Direct numerical simulations of grain-scale crystal plasticity in engineering components.
Abstract not provided.
Battaile, Corbett Chandler.↗
SEARCH · Search NASA
Results for “Engine Simulation”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Hierarchical Engine for Large-scale Infrastructure Co-Simulation
HELICS is designed to support very-large-scale (100,000+ federates) cosimulations with off-the-shelf power-system, communication, market, and end-use tools. Other key features include cross platform operating system support, the integration of both event driven (e.g., packetized communication) and time-series (e.g., power flow) simulations, and the ability to co-iterate among federates to ensure physical model convergence at each time step.
Source record↗
The Role of Computational Simulation Workflow in Decision Making for High Consequence Engineering Systems.
Abstract not provided.
Orient, George Edgar↗
Multi-dimensional computational combustion of highly dilute, premixed spark-ignited opposed-piston gasoline engine using direct chemistry with a new Primary Reference Fuel mechanism
Explore the source record for details and available documents.
Mittal, Anshul↗
Grizzly Development for Light Water Reactor and Advanced Reactor Applications in Fiscal Year 2021
This report summarizes work performed during Fiscal Year (FY) 2021 at Idaho National Laboratory (INL) for the U.S. Department of Energy’s Nuclear Engineering Advanced Modeling and Simulation (NEAMS) program for the Structural Materials and Chemistry Technical Area in the work package entitled “MS-21IN050106 - Structural Materials - INL.” This effort mainly focused on development and application of capabilities for engineering-scale analysis of nuclear reactor structural components in the Grizzly and BlackBear codes. These efforts include performance improvements and application of models for high-temperature component response, cluster dynamics modeling of precipitation in light water reactor pressure vessel steel, engineering-scale capability development in the areas of concrete simulation and reactor pressure vessel analysis, and preparation for and conducting an independent assessment of the adherence of these codes to software quality standards.
36 MATERIALS SCIENCE↗
Tunable thermal conductivity via domain structure engineering in ferroelectric thin films: A phase-field simulation
Effective thermal conductivity as a function of domain structure is studied by solving the heat conduction equation using a spectral iterative perturbation algorithm in materials with inhomogeneous thermal conductivity distribution. Using this proposed algorithm, the experimentally measured effective thermal conductivities of domain-engineered {001} p- BiFeO 3 thin films are quantitatively reproduced. In conjunction with two other testing examples, this proposed algorithm is proven to be an efficient tool for interpreting the relationship between the effective thermal conductivity and micro-/domain-structures. By combining this algorithm with the phase-field model of ferroelectric thin films, the effective thermal conductivity for PbZr 1-x Ti x O 3 films under different composition, thickness, strain, and working conditions is predicted. It is shown that the chemical composition, misfit strain, film thickness, film orientation, and a Piezoresponse Force Microscopy tip can be used to engineer the domain structures and tune the effective thermal conductivity. Furthermore, we expect our findings will stimulate future theoretical, experimental and engineering efforts on developing devices based on the tunable effective thermal conductivity in ferroelectric nanostructures.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Diagnostics of the Supernova Engine
The standard engine behind core-collapse supernovae is continuously evolving with increasingly detailed models. At this time, most simulations focus on an engine invoking turbulence above the proto-neutron star, sometimes termed the “convection-enhanced” engine. Finally, we review this engine and why it has become the standard for normal supernovae, focusing on a wide set of observations that provide insight into the supernova engine.
