scholarly journals Computational modeling of gas mixture dispersion in a dynamic setup – 2d and 3d numerical approach

2018 ◽  
Vol 44 ◽  
pp. 00146 ◽  
Author(s):  
Andrzej Polanczyk ◽  
Zdzisław Salamonowicz
Keyword(s):  
Fluid Model ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Chlorine Concentration ◽  
Gas Mixture ◽  
Circular Profile ◽  
Volume Of Fluid Model ◽  
Two Stages ◽  
2D And 3D

The aim of the study was to prepare a mathematical model of gas mixture dispersion with the use of Computational Fluid Dynamic (CFD) technique. Three dimensional chlorine dispersion in a dynamic setup with the use of Volume of Fluid model (VOD) model was applied. The area of investigation was equal to 0.1km2 and the high of the mathematical domain was equal to 50m. Atmosphere was considered in two stages: as one direction of wind flow and no wind. Comparison of constant and dynamic conditions indicated high impact of wind. For the windless case circular profile of chlorine concentration around dispersion source was observed. While, for the wind application the main chlorine concentration moved ahead the source of dispersion.

HELIOS Code Simulation of Condensation Induced Hydrogen Accumulation in Slightly Inclined Non-Vented Pipe

2004 ◽  
Author(s):  
Vladimir Stevanovic ◽  
Zoran Stosic ◽  
Uwe Stoll
Keyword(s):  
Heat Loss ◽  
Fluid Model ◽  
Three Dimensional ◽  
Mass Conservation ◽  
Transport Processes ◽  
Gas Mixture ◽  
Ambient Atmosphere ◽  
Horizontal Pipe ◽  
Heat Loss Rate ◽  
Parametric Analyses

The radiolytic gases (hydrogen and oxygen) accumulation in a gas mixture with steam, due to the steam condensation in a nearly horizontal pipe, closed at one end and open at the other, is simulated and analyzed with the HELIOS code. The thermal-hydraulic and physico-chemical code HELIOS is based on three-dimensional two-fluid model of steam, hydrogen and oxygen gas mixture and water condensate flow, as well as on the radiolytic gases mass conservation equations. Transport processes at the gas mixture-water condensate interface are modelled with appropriate closure laws. Obtained results show that the occurrence of the radiolytic gases accumulation in the non-vented horizontal pipe depends on the complex influence of several parameters such as pipe diameter, thermo-physical properties of gas mixture and condensate and heat loss rate from the gas mixture to the ambient atmosphere. Performed parametric analyses show that under lower heat loss rates or higher pipe diameters, the hydrogen-oxygen accumulation does not occur due to the buoyancy driven circulation of the gas mixture, which expels the gas mixture stream with the higher radiolytic gases concentration out of the pipe. This behavior is opposite to the hydrogen and oxygen accumulation in the vertical pipe closed at the top and open at the bottom, where the front of the accumulated radiolytic gases always propagates from the pipe top.

Investigation on the function of double tipping bucket for improvement of rainfall measurement

2020 ◽  
Author(s):  
Cai Zhao ◽  
Liu Jiufu ◽  
Liu Hongwei ◽  
Liao Aimin ◽  
Liao Minhan
Keyword(s):  
Rainfall Intensity ◽  
Fluid Model ◽  
Fluid Dynamic ◽  
Systematic Errors ◽  
Rain Gauge ◽  
Water Volume ◽  
Dynamic Simulations ◽  
Mesh Method ◽  
Volume Of Fluid Model ◽  
Simulation Results

