scholarly journals CFD simulation of DC-discharge in airflow

2021 ◽  
Vol 2100 (1) ◽  
pp. 012015
Author(s):  
D A Tarasov ◽  
A A Firsov
Keyword(s):  
Atmospheric Pressure ◽  
Discharge Channel ◽  
Cfd Simulation ◽  
Fluid Model ◽  
Three Dimensional ◽  
Flow Discharge ◽  
The Core ◽  
Initial Discharge ◽  
Dc Discharge ◽  
Partial Channel

Abstract The main purpose of this work is to simulate a dynamics of DC discharge in a subsonic airflow. The calculations were performed in the FlowVision 3.12.01 software package. The single-fluid model (MHD approach) of equilibrium plasma was used while the initial discharge channel was set manually. Cylindrical coaxially arranged electrodes were located in the central part of the calculation area, in the core of the airflow. A 5A DC discharge at atmospheric pressure was considered, as well as a simple model of a re-breakdown between parts of discharge filament. In this work, three-dimensional distributions of temperature and current density were obtained during an evolution of discharge in a flow. Discharge channel extension by the airflow and partial channel decay after the re-breakdown process were shown.

Numerical Simulation of Three Dimensional Internal Flow of a PWR Reactor

2016 ◽  
Author(s):  
Jian Ge ◽  
Wenxi Tian ◽  
Tingting Xu ◽  
Jiesheng Min ◽  
Guofei Chen ◽  
...  
Keyword(s):  
Cfd Simulation ◽  
Physical Phenomenon ◽  
Three Dimensional ◽  
Great Influence ◽  
Flow Distribution ◽  
Internal Flow ◽  
Hydraulic Characteristics ◽  
Main Research ◽  
The Core ◽  
Internal Structures

The coolant flow in the reactor pressure vessel (RPV) lower plenum is complex due to the presence of various internal structures, which has a great influence on the flow distribution at the core inlet. In order to study the thermal hydraulic characteristics in the RPV lower plenum, many scaled down test facilities have been built for different PWR reactors such as Juliette, ACOP, and ROCOM. Although the experimental study is still a main research method, it may be not economical in some situations due to the high cost and the long study period. Compared with the experimental method, Computational Fluid Dynamics (CFD) methodology can simulate three dimensional fluid flow in complex geometries and perform parametric studies more easily. The detailed and localized thermal hydraulic characteristics which are difficult to measure during experiments can be obtained. So CFD simulation has been widely used nowadays. One of the purposes of numerical simulations of the internal flow in a RPV is to get the flow distribution at the core inlet, then to make an optimization for the flow diffusor in the RPV lower plenum to improve the core inlet flow distribution homogeneity. Appropriate optimizations for the flow diffusor depends on fully understanding the flow phenomena in the RPV lower plenum. In this paper, Phenomenon Identification and Ranking Table (PIRT) is adopted to analyze the physical phenomenon that occurs in the RPV lower plenum with the typical 900MW reactor internal structures, and the importance of the various physical phenomena and the reference parameters are ranked through expert opinions and literature review. Then a preliminary three dimensional CFD simulation for the reactor vessel is conducted. The main phenomena identified by the PIRT can be observed from the simulation results.

CFD Simulation of Catalytic Oxidation of Ethyl Acetate over Cr-HZSM-5 Catalyst

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Aligholi Niaei ◽  
Darioush Salari ◽  
Seyed Ali Hosseini ◽  
Reza Nabavi ◽  
Azadeh Jodaei
Keyword(s):  
Ethyl Acetate ◽  
Catalytic Oxidation ◽  
Atmospheric Pressure ◽  
Cfd Simulation ◽  
Heterogeneous Reaction ◽  
Three Dimensional ◽  
Particle Diameter ◽  
Complex Catalyst ◽  
Region Temperature ◽  
Different Temperatures

