Computational Fluid Dynamics Analysis and Structural Safety Assessment of a Mitigation Device to Minimize Consequence of a Containment Bypass Nuclear Accident

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Wung Jae Wang ◽  
Man-Sung Yim
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Safety Assessment ◽  
Equivalent Stress ◽  
Simulation Software ◽  
Inlet Pressure ◽  
Structural Safety ◽  
Cfd Analysis ◽  
Safety Margins ◽  
Computational Fluid Dynamics Analysis

Abstract The thermally induced steam generator tube rupture (TI-SGTR) accident is a principal contributor to mean early and latent cancer fatality among the containment bypass accidents. To mitigate the consequence of a TI-SGTR accident, use of a bypass mitigation device has been proposed. This study investigated the feasibility of using the proposed bypass mitigation device based on computational fluid dynamics (CFD) analysis and structural safety assessment using a commercial simulation software (Fluent). As TI-SGTR accident may occur if main steam safety valve (MSSV) for preventing over pressurization is stuck-open in station black out (SBO) scenario, the analysis included the modeling of the flow of dry steam from MSSV to the capturing pipe of the mitigation system. According to CFD analysis results, after passing MSSV, the inlet pressure was decreased to the atmospheric pressure. The structural safety analysis was based on evaluating the equivalent stress distribution of the capturing pipe. Under three inlet pressure conditions, the largest concentrated stress on the capturing pipe was found to be less than 10% to tensile strength of the steel. For the concrete support, the safety margins may not be sufficient for 8.7 MPa inlet pressure condition. The thermal-mechanical analysis was performed for the period of 15 min, indicating that the effect of thermal expansion is small and that the resulting strain does not pose a concern. The results of this study can also be utilized to study externally released flow through MSSV or to identify directions for supplementing or reinforcing the migration system.

CFD Analysis and Structural Safety Assessment of a Bypass Mitigation Device Used During a Ti-SGTR Accidental Release From a MSSV

2019 ◽  
Author(s):  
Wung Jae Wang ◽  
Man Sung Yim
Keyword(s):  
Safety Assessment ◽  
Power Plants ◽  
Safety Valve ◽  
Electrical Power ◽  
Simulation Software ◽  
Radioactive Material ◽  
Structural Safety ◽  
Fluid Temperature ◽  
Cfd Analysis ◽  
Temperature And Pressure

Abstract In Nuclear power plants, Main steam safety valve (MSSV) is a barrier to prevent overpressure of steam flow by opening the secondary cycle to the atmosphere. Since MSSVs operate at condition of high temperature and pressure, they have possibility for stuck-open failure. If this accident occurs, large amount of steam or gases release through failed MSSV. It may lead Thermally-induced Steam generator tube rupture (TI-SGTR) due to sudden high gradient of temperature and pressure. With loss of electrical power, TI-SGTR occurs, Core will start to melt in 2–3hours after loss of electrical power. When TI-SGTR occurs with core melt, Leakage of radioactive material occurs through MSSV to environment. Though the probability of an accident is very low, the release of radioactive material can lead large cancer risk to the public. Therefore, many studies to mitigate the radioactive materials are in progress such as diversion to containment building or capturing with external mitigation system. In this study, we are focusing on this capturing device. The objective of this study is to analyze integrity of mitigation device using fluid behavior from MSSV to capturing pipe. Hydraulic conditions at safety valve inlet were used from previous researches. Using commercial simulation software, computational fluid dynamics (CFD) analysis was performed for distribution of fluid temperature, pressure, velocity in MSSV and pipes. For structural safety assessment, 1-way Fluid-Structure interaction (FSI) method was used. CFD result was applied for load on structure surfaces to simulate transient structural analysis of mitigation device. As a result, stresses, strains of capturing pipe were calculated and integrity was discussed.

scholarly journals Aerodynamic Analysis of Spoiler at Varying Speeds and Angles

2021 ◽  
Vol 9 (11) ◽  
pp. 526-535
Author(s):  
Manas Metar
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Analysis ◽  
Wake Region ◽  
Aerodynamic Analysis ◽  
Pressure Drag ◽  
High Speeds ◽  
Computational Fluid Dynamics Analysis ◽  
Computational Fluid Dynamics Cfd ◽  
Simulation Results