79 ASTRONOMY AND ASTROPHYSICS↗
Modeling Radiative Heat Transfer and Turbulence-Radiation Interactions in Engines
Detailed radiation modelling in piston engines has received relatively little attention to date. Recently, it is being revisited in light of current trends towards higher operating pressures and higher levels of exhaust-gas recirculation, both of which enhance molecular gas radiation. Advanced high-efficiency engines also are expected to function closer to the limits of stable operation, where even small perturbations to the energy balance can have a large influence on system behavior. Here several different spectral radiation property models and radiative transfer equation (RTE) solvers have been implemented in an OpenFOAM-based engine CFD code, and simulations have been performed for a full-load (peak pressure ~200 bar) heavy-duty diesel engine. Differences in computed temperature fields, NO and soot levels, and wall heat transfer rates are shown for different combinations of spectral models and RTE solvers. The relative importance of molecular gas radiation versus soot radiation is examined. And the influence of turbulence-radiation interactions is determined by comparing results obtained using local mean values of composition and temperature to compute radiative emission and absorption with those obtained using a particle-based transported probability density function method.
33 ADVANCED PROPULSION SYSTEMS↗
Increasing ROI Using Your Digital Twin for Model Based Engineering
The purpose of this work is to identify innovative ways of using the plant reference simulator or digital twin differently than it has traditionally been used in the past. This paper will identify reasons that the plant reference simulator will support varying levels of model based design and engineering. I will point out real world examples in which the plant reference simulator was used to identify problems with engineering designs, digital control systems and plant modifications. The earlier these issues can be identified and resolved, the less impact they have on the plant modification or upgrade. By using the plant reference simulator earlier in the engineering process, utilities and engineering organizations can minimize costly outage extensions and increase the return on the investment made in the simulator.
42 ENGINEERING↗
Multi-Physics Simulation of The TRIGA Reactor
In nuclear engineering, the description of phenomena occurring in the core involves a coupling between neutronic and thermal hydraulics through the so called reactivity or thermal feedback. In water cooled reactor, thermal feedback and temperature coefficients of reactivity are important, when temperature changes, microscopic cross sections change as well impacting directly the neutron flux and so the thermal power. Other feedback, such as the variation of the macroscopic cross section due to a modification of the density can also have a significant impact on the core performance of the reactor. Those reasons were naturally leading in the development of coupling method in order to predict correctly the behaviour of the core in normal operation and accidental situation. This work describes the coupling scheme developed for the description of the TRIGA mark II reactor at JSI. The demonstration case presented here, the reactor is operating in steady state configuration at several power levels. The aim of our calculation was, for a given thermal power of the reactor, to numerically reproduce fuel temperature value monitored during reactor operation. The expected impact of the control rod on the neutron flux distribution was also verified. The predictions of the coupling scheme seem to be correct according to the few temperature measurements available and the expected neutron flux behaviour expecting from a control rod motion. We are considering precise measurement of the fuel temperature at more positions but also in the coolant channels between the fuel elements to complete the experimental validation phase. An upgrade of the coupling scheme into the transient mode is also considered to observe self-stabilisation of the power level, after a control rod perturbation, due to the negative temperature reactivity coefficient of the fuel. (authors)
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
Model Development and Analysis of Clean and Efficient Engine Combustion FY 2018 Annual Progress Report
Simulations of 1D laminar flames using detailed kinetic mechanisms are useful in a wide variety of engine combustion applications. The most common use is in the computation of laminar flame speeds, which are useful for chemical mechanism validation, as inputs to turbulent flame speed correlations, and to predict knocking in spark-ignition engines. Other applications include generation of flamelet libraries for CFD simulations and prediction of combustion dynamics in micro-flow reactors. These fundamental combustion simulations are an important component in the study of realistic transportation fuel models in boosted spark-ignition and multi-mode engine configurations.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
Evolution at the Edge: Real-Time Evolution for Neuromorphic Engine Control
Neuromorphic computing systems are attractive for real-time control at the edge because of their low power operation, real-time processing capabilities and their potential ability to do online learning. In this work, we describe an approach for performing real-time evolution of spiking neural networks for neuromorphic systems at the edge called Neuromorphic Optimization using Dynamic Evolutionary Systems or NODES. We apply this approach to real-time combustion engine control and develop an engine-specific hardware platform for NODES called FireBox. We demonstrate how the real-time evolution approach works in simulation and the performance of networks trained in simulation on the physical engine.