<p>The double-tipping bucket rain gauge (SL3-1) is widely used in meteorological stations to minimize the systematic errors by the influence of rainfall intensity on TBRs in China. With two tipping buckets, the upper tipping bucket turns over and injects rainwater into the converging funnel, and the lower tipping bucket can record the rainfall. In this study, CFD (computational fluid dynamic) simulations and experiments were performed to investigate the function of the double tipping bucket for TBRs in different rainfall intensity. In simulation, the volume-of-fluid model and Reynolds-averaged Navier–Stokes realizable k-ε model and dynamic mesh method were used. In experiments, electric balances, with accuracy of 0.001 g, were used to determine the water volume of the upper tipping bucket outflow. It shows that, with a converging funnel, natural precipitation is uniformed at a certain intensity around 1.9mm/min to control the rainwater outflow into blow tipping bucket to measure rainfall and reduce systematic errors caused by different precipitation intensities. Experimental results demonstrate that the outflow curve of the upper tipping bucket has high correspond with simulation results in tipping process. These results can provide knowledge of advantages of double tipping bucket rain gauge in rainfall measurement and improve the structure designs of double tipping bucket for TBRs and obtain more accurate rainfall data.</p>

Experimental and Numerical Approach to Enlargement and Determination of Performance of Primary Sedimentation Basin

2007 ◽  
Author(s):  
A. M. Razmi ◽  
B. Firoozabadi
Keyword(s):  
Numerical Scheme ◽  
Fluid Model ◽  
Settling Tank ◽  
Numerical Approach ◽  
Acoustic Doppler Velocimeter ◽  
Two Phase ◽  
Optimum Position ◽  
Volume Of Fluid Model ◽  
Volume Method

In the present study, the presence of a baffle and its effect on the hydrodynamics of the flow in a primary settling tank has been investigated experimentally by ADV (Acoustic Doppler Velocimeter). On the other hand, the characteristics of this flow field were simulated by an unsteady two-phase finite volume method, and VOF (Volume of Fluid) model; and results were evaluated by the experimental data. The numerical calculation performed by using k–ε RNG model agrees well with experiments. It depicts the ability of this method in predicting the velocity profile and flow structure. In addition, the optimum position of the baffle to achieve the best performance of the tank was determined by applying the above mentioned numerical scheme.

Research on Swirl-Core Nozzle with Adjustable Spray Angle Based on Vortex Theory

2010 ◽  
Vol 37-38 ◽  
pp. 1082-1087
Author(s):  
An Hong Bao ◽  
Ming Jin Yang ◽  
Xing Dai ◽  
Zhen Yu Qiu ◽  
Shou Yong Xie
Keyword(s):  
Fluid Model ◽  
Fluid Dynamic ◽  
Structural Parameters ◽  
Helix Angle ◽  
Spray Angle ◽  
Spiral Groove ◽  
Swirl Chamber ◽  
Vortex Theory ◽  
Volume Of Fluid Model ◽  
Nozzle Opening

According to Vortex Theory, the fluid flow in a swirl-core nozzle was analyzed, and an equation of spray angle was presented. The fluid in this nozzle was simulated by Volume of Fluid Model through CFD. The fluid dynamic simulation results show that diameters of nozzle opening and swirl chamber, area of spiral groove, and helix angle of the spiral groove affect the spray angle. There are optimum structural parameters for a swirl-core nozzle, and the spray angle can be adjusted by changing the depth of the swirl chamber with fixed structural parameters of the nozzle.

A Numerical Approach for the Design of the Compressor Impeller Exit Diameter Variations in a Marine Engine Turbocharger

2005 ◽  
Author(s):  
Hong-Won Kim ◽  
Seung-Hyup Ryu ◽  
Sang-Hak Ghal ◽  
Ji-Soo Ha ◽  
Sang-Ki Lee
Keyword(s):  
Pressure Ratio ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Medium Speed ◽  
Compressor Impeller ◽  
Marine Engines ◽  
Simple Change ◽  
Fluid Flow Analysis ◽  
Two Stages