Abstract: Spoilers have been there in practice since years for the purpose of improving aerodynamics of a car. The pressure drag created at the end of the vehicle, referred to as wake region affects handling of the vehicle. This could be hazardous for the cars at high speeds. By adding a spoiler to the rear of the car reduces that pressure drag and the enhanced downforce helps in better traction. The paper presents aerodynamic analysis of a spoiler through Computational Fluid Dynamics analysis. The spoiler is designed using Onshape software and analyzed through SIMSCALE software. The simulation is carried out by changing angles of attack and velocities. The simulation results of downforce and drag are compared on the basis of analytical method. Keywords: Designing a spoiler, Design and analysis of spoiler, Aerodynamics of spoiler, Aerodynamic analysis of spoiler, Computational fluid dynamics, CFD analysis, CFD analysis of spoiler, Spoiler at variable angles, Types of spoilers, Analytical aerodynamic analysis.

Evaluation of Jet Impact Region and Fluid Force Generated From Ruptured Pipes: 2 — Evaluation of Fluid Force Using Computational Fluid Dynamics Analysis

2016 ◽  
Author(s):  
Shiro Takahashi ◽  
Qiang Xu ◽  
Noriyuki Takamura ◽  
Ryo Morita ◽  
Yuta Uchiyama ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Nuclear Power ◽  
Power Plants ◽  
Jet Impingement ◽  
Cfd Analysis ◽  
Fluid Force ◽  
Free Jet ◽  
Jet Impact ◽  
Computational Fluid Dynamics Analysis

Nuclear power plants are designed to avoid damage to their safety installations because of jet impingement when a pipe is ruptured. We have investigated evaluation methods for the design basis of protection of plants against effects of postulated pipe rupture using computational fluid dynamics (CFD) analysis. The steam jet tests obtained using particle image velocimetry (PIV) were conducted in order to verify the CFD analysis. Spread of steam jets could be visualized and the shapes of the steam jets obtained by analysis were almost the same as those by tests. The spread angle of free jet was investigated using CFD analysis. We also measured jet fluid force when a cylindrical structure was installed downstream from the jet nozzle. Steam jet fluid force obtained by analysis was almost the same as that by tests. We judged the CFD analysis to be applicable to evaluation of jet fluid force generated from ruptured pipes.

Characteristic Study of Bi-Cone Solid-Liquid Separation Hydrocyclones Based on Computational Fluid Dynamics Analysis

2007 ◽  
Author(s):  
Lixin Zhao ◽  
Baojun Zhu ◽  
Yanqing Hu ◽  
Zhanzhao Ma
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Short Circuit ◽  
Tangential Velocity ◽  
Cfd Analysis ◽  
Liquid Separation ◽  
Distribution Rule ◽  
Computational Fluid Dynamics Analysis ◽  
Solid Liquid ◽  
Solid Liquid Separation

Numerical simulation of the bi-cone solid-liquid separation hydrocyclones based on Reynolds Stress Model (RSM) is carried out by Computational Fluid Dynamics (CFD) analysis. Re-circulation flow and short-circuit flow phenomena are indicated by simulating results, and distribution rule of axial velocity, radial velocity and tangential velocity of the flow field inside hydrocyclone are obtained. Some of the simulation results are qualitatively in accordance with the Laser Doppler Anemometer (LDA) measuring data, which proves the correctness of turbulence model and computational method. Moreover, the wall erosion problem of the hydrocyclones is also studied. The positions of erosion, which include tangential inlets, boundary of cylinder and large cone section, and the boundary of large cone section and fine cone section, are analyzed and recognized, based on Discrete Phase Model (DPM). Erosion of the revised hydrocyclone is obviously improved and the separation efficiency is enhanced by CFD analysis. At the same time, characteristic of pressure was analyzed.