This paper reports the results of a study on a three-dimensional computational fluid dynamics (CFD) simulation for a study of gas catalytic oxidation of ethyl acetate over Cr-HZSM-5 catalyst. A gaseous stream, containing N2, O2 and ethyl acetate (in which ethyl acetate concentration in mixture was 2000 ppmV) with GHSV= 32000 h-1 as the feed, was inserted into a glass reactor, charged with a required amount of Cr-HZSM-5 catalyst under atmospheric pressure. The catalytic reactions were allowed to occur at atmospheric pressure and at different temperatures. Fluent 6.2 was used for the simulation of the catalytic process. The simulation was present for the model geometry of 20 solid spheres in a tube with a tube-to-particle diameter ratio equal to 2. Results of the simulation showed a good agreement with the experimental results. It was experimentally, and by simulation, observed that the increasing of the temperature and the decreasing of the inlet mass flow rate led to the increase of ethyl acetate conversion. Velocity vector profiles of the fluid were obtained with an emphasis on the catalytic region. Temperature and pressure contours of the fluid inside the reactor were predicted by simulation. Furthermore, the surface deposition rate of oxygen (during the step of catalyst oxidation) and species concentration along the reactor were obtained. This study revealed that CFD is the best tool to study detailed homogeneous and heterogeneous reaction schemes, even for complex catalyst geometries.

CFD simulation of subcooled boiling flow in PWR 5 ⨯ 5 rod bundle

Kerntechnik ◽  
2021 ◽  
Vol 86 (1) ◽  
pp. 24-32
Author(s):  
B. Ren ◽  
Y. Dang ◽  
F. J. Gan ◽  
P. Yang
Keyword(s):  
Void Fraction ◽  
Cfd Simulation ◽  
Phase Distribution ◽  
Flow Boiling ◽  
Fluid Model ◽  
Three Dimensional ◽  
Spacer Grid ◽  
Pressurized Water ◽  
Rod Bundle ◽  
Boiling Flow

Abstract This paper describes the computational fluid dynamics (CFD) methodology to simulate the boiling flow in a typical Pressurized Water Reactor (PWR) 5 ⨯ 5 rod bundle. The method includes the Eulerian-Eulerian two-fluid model coupled with the improved wall heat partitioning model. The NUPEC PWR Subchannel and Bundle Test (PSBT) International Benchmark are used for validation. The simulated surface averaged void fraction agree well with the experimental data, which indicate the promising application of the present method for modeling the boiling flow in the fuel rod bundle. The main emphasis of current research has been given to the analysis of the phase distribution around and downstream the spacer grid, the effect of the spacer grid structure, including the mixing vanes, the springs and the dimples on the void fraction distribution is investigated. The findings can contribute to a better understanding of three dimensional flow boiling characteristics and can be used to assist in optimizing the spacer grid.

An experimentally verified three-dimensional non-stationary fluid model of unloaded atmospheric pressure inductively coupled plasmas

2020 ◽  
Vol 53 (45) ◽  
pp. 455203
Author(s):  
I V Tsivilskiy ◽  
A Kh Gilmutdinov ◽  
S A Nikiforov ◽  
R S Rublya ◽  
B A Khamidullin ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Fluid Model ◽  
Three Dimensional ◽  
Inductively Coupled Plasmas ◽  
Inductively Coupled ◽  
Coupled Plasmas

scholarly journals Simulation and measurement of air quality in the traffic congestion area

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Shin Yu ◽  
Chang Tang Chang ◽  
Chih Ming Ma
Keyword(s):  
Air Quality ◽  
Traffic Congestion ◽  
Traffic Management ◽  
Reference Model ◽  
Dispersion Model ◽  
Fluid Model ◽  
Three Dimensional ◽  
Vehicle Speed ◽  
Management Plans ◽  
Dimensional Distribution

