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Travis J.R.,Engineering and Scientific Software Inc. | Piccioni Koch D.,Karlsruhe Institute of Technology
International Journal of Hydrogen Energy | Year: 2014

The Computational Fluid Dynamic (CFD) code GASFLOW was used to simulate a Bonfire test for studying the safety performance of high-pressure hydrogen vessels for vehicular storage applications. A thermal loading model representing the azimuthal temperature dependency of the internal gas was implemented in the simulation code GASFLOW and is described in details in this paper. The GASFLOW simulations show good agreement with previous simulation results and with data. © 2014 Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source

Travis J.R.,Engineering and Scientific Software Inc. | Piccioni Koch D.,Karlsruhe Institute of Technology | Breitung W.,Simaps GmbH
International Journal of Hydrogen Energy | Year: 2012

A non-equilibrium two-phase single-component critical (choked) flow model for cryogenic fluids is developed from first principle thermodynamics. Modern equations-of-state (EOS) based upon the Helmholtz free energy concepts are incorporated into the methodology. Extensive validation of the model is provided with the NASA cryogenic data tabulated for hydrogen, methane, nitrogen, and oxygen critical flow experiments performed with four different nozzles. The model is used to develop a hydrogen critical flow map for stagnation states in the liquid and supercritical regions. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights. Source

Xiao J.,Karlsruhe Institute of Technology | Travis J.R.,Engineering and Scientific Software Inc.
Annals of Nuclear Energy | Year: 2013

Uncontrolled hydrogen combustion can occur in the nuclear reactor containment during a severe accident. The energetic hydrogen combustion may threaten the integrity of the containment and lead to radioactive material being released into the environment. In order to mitigate the risk of hydrogen combustion, the first step is to understand how the burnable hydrogen cloud develops in the containment. Turbulence modeling is one of the key elements in simulations of the physical phenomena that occur in containment. However, when a turbulence model is used, the computational time is increased in CFD simulations of large-scale reactor containment primarily due to the additional turbulent transport equations and the small time step controlled by the explicitly-treated turbulent diffusion in GASFLOW code. The purpose of this paper is to investigate how critical turbulence modeling is in the simulation of hydrogen/steam distribution in a large-scale, complex reactor containment. In other words, is it acceptable to neglect the turbulent viscosity in the momentum diffusion term in such a large-scale engineering simulation to save computational time? The effect of turbulence models on the gas distribution in the MISTRA 2009 campaign was investigated using the CFD code, GASFLOW. The calculation results improved locally in the region near the jet source when turbulence models were used. For most of the space in the MISTRA facility, which is located away from the source, it seems that the turbulent diffusion was over-predicted by the turbulence models, and better agreements with the experimental data were obtained by simply using molecular viscosity. These results indicate that with turbulence models, more computational time is required, and the improved calculation results are local and limited. It appears that the predictions are reasonably good when only molecular viscosity is considered in the diffusion terms. Due to the limited computational resources, we must investigate the trade-offs between computational effort and accuracy, particularly in large-scale engineering applications. © 2013 Elsevier Ltd. All rights reserved. Source

Travis J.R.,Engineering and Scientific Software Inc. | Piccioni Koch D.,Karlsruhe Institute of Technology
Journal of Energy Storage | Year: 2015

Cryo-compressed hydrogen vessels for automotive application were simulated by means of the GASFLOW Simulation Code by using real gas equations of state for hydrogen based on Leachman's NIST model and a modified van der Waals Model. The hydrogen tank systems here considered are those based on hydrogen storage concepts developed by the Bayerische Motoren Werke (BMW) Group and produced by the Lawrence Livermore National Laboratory (LLNL) and the Structural Composite Industries (SCI). In order to validate the GASFLOW simulations, the data and the simulation results provided in the frame of the HySIM project were used. The GASFLOW simulations show good agreement with data as well as with the HySIM simulations. The two real gas equations of state, Leachman's NIST and modified van de Waals used in this study produced nearly identical results. © 2015 Elsevier Ltd. Source

Xiao J.,Karlsruhe Institute of Technology | Travis J.R.,Engineering and Scientific Software Inc. | Royl P.,Karlsruhe Institute of Technology | Necker G.,Karlsruhe Institute of Technology | And 2 more authors.
Nuclear Engineering and Design | Year: 2016

GASFLOW is a three dimensional semi-implicit all-speed CFD code which can be used to predict fluid dynamics, chemical kinetics, heat and mass transfer, aerosol transportation and other related phenomena involved in postulated accidents in nuclear reactor containments. The main purpose of the paper is to give a brief review on recent GASFLOW code development, validations and applications in the field of nuclear safety. GASFLOW code has been well validated by international experimental benchmarks, and has been widely applied to hydrogen safety analysis in various types of nuclear power plants in European and Asian countries, which have been summarized in this paper. Furthermore, four benchmark tests of a lid-driven cavity flow, low Mach number jet flow, 1-D shock tube and supersonic flow over a forward-facing step are presented in order to demonstrate the accuracy and wide-ranging capability of ICE'd ALE solution algorithm for all-speed flows. GASFLOW has been successfully parallelized using the paradigms of Message Passing Interface (MPI) and domain decomposition. The parallel version, GASFLOW-MPI, adds great value to large scale containment simulations by enabling high-fidelity models, including more geometric details and more complex physics. It will be helpful for the nuclear safety engineers to better understand the hydrogen safety related physical phenomena during the severe accident, to optimize the design of the hydrogen risk mitigation systems and to fulfill the licensing requirements by the nuclear regulatory authorities. GASFLOW-MPI is targeting a high performance, efficient, robust, well verified and validated all-speed CFD code for safety analysis of nuclear reactor containments and other large scale conventional industrial applications. © 2016 Elsevier B.V. All rights reserved. Source

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