Maldonado Puente, Bryan [ORNL] (ORCID:000000033880↗
Reduced chemical model for low and high-temperature oxidation of fuel blends relevant to internal combustion engines
A hybrid approach is proposed to develop reduced kinetic models for complex engine-relevant fuels. The reduced mechanism is composed of a core submechanism including C0-C4 chemistry, ethanol chemistry, and NOx chemistry and a fuel-dependent submechanism. The fuel-dependent submechanism consists of three species and ten reactions describing both the low and high-temperature fuel decomposition pathways. Calibrations for these reactions can be made for single component and multicomponent mixtures using experimental targets or results from detailed kinetic mechanisms. In the present study, the methodology is applied to the combustion of gasoline surrogates. Reduced mechanisms are calibrated for primary references fuels and multicomponent mixtures at engine-relevant pressures. The reduced mechanisms capture the low-temperature heat release and negative temperature coefficient (NTC) behavior, which are important to simulations of internal combustion engine performance. The mechanisms are very compact in size and can be easily calibrated for multicomponent mixtures without any detailed knowledge of the chemistry of the fuel components, making them well suited for CFD simulations of new fuel blends.
02 PETROLEUM↗
Numerical study of advanced compression ignition and combustion in a gasoline direct injection engine
Multi-mode combustion strategies may provide a considerable thermal efficiency improvement targeted at part-load operating conditions for light-duty spark-ignition (SI) engines. The extension from boosted SI mode at high loads to advanced compression ignition (ACI) mode at low loads can be achieved by increasing compression ratio and utilizing intake air heating. In order to enable an accurate control of intake charge condition for ACI control and rapid mode-switches, it is essential to gain fundamental insight into the autoignition process with regard to thermal and fuel-air mixture stratification in the combustion chamber. In this work, a computational fluid dynamics (CFD) study is carried out to reveal some degrees of correlation between the mixture and thermal stratifications induced by the cylinder wall temperature and combustion-phasing across varying engine load conditions. The computational analysis begins with a calibrated simulation setup best matching the engine experiments, and subsequently evaluates the baseline setup for an extended range of engine load conditions for two excess-air ratio cases. The present study emphasizes the dominance of thermal stratifications for autoignition process due to wall temperature effects depending on the engine load conditions of interest. In addition, this study also aims to provide insight into the impact of mixture stratification on cyclic variability, especially at colder wall engine conditions (e.g., cold start). Observations herein provide highlight of the propensity of autoignition in correlation with mixture reactivity space.
Advanced Compression Ignition (ACI) engine↗
NEAMS-Multiphysics MOOSE End Year Framework Activities FY20
The Multiphysics Object Oriented Simulation Environment (MOOSE) is a general finite element package meant for high performance solution of multiphysics problems in science and engineering. In this report, we present additions and enhancements to MOOSE funded by the Nuclear Engineering Advanced Modeling and Simulation (NEAMS) program. NEAMS-funded MOOSE framework library improvements include: expansion of support for multi-level multi-application restart; enhancement of coupling between native MOOSE applications and external libraries; addition of a sparse automatic differentiation (AD) container enabling non-local degree of freedom coupling; block-specific quadrature rules; further development of an eigenvalue executioner; faster setup of periodic boundary conditions; and creation of a mesh meta-data system streamlining simulation startup. Besides developing the framework library, NEAMS funds were used to overhaul a swath of important MOOSE infrastructure in order to substantially improve user experience. These critical infrastructure changes included adapting MOOSE to python 3, improving the test harness to catch race conditions, and most importantly transitioning MOOSE to use Conda, a globally known packaging system, that greatly eases software adoption.
