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Results for “SIMULATION METHODS”

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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

FESS Design Simulations: methods, tools, & issues for the edge/scrape-off-layer region

This topic describes the plasma and neutral particles in the transition boundary region between the hot core plasma and the surrounding material walls. A key geometrical transition that occurs in this region is where the equilibrium magnetic field changes topology from a set of closed, nested magnetic flux surfaces inside the magnetic separatrix to flux surfaces, and therefore magnetic field lines that intersect material walls. Because the plasma exhaust heat flows very rapidly along the field lines, these intersection locations can have heat fluxes much higher than the walls can withstand. The most promising strategy pursued here to avoid this problem is injection of moderate-Z impurities that radiate the exhaust power over a much larger surface area on the walls, thus keeping the peak heat flux at or below the goal of 10 MW/m 2 . Further, the intrusion of injected and wall-sputtered impurities into the core region must be kept below certain limits to prevent degradation of the fusion power generated in the core.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1985

A three-dimensional incompressible flow simulation method and its application to the Space Shuttle main engine. II Turbulent flow

An implicit finite difference code cast in general curvilinear coordinates is further developed for three-dimensional incompressible turbulent flows. The code is based on the method of pseudocompressibility and utilizes the Beam and Warming implicit approximate factorization algorithm to achieve computational efficiency. A multiple-zone method is further extended to include composite-grids to overcome the excessive computer memory required for solving turbulent flows in complex three-dimensional geometries. A simple turbulence model is proposed for internal flows. The code is being used for the Space Shuttle Main Engine (SSME) internal flow analyses.

Chang, J. L. C.↗
NASA NTRS1986

Investigation of advanced fault insertion and simulator methods

The cooperative agreement partly supported research leading to the open-literature publication cited. Additional efforts under the agreement included research into fault modeling of semiconductor devices. Results of this research are presented in this report which is summarized in the following paragraphs. As a result of the cited research, it appears that semiconductor failure mechanism data is abundant but of little use in developing pin-level device models. Failure mode data on the other hand does exist but is too sparse to be of any statistical use in developing fault models. What is significant in the failure mode data is that, unlike classical logic, MSI and LSI devices do exhibit more than 'stuck-at' and open/short failure modes. Specifically they are dominated by parametric failures and functional anomalies that can include intermittent faults and multiple-pin failures. The report discusses methods of developing composite pin-level models based on extrapolation of semiconductor device failure mechanisms, failure modes, results of temperature stress testing and functional modeling. Limitations of this model particularly with regard to determination of fault detection coverage and latency time measurement are discussed. Indicated research directions are presented.

Dunn, W. R.↗
NASA NTRS1996

Results of the Calibration of the Delays of Earth Stations for TWSTFT Using the VSL Satellite Simulator Method

Two-way satellite time and frequency transfer (TWSTFT) is the most accurate and precise method of comparing two remote clocks or time scales. The accuracy obtained is dependent on the accuracy of the determination of the non-reciprocal delays of the transmit and the receive paths. When the same transponders in the satellite at the same frequencies are used, then the non-reciprocity in the Earth stations is the limiting factor for absolute time transfer.

deJong, Gerrit↗
DOE OSTI2020

Improving Computational Efficiency of Mechanical Finite Element Method Simulations for PV Modules: Preprint

In this work we have elucidated the trade off between structural mechanics FEM model accuracy and computation time by employing lower fidelity viscoelastic models. Results indicate that computation time can easily be cut in half while only expecting a potential maximum error of 10 % by considering lower fidelity models. A novel approach to produce the Prony Series fit for viscoelastic characterization has also been presented. Employing this approach, we were able to achieve a further 10 % reduction in computation time without further sacrificing simulation accuracy.

41 EE - Solar Energy Technologies Office (EE-4S)↗