed evaluation over various driving cycles. This was done using a second-by-second vehicle simulation program which permitted the calculations of fuel economy, electricity usage, and emissions as a function of distance traveled in urban and highway driving. Power train arrangement possibilities were examined in terms of their effect on vehicle handling, safety, serviceability, and passenger comfort. A dc electric drive system utilizing a separately excited motor with field control and battery switching was selected for the near term hybrid vehicle. Hybrid vehicle simulations showed that for the first 30 mi (the electric range of the vehicle) in urban driving, the fuel economy was 80 mpg using a gasoline engine and 100 mpg using a diesel engine. In urban driving the hybrid would save about 75% of the fuel used by the conventional vehicle and in combined urban/highway driving the fuel saving is about 50%.

Source record↗
NASA NTRS1980

Phase 1 of the near term hybrid passenger vehicle development program. Appendix B: Trade-off studies, volume 1

Tradeoff study activities and the analysis process used are described with emphasis on (1) review of the alternatives; (2) vehicle architecture; and (3) evaluation of the propulsion system alternatives; interim results are presented for the basic hybrid vehicle characterization; vehicle scheme development; propulsion system power and transmission ratios; vehicle weight; energy consumption and emissions; performance; production costs; reliability, availability and maintainability; life cycle costs, and operational quality. The final vehicle conceptual design is examined.

Traversi, M.↗
NASA NTRS1979

Phase 1 of the near term hybrid passenger vehicle development program. Appendix B: Trade-off studies. Volume 2: Appendices

The SPEC '78 computer program which consists of mathematical simulations of any vehicle component and external environment is described as are configuration alternatives for the propulsion system. Preliminary assessments of the fundamental characteristics of the lead-acid and sodium-sulfur batteries are included and procedures are given for estimating the cost of a new vehicle in mass production.

Traversi, M.↗
NASA NTRS1980

Space radiator trade studies for the 25 kW Power System

Advanced radiator designs which will survive the meteoroid hazard of near earth orbit for five years are evaluated for the 25 kW Power System. Weight comparisons of heat pipe radiators and pumped fluid radiators incorporating meteoroid bumpers are presented for the initial 25 kW Power System and growth versions to 250 kW. The heat pipe concept is enhanced by a new design of the thermal interface between the heat pipe and coolant loop. The results show small weight differences between the advanced heat pipe and pumped fluid concepts for heat loads up to about 50 kW. The heat pipe panels have a weight advantage for larger heat loads.

Howell, H. R.↗
NASA NTRS1978

Preliminary design trade-offs for a multi-mission stored cryogen cooler

Preliminary design studies were performed for a multi-mission solid cryogen cooler having a wide range of application for both the shuttle sortie and free flyer missions. This multi-mission cooler (MMC) is designed to be utilized with various solid cryogens to meet a wide range of instrument cooling from 10 K (with solid hydrogen) to 90 K. The baseline cooler utilizes two stages of solid cryogen and incorporates an optional, higher temperature third stage which is cooled by either a passive radiator or a thermoelectric cooler. The MMC has an interface which can accommodate a wide variety of instrument configurations. A shrink fit adapter is incorporated which allows a drop-in instrument integration. The baseline design provides cooling of approximately 1 watt over a 60 to 100 K temperature range and about 0.5 watts from 15 to 60 K for a one year lifetime. For low cooling loads and with use of the optional radiator shield, cooling lifetimes as great as 8 years are predicted.

Sherman, A.↗
NASA NTRS1979

Impact of improved information on the structure of world grain trade

The benefits to be derived by the United States from improvements in global grain crop forecasting capability are discussed. The improvements in forecasting accuracy, which are a result of the use of satellite technology in conjunction with existing ground based estimating procedures are described. The degree of forecasting accuracy to be obtained from satellite technology is also examined. Specific emphasis is placed on wheat production in seven countries/regions: the United States; Canada; Argentina; Australia; Western Europe; the USSR; and all other countries in a group.

Source record↗
NASA NTRS1979

Natural laminar flow airfoil analysis and trade studies

An analysis of an airfoil for a large commercial transport cruising at Mach 0.8 and the use of advanced computer techniques to perform the analysis are described. Incorporation of the airfoil into a natural laminar flow transport configuration is addressed and a comparison of fuel requirements and operating costs between the natural laminar flow transport and an equivalent turbulent flow transport is addressed.

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NASA NTRS1982

Evolutionary space platform concept study. Volume 2, part A: SASP special emphasis trade studies

Efforts are in progress to define an approach to provide a simple and cost effective solution to the problem of long duration space flight. This approach involves a Space Platform in low Earth orbit, which can be tended by the Space Shuttle and which will provide, for extended periods of time, stability, utilities and access for a variety of replaceable payloads. The feasibility of an evolutionary space system which would cost effectively support unmanned payloads in groups, using a Space Platform which provides centralized basic subsystems is addressed.