Computational Fluid Dynamics Analysis for Process Impact Assessment during Thermal Pasteurization of Intact Eggs

2005 ◽  
Vol 68 (2) ◽  
pp. 366-374 ◽  
Author(s):  
SIEGFRIED DENYS ◽  
JAN G. PIETERS ◽  
KOEN DEWETTINCK
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Inactivation Kinetics ◽  
Transient Temperature ◽  
Process Conditions ◽  
Conductive Heat ◽  
Cfd Analysis ◽  
Computational Fluid Dynamics Analysis ◽  
Thermal Pasteurization

Transient temperature and albumen velocity profiles during thermal pasteurization of intact eggs were studied using a commercial computational fluid dynamics (CFD) package. Simulated temperature profiles were in close agreement with experimental data for eggs of different sizes. Convective heat transfer only occurred in the egg white fraction, and conductive heat transfer only occurred in the yolk. For process assessment, a generally accepted kinetic inactivation model for Salmonella Enteritidis was incorporated into the CFD analysis. Minimum process times and temperatures needed to provide equivalent pasteurization at 5-log reductions of the target microorganism were obtained on a theoretical basis. The combination of CFD analysis and inactivation kinetics can be very useful for assessing pasteurization of intact eggs and can enable processors to gain a better understanding of these processes and to establish process conditions for consumer-safe eggs.

Computational Fluid Dynamics Analysis of a Machine Hammer Peened Surface Structure for Lubricated Sliding Contacts

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
D. Trauth ◽  
F. Klocke ◽  
M. Terhorst ◽  
P. Mattfeld
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Bearing Capacity ◽  
Fluid Pressure ◽  
Surface Finishing ◽  
Cfd Analysis ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Surface Textures ◽  
Computational Fluid Dynamics Analysis

Machine hammer peening (MHP) is an incremental surface finishing process. It enables both surface smoothing and texturing. Compared to well-established surface texturing processes, MHP has the advantage of simultaneous induction of strain hardening and compressive residual stresses. Both texturing and surface layer modification are very beneficial in case of mixed-boundary lubrication. MHP has been only recently developed. Therefore, the influence of surface textures manufactured by MHP on tribological interactions is unknown and lacks fundamental investigations. In this work, hydrodynamics of MHP textures is investigated by means of a three-dimensional (3D) computational fluid dynamics (CFD) analysis. The analyzed MHP textures have already been experimentally used to reduce friction in strip drawing tests. Using CFD analysis, an optimal arrangement of multiple elliptically shaped surface structures for maximizing the fluid pressure and the load-bearing capacity is determined. Furthermore, a correlation between the determined process parameters and the lubrication properties is presented. Because of significantly high hydrostatic pressures, cavitation is neglected in this work. Additionally, the effect of structure pileups is neglected in this study. Within the range of parameters investigated, it was found that an arrangement of surface textures by MHP should be transversally overlapping and clearly separated longitudinally. High structure depths, lubricant viscosities, and sliding velocities further improve the load-bearing capacity as well as small fluid-film thicknesses.

scholarly journals Computational fluid dynamics analysis in the ductless whole-house air conditioning system

2020 ◽  
Vol 172 ◽  
pp. 03008
Author(s):  
Rie Tasaka ◽  
Sayaka Kindaichi ◽  
Daisaku Nishina ◽  
Mitsuhiko Maeoki
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Heat Load ◽  
Air Conditioning ◽  
High Energy ◽  
Space Heating ◽  
Cfd Analysis ◽  
Air Conditioner ◽  
Air Conditioning System ◽  
Computational Fluid Dynamics Analysis

Recently, the heat load for space heating in residential houses has been reduced as airtightness, and thermal insulation performance has been improving even in moderate climate regions of Japan. In such situations, the heat load can be handled by one room air-conditioner with high energy efficiency. We report the results of computational fluid dynamics (CFD) analysis of an indoor thermal environment and the airflow distribution during the space heating operation in a ductless house air conditioning system, in which heated air from a room air conditioner installed in a thermal-insulated basement space is distributed throughout the building using air inlets on the floor in each story and open-door rooms without ductworks. To determine the adequate size and position of the air inlets on the floor in this heating system, we evaluated the air circulation performance for changes in the conditions of the air inlets by CFD analysis for a standard two-storey house model in Japan. The results suggest that the air temperature distribution is markedly different in the size and position of the air inlets on the floor. Large volumes of airflow through the openings in the building resulted in maintaining the rooms at a temperature range of 17 to 24 degrees uniformly. These results also provide information for system and building designs for effective space heating and for proper usage when choosing to open or close air inlets in the operational phase.

