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At least 271 records · Page 15

All sources NASA NTRS DOE OSTI

DOE OSTI2013

Finite Volume Based Computer Program for Ground Source Heat Pump System

This report is a compilation of the work that has been done on the grant DE-EE0002805 entitled "Finite Volume Based Computer Program for Ground Source Heat Pump Systems." The goal of this project was to develop a detailed computer simulation tool for GSHP (ground source heat pump) heating and cooling systems. Two such tools were developed as part of this DOE (Department of Energy) grant; the first is a two-dimensional computer program called GEO2D and the second is a three-dimensional computer program called GEO3D. Both of these simulation tools provide an extensive array of results to the user. A unique aspect of both these simulation tools is the complete temperature profile information calculated and presented. Complete temperature profiles throughout the ground, casing, tube wall, and fluid are provided as a function of time.

15 GEOTHERMAL ENERGY↗

DOE OSTI2019

Thermal analysis of projected molten salt compositions during FFTF and EBR-II used nuclear fuel processing

This work studies the change in liquidus temperature of the salt used in the Mk-IV electrorefiner at the Idaho National Laboratory during processing campaigns of sodium-bonded driver fuels from Experimental Breeder Reactor II and the Fast Flux Test Facility reactor. Modeling and Simulation Tool for Electrochemical Recycling Systems (MASTERS), an INL proprietary pyroprocessing flowsheet simulation tool, was used to simulate the processing campaigns and determine the resulting composition changes of the Mark-IV electrorefiner salt. Surrogate salt samples simulating the Mk-IV electrorefiner salt during the fuel processing campaigns were prepared, and the thermal properties were measured via differential scanning calorimetry. Results from this study indicate that after processing approximately 2,150 kg of uranium metal from used fuel, the liquidus temperature of the molten salt exceeds 520°C, which is a significant increase from 352°C (the melting temperature of eutectic LiCl-KCl). It was also discovered that the liquidus temperature is strongly dependent on the amount of NaCl accumulating in the Mk-IV electrorefiner salt. Thus, the assessment of the liquidus temperature during the subsequent fuel processing campaigns can be simplified by considering the ternary LiCl-KCl-NaCl system only.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2016

PV Shading Database [SWR-16-36]

The software is a simplified method for modeling the impact of arbitrary partial shading conditions on PV array performance. The software implements a simple method for modeling shade loss: a database of shade impact results (loss percentages), generated using a validated, detailed simulation tool and encompassing a wide variety of shading scenarios. The database is intended to predict shading losses in crystalline silicon PV arrays and is accessed using basic inputs generally available in any PV simulation tool. Performance predictions using the database are within 1-2% of measured data for several partially shaded PV systems, and within 1% of those predicted by the full, detailed simulation tool on an annual basis. The shade loss database shows potential to considerably improve performance prediction for partially shaded PV systems.

Janzou, Steven↗

DOE OSTI2013

Modularity and adaptability

The primary question I am addressing is how to construct simulation tools, in this case pri marily PDE simulations, that can be made to efficiently use a future computer whose construction and parameters are not known exactly, but whose general construction can be inferred from current prevailing hardware trends. These trends inform our best estimates of the likely composition of such a next generation machine, and the outlook is that the computers of the future will be highly het erogenous, will penalize excessive communication (particularly with far away pieces of the machine), can likely be tuned to trade pure speed for reliability, and may experience frequent disruptions. In such an environment, my position as to what mathematical research should be performed to aid in this endeavor can be summed up as a need to stress the following points: • Increased modularity of the simulation tool, • Retention of original problem definition as much as possible, and • Provide and analyze flexible alternatives.

97 MATHEMATICS AND COMPUTING↗

NASA NTRS1979

The ground processing simulator - A tool for mission model analysis and planning from a launch site perspective

The Ground Processing Simulator (GPS) is a computer-assisted planning tool designed and developed for Space Shuttle launch site application. Utilizing two programming languages, General Purpose Simulation System and FORTRAN, GPS provides the capability to analyze proposed Shuttle mission models via computer simulation. NASA-developed mission models which specify Shuttle launch rates, mission durations, cargo elements, and designated launch site are tested for feasibility by the simulator. GPS produces facility utilization schedules (including the identification of conflicts), launch data options, cargo element requirement dates, ground support equipment inventory requirements, and other data necessary to assess both the programmatic and launch site resources required to support proposed mission models. The purpose of this computer-assisted analysis is to determine methods which will permit the launching of the maximum number of cargoes per year on schedule, and in the sequence desired, with the minimum expenditure of resources.