Source record↗
NASA NTRS1983

Nickel hydrogen/nickel cadmium battery trade studies

Nickel Hydrogen cell and battery technology has matured to the point where a real choice exists between Nickel Hydrogen and Nickel Cadmium batteries for each new spacecraft application. During the past few years, a number of spacecraft programs have been evaluated at Hughes with respect to this choice, with the results being split about fifty-fifty. The following paragraphs contain criteria which were used in making the battery selection.

Stadnick, S. J.↗
NASA NTRS1983

Space station propulsion system trade study

This study evaluates alternative space station propulsion system options for a range of space station configurational and operational architectures. Space station propulsion requirements ranging from those representative of the first generation space station to those of an advanced space station with a space based OTV are considered. A methodology for comparing the candidate propulsion technologies is developed which considers design/development/qualification and operational costs, system mass, performance, reliability, and other relevant parameters. Advanced propulsion systems are shown to reduce space station costs by providing higher performance but to require a larger front end investment for development and qualification. This study indicates that if the full potential of such systems is to be realized, then low cost implementations of this technology must be developed.

Garrison, P. W.↗
NASA NTRS1983

Control/display trade-off study for single-pilot instrument flight rule operations

The objectives were to determine minimum autopilot functions and displays required to keep pilot workload at an acceptable level; to determine what constitutes an acceptable level of workload; to identify critical tasks; and to suggest specific experiments required to refine conclusions. It was determined that workload relief is derived from basic stability augmentation; that complex autopilots can lead to serious blunders; and that displays need to enhance positional awareness and minimize the likelihood of false hypothesis.

Hoh, R.↗
NASA NTRS1982

Design trade-offs for a multispectral linear array (MLA) instrument

The NASA Landsat program with imagery produced by the Multispectral Scanner has been thoroughly successful. The second generation of Landsat is represented by the Thematic Mapper, while the MLA sensor belongs to a third generation. It is pointed out that the strength of the MLA concept emanates from the pushbroom image-formation approach, which offers some fundamental improvements over opto-mechanically scanned instruments. The increased dwell time of the MLA sensor can be employed to improve signal-to-noise, spectral resolution, and spatial resolution simultaneously. Problems regarding design tradeoffs are considered, taking into account instrument sizing, configuration tradeoffs, optical design tradeoffs, aspects of spectral separation and registration, and radiometric accuracy and calibration tradeoffs. A description is provided of the instrument concept to which the design tradeoffs have led.

Mika, A. M.↗
NASA NTRS1982

An engine trade study for a supersonic STOVL fighter-attack aircraft, volume 1

The best main engine for an advanced STOVL aircraft flight demonstrator was studied. The STOVL aircraft uses ejectors powered by engine bypass flow together with vectored core exhaust to achieve vertical thrust capability. Bypass flow and core flow are exhausted through separate nozzles during wingborne flight. Six near term turbofan engines were examined for suitability for this aircraft concept. Fan pressure ratio, thrust split between bypass and core flow, and total thrust level were used to compare engines. One of the six candidate engines was selected for the flight demonstrator configuration. Propulsion related to this aircraft concept was studied. A preliminary candidate for the aircraft reaction control system for hover attitude control was selected. A mathematical model of transfer of bypass thrust from ejectors to aft directed nozzle during the transition to wingborne flight was developed. An equation to predict ejector secondary air flow rate and ram drag is derived. Additional topics discussed include: nozzle area control, ejector to engine inlet reingestion, bypass/core thrust split variation, and gyroscopic behavior during hover.

Beard, B. B.↗
NASA NTRS1983

Upper Atmosphere Research Satellite (UARS) trade analysis

The Upper Atmosphere Research Satellite (UARS) which will collect data pertinent to the Earth's upper atmosphere is described. The collected data will be sent to the central data handling facility (CDHF) via the UARS ground system and the data will be processed and distributed to the remote analysis computer systems (RACS). An overview of the UARS ground system is presented. Three configurations were developed for the CDHF-RACS system. The CDHF configurations are discussed. The IBM CDHF configuration, the UNIVAC CDHF configuration and the vax cluster CDHF configuration are presented. The RACS configurations, the IBM RACS configurations, UNIVAC RACS and VAX RACS are detailed. Due to the large on-line data estimate to approximately 100 GB, a mass storage system is considered essential to the UARS CDHF. Mass storage systems were analyzed and the Braegan ATL, the RCA optical disk, the IBM 3850 and the MASSTOR M860 are discussed. It is determined that the type of mass storage system most suitable to UARS is the automated tape/cartridge device. Two devices of this type, the IBM 3850 and the MASSTOR MSS are analyzed and the applicable tape/cartridge device is incorporated into the three CDHF-RACS configurations.

Fox, M. M.↗