Study on Manufacturing Tolerances for the Laminar Airfoil

2015 ◽  
Author(s):  
Jaehun Lee ◽  
Kyoung Jin Jung
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Transition Model ◽  
Dynamics Analysis ◽  
Cfd Analysis ◽  
Computational Fluid Dynamics Analysis ◽  
Manufacturing Tolerances ◽  
Forward Facing Step ◽  
Good Agreement

The procedure to determine manufacturing tolerances for the laminar airfoil is explained using the CFD (computational fluid dynamics) analysis. This procedure is applied to a laminar airfoil for the tolerance of the forward-facing step and rearward-facing step. In the CFD analysis the Langtry-Menter SST Transition model is used to simulate a natural transition over the laminar airfoil. The computed tolerances showed good agreement with experimental data.

scholarly journals Computational fluid dynamics analysis for improving temperature distribution in a chili dryer

2018 ◽  
Vol 22 (6 Part A) ◽  
pp. 2615-2623 ◽  
Author(s):  
Escobedo Carrera ◽  
Rivera Ortiz ◽  
Valdivia Guzman ◽  
Ruiz Garcia ◽  
Orenday Desiga
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Temperature Distribution ◽  
Dynamics Analysis ◽  
Cfd Analysis ◽  
Efficient Design ◽  
Computational Fluid Dynamics Analysis ◽  
Specific Geometry ◽  
Numerical Tool ◽  
Energy Equations

Computational fluid dynamics is a numerical tool that is highly accurate to simulate a very large number of applications and processes. The CFD analysis has emerged as a viable technique to provide effective and efficient design solutions. In this paper, a CFD analysis for improving temperature distribution in a chili dryer is presented. The CFD technique is used to simulate the temperature distribution inside the chamber. For this purpose, the continuity, momentum and energy equations are considered. The results obtained by CFD analysis based on a specific geometry are presented in order to improve the temperature distribution. In addition, these results were verified experimentally. The distribution of temperatures showed small differences around 4 K during the warming up period. The simulation and experimental results can be useful for further designs of chili dryers with different specific geometries.

Computational fluid dynamics analysis in microbial fuel cells with different anode configurations

2014 ◽  
Vol 69 (7) ◽  
pp. 1447-1452 ◽  
Author(s):  
Jiyeon Kim ◽  
Hongsuck Kim ◽  
Byunggoon Kim ◽  
Jaecheul Yu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Microbial Fuel Cells ◽  
Electrochemical Reaction ◽  
System Optimization ◽  
Cfd Analysis ◽  
Internal Structures ◽  
Study Results ◽  
Computational Fluid Dynamics Analysis ◽  
Wide Range

A key criterion in microbial fuel cell (MFC) design is that the bio-electrochemical reaction between bacteria and the bulk solution should occur evenly on the electrode surface in order to improve electricity generation. However, experimental optimization of MFC design over a wide range of conditions is limited. Computational fluid dynamics (CFD) technology makes it possible to evaluate physicochemical phenomena such as fluid flows, mass transfer and chemical reaction, which can assist in system optimization. Twelve MFCs (M1–M12) with different internal structures were subjected to CFD analysis. The dead (DS) and working spaces (WS) of the anode compartment were calculated. The flow patterns of the anodic fluid varied according to the internal structures. The WS where the bio-electrochemical reaction can actually occur varied over the range of 0.14–0.57 m2. Based on the above results, the power densities were estimated under the assumption that a monolayer biofilm was formed on the electrode. M11, with 18 rectangular-type internal structures, showed the largest WS of 0.57 m2 and a theoretical maximum power density of 0.54 W/m2. Although the optimization of the MFC configuration with only CFD analysis remains limited, the present study results are expected to provide fundamental data for MFC optimization.

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