Ralph, J. A.↗

NASA NTRSDate not supplied

Advancing xEMU Lunar Dust Mitigation Devices

Fine, electrically charged, glass like dust particles caused significant damage to the Apollo EMU9 during lunar EVAs, identified as one of the greatest challenges to future exploration. Passive Lunar Dust Mitigation Devices (LDMD) were developed, within a SBIR Phase II, to prohibit this dust from interrupting venting space suit component operation. A Computational Fluid-Dynamics and Discrete Element Method (CFD-DEM) Simulation Tool was developed at the University of Colorado, Boulder to predict venting gas flow ability to self-clean adhered dust particles from LDMD surfaces. Lunar dust properties (i.e., adhesion and cohesion strengths) required to complete Simulation Tool analysis are relatively unknown due to considerable differences between the Earth and the Moon (i.e., gravity, humidity) and due to an absence of dust particles in their native state. Analytically determining gas flow velocity, density and direction within the fluid Boundary Layer, microns from LDMD surfaces presented a second challenge. Dusty Plasma Chamber testing is being performed at Auburn University, Auburn to observe electrostatically charged dust behavior as it adheres to LDMD prototypes and specific geometry and is then blown away by metered gas flow. Test articles were developed to offer insight into the impact of different flow geometries, surface roughness and dust removal within the gas Boundary-Layer. Observed dust behavior is currently being developed to support the CFD-DEM analysis. Many Simulation Tool analytical cases have been processed to support the intention of completing sensitivity studies to assess how different dust adherence values and Boundary Layer fluid properties impact LDMD self-cleaning effectivity.

Thomas J Stapleton↗

DOE OSTI2025

Intelligently Partitioned Phasor-EMT Hybrid Simulations of Large-Scale, High-IBR Power Systems

As the penetration level of power electronics-interfaced renewables such as photovoltaics (PV) and wind has surged in modern electric grids, new operational risks caused by the dynamics of those inverter-based resources (IBRs) are emerging in parallel. Lessons learned from various grid events include that the impact of IBRs on system-level grid stability will become prominent along with the increase of renewables and that the short-timescale dynamic impacts of IBRs on grid stability are not fully captured by current commercial dynamic simulation tools [1] [2]. For example, IBRs can be controlled to mitigate those destabilizing interactions, but conventional phasor-domain tools (e.g. PSS/E, PSLF) often cannot capture that; likewise, the existing electromagnetic transient (EMT) simulation tools (e.g. PSCAD, EMTP) can simulate detailed IBR controls, but for large power systems with many IBRs, slow simulation speeds severely impede the ability to study dynamic events [3] [4]. Massively paralleling simulations using high-performance computing (HPC) can help address this, especially now that cloud-based HPC capability is widely available, but today s EMT tools are not HPC-compatible, and parallelization of dynamic simulation solvers is not trivial because each region can dynamically affect the others. Thus, dynamic simulation of grids with very large numbers of IBRs potentially poses a barrier to the ongoing energy transition.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2015

Interoperability format translation and transformation between IFC architectural design file and simulation file formats

Automatically translating a building architecture file format (Industry Foundation Class) to a simulation file, in one aspect, may extract data and metadata used by a target simulation tool from a building architecture file. Interoperability data objects may be created and the extracted data is stored in the interoperability data objects. A model translation procedure may be prepared to identify a mapping from a Model View Definition to a translation and transformation function. The extracted data may be transformed using the data stored in the interoperability data objects, an input Model View Definition template, and the translation and transformation function to convert the extracted data to correct geometric values needed for a target simulation file format used by the target simulation tool. The simulation file in the target simulation file format may be generated.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗

DOE OSTI2015

Interoperability format translation and transformation between IFC architectural design file and simulation file formats

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2023

ARES v1.x - Performance Portable Tool to Simulate Supernovae based on Parthenon Framework

Historically, codes for simulating supernovae (such as Arepo, FLASH or LEAFS) have been at the forefront of scientific high-performance computing to the immense computational resources required for full 3D simulations. However, given the shift towards heterogenous HPC architectures, many current-generation codes are at the risk of losing their competitiveness as they are only designed to run on homogeneous CPU-only systems. There exist several efforts to enable these codes for GPU’s, however, these efforts only consider specific architectures or vendors (e.g., implement only CUDA or HIP), limiting themselves to a small range of exascale computing systems. Frameworks such as Kokkos aim to provide a framework which is agnostic of the targeted architecture, enabling the development of performant and portable code. In the Ares code, we develop a performance portable tool to simulate supernovae based on the Parthenon Framework, which in turn uses Kokkos in the background. Here, the Parthenon Framework provides an interface to the underlying mesh-refinement routines, which form the backbone of our code. In addition, we incorporate the already existing Singularity-EOS toolkit to provide us with various equations of state, primarily the Helmholtz equation of state. We also include the JINA Reaclib as a basis for our nuclear network solver. Finally, we implement a gravity solver to complete the required physics. This setup will provide us with a minimal code base to simulate supernova in a similar style to the tried-and-tested Arepo code, but in a futureproof performance portable framework.