AbstractThe traffic congestion in the Hsuehshan tunnel and at the Toucheng interchange has led to traffic-related air pollution with increasing concern. To ensure the authenticity of our simulation, the concentration of the last 150 m in Hsuehshan tunnel was simulated using the computational fluid dynamics fluid model. The air quality at the Toucheng interchange along a 2 km length highway was simulated using the California Line Source Dispersion Model. The differences in air quality between rush hours and normal traffic conditions were also investigated. An unmanned aerial vehicle (UAV) with installed PM2.5 sensors was developed to obtain the three-dimensional distribution of pollutants. On different roads, during the weekend, the concentrations of pollutants such as SOx, CO, NO, and PM2.5 were observed to be in the range of 0.003–0.008, 7.5–15, 1.5–2.5 ppm, and 40–80 μg m− 3, respectively. On weekdays, the vehicle speed and the natural wind were 60 km h− 1 and 2.0 m s− 1, respectively. On weekdays, the SOx, CO, NO, and PM2.5 concentrations were found to be in the range of 0.002–0.003, 3–9, 0.7–1.8 ppm, and 35–50 μg m− 3, respectively. The UAV was used to verify that the PM2.5 concentrations of vertical changes at heights of 9.0, 7.0, 5.0, and 3.0 m were 45–48, 30–35, 25–30, and 50–52 μg m− 3, respectively. In addition, the predicted PM2.5 concentrations were 40–45, 25–30, 45–48, and 45–50 μg m− 3 on weekdays. These results provide a reference model for environmental impact assessments of long tunnels and traffic jam-prone areas. These models and data are useful for transportation planners in the context of creating traffic management plans.

scholarly journals A Three-Dimensional Numerical and Multi-Objective Optimal Design of Wavy Plate-Fins Heat Exchangers

Processes ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 9
Author(s):  
Chao Yu ◽  
Xiangyao Xue ◽  
Kui Shi ◽  
Mingzhen Shao
Keyword(s):  
Heat Exchangers ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Basis Functions ◽  
Approximation Model ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Multi Objective Genetic Algorithm ◽  
Colburn Factor ◽  
Heat Exchange Efficiency

This paper presents a method for optimizing wavy plate-fin heat exchangers accurately and efficiently. It combines CFD simulation, Radical Basis Functions (RBF) with multi-objective optimization to improve the performance. The optimization of the Colburn factor j and the friction coefficient f is regarded as a multi-objective optimization problem, due to the existence of two contradictory goals. The approximation model was obtained by Radical Basis Functions, and the shape of the heat exchanger was optimized by multi-objective genetic algorithm (MOGA). The optimization results showed that j increased by 17.62% and f decreased by 20.76%, indicating that the heat exchange efficiency was significantly enhanced and the fluid structure resistance reduced. Then, from the aspects of field synergy and tubulence energy, the performance advantage of the optimized structure was further confirmed.

Three-dimensional CFD simulation of anaerobic reactions in a continuous packed-bed bioreactor

2021 ◽  
Author(s):  
Sasan Zarei ◽  
Seyyed Mohammad Mousavi ◽  
Teimour Amani ◽  
Mehrdad Khamforoush ◽  
Arezou Jafari
Keyword(s):  
Cfd Simulation ◽  
Three Dimensional ◽  
Packed Bed ◽  
Packed Bed Bioreactor

Analysis of a Virtual Prototype First-Stage Rotor Blade Using Integrated Computer-Based Design Tools

2006 ◽  
Author(s):  
Michel Arnal ◽  
Christian Precht ◽  
Thomas Sprunk ◽  
Tobias Danninger ◽  
John Stokes
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Thermal Loading ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Life Assessment ◽  
Element Analysis ◽  
Pressure Losses ◽  
Cooling Channels ◽  
Internally Cooled

The present paper outlines a practical methodology for improved virtual prototyping, using as an example, the recently re-engineered, internally-cooled 1st stage blade of a 40 MW industrial gas turbine. Using the full 3-D CAD model of the blade, a CFD simulation that includes the hot gas flow around the blade, conjugate heat transfer from the fluid to the solid at the blade surface, heat conduction through the solid, and the coolant flow in the plenum is performed. The pressure losses through and heat transfer to the cooling channels inside the airfoil are captured with a 1-D code and the 1-D results are linked to the three-dimensional CFD analysis. The resultant three-dimensional temperature distribution through the blade provides the required thermal loading for the subsequent structural finite element analysis. The results of this analysis include the thermo-mechanical stress distribution, which is the basis for blade life assessment.

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