97 MATHEMATICS AND COMPUTING↗
Toward connecting core-collapse supernova theory with observations. I. Shock revival in a 15 M {sub ☉} blue supergiant progenitor with SN 1987A energetics
We study the evolution of the collapsing core of a 15 M {sub ☉} blue supergiant supernova progenitor from the core bounce until 1.5 s later. We present a sample of hydrodynamic models parameterized to match the explosion energetics of SN 1987A. We find the spatial model dimensionality to be an important contributing factor in the explosion process. Compared to two-dimensional (2D) simulations, our three-dimensional (3D) models require lower neutrino luminosities to produce equally energetic explosions. We estimate that the convective engine in our models is 4% more efficient in 3D than in 2D. We propose that the greater efficiency of the convective engine found in 3D simulations might be due to the larger surface-to-volume ratio of convective plumes, which aids in distributing energy deposited by neutrinos. We do not find evidence of the standing accretion shock instability or turbulence being a key factor in powering the explosion in our models. Instead, the analysis of the energy transport in the post-shock region reveals characteristics of penetrative convection. The explosion energy decreases dramatically once the resolution is inadequate to capture the morphology of convection on large scales. This shows that the role of dimensionality is secondary to correctly accounting for the basic physics of the explosion. We also analyze information provided by particle tracers embedded in the flow and find that the unbound material has relatively long residency times in 2D models, while in 3D a significant fraction of the explosion energy is carried by particles with relatively short residency times.
79 ASTRONOMY AND ASTROPHYSICS↗
Preliminary Design Studies for a Hydro-Growth Radiography Platform to Study the Double Shell Ablator Joint
Double shell target assembly requires mating two hemispheres of aluminum to form the ablator, and the design of the mating joint governs the dimensions of the gap that remains following ablator assembly. Radiographic data from double shell implosions with two different joint designs demonstrate the importance of having a smaller outer gap to minimize perturbation growth, but higher quality data is desirable for validating simulations of such localized engineering features. A double shell hydrogrowth radiography platform is proposed to enable detailed measurements of the joint feature evolution for comparison to simulation predictions. The conservative design is based on a successfully fielded double shell keyhole target, but the tungsten inner shell is replaced with molybdenum to allow imaging with X-rays from a zirconium backlighter (16.3 keV). Eulerian radiation-hydrodynamics simulations with adaptive mesh refinement are used to predict joint feature evolution for several different joint designs. Synthetic radiographs produced from ablator-only calculations demonstrate that the evolution of different joint morphologies can be radiographed and distinguished. Feedthrough of the joint perturbation to a molybdenum inner shell is predicted to be measurable at a convergence ratio of 2.
36 MATERIALS SCIENCE↗
Advanced Simulation Aided Metallic Fuel Design
Nuclear engineering is reaching a domain space in which computational power and methods are starting to surpass the models that are used to simulate nuclear fuel rods. As these models are updated, simulations utilizing different compositions, operating conditions, fabrication techniques, and geometries can provide core designers with an important first step towards fuel qualification. Due to the cost associated with fuel irradiations, it can be expected that time and money spent building better fuel models may provide an attractive return during initial studies of advanced fuels, especially with regards to fuels beyond the extensively studied uranium oxide system. In general, the primary U.S. experience with irradiated fuel rods beyond traditional oxide fuel is with binary (U-Zr) and ternary (U-Pu-Zr) metal fuels. The bulk of the experimental data for metal fuels is obtained from rods irradiated in the EBR-II sodium fast reactor (SFR), thus many of the correlations developed for metal fuels comes from the post-irradiation (PIE) examination of EBR-II rods. One of the unique characteristics that set U-Pu-Zr fuels apart from traditional oxide fuels is the presence of different phases that develop in the fuel during irradiation. Each of these different phases has unique thermal, mechanical, and diffusive behavior. The transitions between these phases are not static as the initially homogenous zirconium diffuses towards the center and edge of the fuel rod, resulting in a low-Zr, high-U ring. Along with the differing material properties that occur in each phase, the increase in uranium corresponds to an increase in localized fission and power production. The direct coupling between the thermal and diffusion solves highlights one of the many examples of tightly coupled phenomenon that are present in nuclear fuel, and motivation for the development of codes that simultaneously solve each piece of physics in a fully-coupled manner.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