Lim, Hyun↗

DOE OSTI2020

An Adaptive-Mesh-Refinement Based Computational Tool for Simulating Catalysis at Mesoscale

In this work, we present a computational tool for mesoscale applications using open-source exascale- computing compatible adaptive-mesh-refinement (AMR) library, AMReX [2]. AMReX is software library that enables development of application solvers with block-structured Cartesian AMR. Our tool has capabilities to include realistic geometry representation, chemical species transport, reactions and thermodynamics that are critical for capturing mesoscale physics. A significant achievement is the ability of our solver to automatically import electron microscopy data in the form of a stereolithography (STL) or pixelated file format (mrc, tiff) without undergoing the tedious task of unstructured mesh generation. This feature allows for rapid simulation of catalyst particles with complex morphologies using an immersed-boundary formulation. The use of AMR allows for higher resolutions at catalyst surface interfaces, which in turn provides an accurate description of surface reactions and transport. Our solver uses a hybrid distributed and shared memory parallelism (OpenMP/GPU-based) with which strong scaling up to 10,000 processors for realistic catalyst particle simulations have been demonstrated.

BIOMASS FUELS,MATHEMATICS AND COMPUTING↗

NASA NTRSDate not supplied

Autogenous Pressurization of a Cryogenic Tank Using Computational Fluid Dynamics

Well-validated simulation tools can be used to predict long-term storage and transfer of cryogenic propellants, which are essential to NASA’s mission plan to return to the Moon and continue to Mars. Autogenous pressurization of propellant tanks is used to supply rocket engine turbopumps with pressurized liquid fuel and oxidizer, preventing cavitation. Additionally, autogenous pressurization can be used to pressurize propellant tanks to support on-orbit propellant transfer. In lieu of expensive tests conducted on-orbit, accurate predictive computational models of these processes can be used to reduce system and propellant mass as well as mission risk. Using simulation tools also reduces the cost of analyzing and developing this technology. This study presents a multiphase computational fluid dynamics model capable of simulating autogenous pressurization of a large cryogenic tank using the commercial code STAR-CCM+. Experimental data from a full-scale tank pressurization test under terrestrial gravity is compared to simulation results using transient error metrics. Comparisons show good agreement and give confidence in using these and other validated simulation tools to develop cryogenic pressurization systems.

Cryogenics↗

NASA NTRSDate not supplied

Autogenous Pressurization of a Cryogenic Tank using Computational Fluid Dynamics

cryogenics↗

DOE OSTI2019

Online simulation powered learning modules for materials science

Simulation tools are playing a significant role in materials science and engineering and beyond their well established importance in research and development, these tools have a vital pedagogical potential. We describe a set of online simulation tools and learning modules designed to help students explore important concepts in materials science where hands-on activities with high-fidelity simulations can provide insight not easily acquired otherwise. The online tools, which involve density functional theory and molecular dynamics simulations, have been designed with non-expert end-users in mind and only a few clicks are required to perform most simulations, yet they are powered by research-grade codes and expert users can access advanced options. All tools and modules are available for online simulation in nanoHUB.org and access is open and free of charge. Importantly, instructors and students do not need to download or install any software. The learning modules cover a range of topics from electronic structure of crystals and doping, plastic deformation in metals, and physical properties of polymers. These modules have been utilized in several core undergraduate courses at Purdue’s School of Materials Engineering, they are self contained, and are easy to incorporate into existing classes.

36 MATERIALS SCIENCE↗

DOE OSTI2016

Heavy-Duty Vehicle Port Drayage Drive Cycle Characterization and Development

In an effort to better understand the operational requirements of port drayage vehicles and their potential for adoption of advanced technologies, National Renewable Energy Laboratory (NREL) researchers collected over 36,000 miles of in-use duty cycle data from 30 Class 8 drayage trucks operating at the Port of Long Beach and Port of Los Angeles in Southern California. These data include 1-Hz global positioning system location and SAE J1939 high-speed controller area network information. Researchers processed the data through NREL's Drive-Cycle Rapid Investigation, Visualization, and Evaluation tool to examine vehicle kinematic and dynamic patterns across the spectrum of operations. Using the k-medoids clustering method, a repeatable and quantitative process for multi-mode drive cycle segmentation, the analysis led to the creation of multiple drive cycles representing four distinct modes of operation that can be used independently or in combination. These drive cycles are statistically representative of real-world operation of port drayage vehicles. When combined with modeling and simulation tools, these representative test cycles allow advanced vehicle or systems developers to efficiently and accurately evaluate vehicle technology performance requirements to reduce cost and development time while ultimately leading to the commercialization of advanced technologies that meet the performance requirements of the port drayage vocation. The drive cycles, which are suitable for chassis dynamometer testing, were compared to several existing test cycles. This paper presents the clustering methodology, accompanying results of the port drayage duty cycle analysis and custom drive cycle creation.

33 ADVANCED PROPULSION SYSTEMS↗

DOE OSTI2017

Software Comparison for Renewable Energy Deployment in a Distribution Network

The main objective of this report is to evaluate different software options for performing robust distributed generation (DG) power system modeling. The features and capabilities of four simulation tools, OpenDSS, GridLAB-D, CYMDIST, and PowerWorld Simulator, are compared to analyze their effectiveness in analyzing distribution networks with DG. OpenDSS and GridLAB-D, two open source software, have the capability to simulate networks with fluctuating data values. These packages allow the running of a simulation each time instant by iterating only the main script file. CYMDIST, a commercial software, allows for time-series simulation to study variations on network controls. PowerWorld Simulator, another commercial tool, has a batch mode simulation function through the 'Time Step Simulation' tool, which obtains solutions for a list of specified time points. PowerWorld Simulator is intended for analysis of transmission-level systems, while the other three are designed for distribution systems. CYMDIST and PowerWorld Simulator feature easy-to-use graphical user interfaces (GUIs). OpenDSS and GridLAB-D, on the other hand, are based on command-line programs, which increase the time necessary to become familiar with the software packages.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2020

Construction of a Code Verification Matrix for Heat Conduction With Finite Element Code Applications

When establishing the pedigree of a simulation tool, code verification is used to ensure that the implemented numerical algorithm is a faithful representation of its underlying mathematical model. During this process, numerical results on various meshes are systematically compared to a reference analytic solution. The selection of analytic solutions can be a laborious process, as it is difficult to establish adequate code confidence without performing redundant work. In this report we address this issue by applying a physics-based process that establishes a set of reference problems. In this process, code simulation options are categorized and systematically tested, which ensures that gaps in testing are easily identified and addressed. The resulting problems are primarily intended for code verification analysis but may also be useful for comparison to other simulation codes, troubleshooting activities, or training exercises. The process is used to select fifteen code verification problems relevant for the one-dimensional steady-state heat conduction equation. These problems are applicable to a wide variety of simulation tools, but, in this work, a demonstration is performed using the finite element-based nuclear fuel performance code BISON. Convergence to the analytic solution at the theoretical rate is quantified for a selection of the problems, which establishes a baseline pedigree for the code. Not only can this standard set of conduction solutions be used for verification of other codes, but also the physics-based process for selecting problems can be utilized to quantify and expand testing for any simulation tool.

42 ENGINEERING↗

NASA NTRSDate not supplied

Pterodactyl: 6-DOF Integration of Guidance and Control Algorithms in Genesis

The NASA-funded Pterodactyl project seeks to advance the current state-of-the-art for entry vehicles by developing novel guidance and control technologies for Deployable Entry Vehicles. This paper builds upon the Pterodactyl architecture that employed eight individually articulating flaps with two options for guidance, bank angle modulation with the Fully Numerical Predictor Corrector Entry Guidance (FNPEG) technique and angle of attack and sideslip modulation with FNPEG uncoupled range control. These, with a linear quadratic regulator controller, have previously been presented in separate 3-DOF trajectory simulations, one for translational motion and another for rotational dynamics. This work will show results for integrated 6-DOF simulations, leveraging recent advancements in trajectory simulation tools, namely the Julia-based Genesis flight simulation tool. Results show similar performance for both schemes when compared to the previously presented 3-DOF results once the controllers were adequately tuned. Angle of attack and sideslip angle modulation necessitated a controller designed at high dynamic pressure conditions, and bank angle modulation necessitated a controller designed at lower dynamic pressure conditions. Notably, the angle of attack and sideslip modulation approach could not achieve the parachute deploy point target Mach number of 2, when only tuning the controller gains, so future work will be needed to improve guidance and control tracking.

EDL↗