A turbocharger has been designed to fulfill the requirements of medium speed marine engines, 900 kW output power at nominal operation point. The main objective of the design was to meet the requirements of engine power and increased engine operating range. This must be achieved by improving the degree of aerodynamic efficiency and the pressure ratio. The design was performed by the two stages. First, quasi-two dimensional program code was used to determine the main geometry of the compressor. Second, the detailed geometries of compressor blade were completed by using a three dimensional fluid flow analysis. The analyzed performance results were compared with the experimental data for the verification of their validity. Also, the designed three different impeller exits allow for a substantial performance variation. Increased compression ratio and mass flow rate of new optimized impeller were 10.08 and 27.3 percent higher than those of origin impeller, respectively. This simple change of design parameter offers considerable advantages to customers when upgrading their engines.

scholarly journals Two- and Three-Dimensional Numerical Experiments Representing Two Limiting Cases of an In-Line Pair of Finger Seal Components

2003 ◽  
Vol 9 (3) ◽  
pp. 171-179 ◽  
Author(s):  
M. J. Braun ◽  
V. V. Kudriavtsev ◽  
B. M. Steinetz ◽  
M. P. Proctor
Keyword(s):  
Solid Mechanics ◽  
Stokes Equations ◽  
Fluid Model ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Navier Stokes ◽  
Line Pair ◽  
Navier Stokes Equations ◽  
Flowing Fluid ◽  
Elemental Component

The work presented here concerns the numerical development and simulation of the flow, pressure patterns, and motion of a pair of fingers arranged one behind the other and axially aligned in line. The fingers represent the basic elemental component of a finger seal and form a tight seal around the rotor. Yet their flexibility allows compliance with rotor motion and, in a passive-adaptive mode, compliance with the hydrodynamic forces induced by the flowing fluid. Although this article does not treat the actual staggered configuration of a finger seal, the in-line arrangement represents a first step toward that final goal. The numerical two-dimensional (axial-radial) and three-dimensional results presented herein were obtained using a commercial package (CFD-ACE+). Both models use an integrated numerical approach, which couples the hydrodynamic fluid model based on Navier-Stokes equations to the solid mechanics code that models the compliance of the fingers.

A Preliminary Analysis of a Turgo Type Turbine CFD Simulation Designed With an Integrated Dimensional Methodology

2012 ◽  
Author(s):  
Jorge Luis Clarembaux Correa ◽  
Jesús De Andrade ◽  
Miguel Asuaje
Keyword(s):  
Preliminary Analysis ◽  
Relative Velocity ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Hydrodynamic Performance ◽  
Volumetric Fraction ◽  
Hydrodynamic Parameters ◽  
Simulation Results ◽  
2D And 3D

A useful methodology in the design of a Turgo Type Turbine (TTT) has been accomplished through the theoretical calculation of the runner performance and efficiency, using 1D, 2D and 3D theory with certain simpliflying assumptions. The adaptation of several geometric and hydrodynamic parameters into the solution of the Rankine ovoids streamlines function, a three-dimensional potential flow, resulted in the design of a three dimensional TTT runner. A significant CFD simulation of this turbine was achieved, showing its hydrodynamic performance and the behaviour of the streamlines path through the buckets hit by the jet. The distribution of the water volumetric fraction was reported from the nozzle to the buckets In the same way, this numerical approach described the evolution of the velocity vectors from the water crossing the buckets. Furthermore, a comparison between the relative velocity angles from the three dimensional potential theory and the CFD simulation results was done, in order to find potential similarities from the water that actually passes into the buckets.

Modeling and Assessment of the Produced Water Discharges from Offshore Petroleum Platforms

2007 ◽  
Vol 42 (4) ◽  
pp. 303-310 ◽  
Author(s):  
Zhi Chen ◽  
Lin Zhao ◽  
Kenneth Lee ◽  
Charles Hannath
Keyword(s):  
Random Walk ◽  
Produced Water ◽  
Model Development ◽  
Three Dimensional ◽  
Monitoring Program ◽  
Ecological Monitoring ◽  
Numerical Approach ◽  
Ocean Model ◽  
Scale Model ◽  
Water Stream

Abstract There has been a growing interest in assessing the risks to the marine environment from produced water discharges. This study describes the development of a numerical approach, POM-RW, based on an integration of the Princeton Ocean Model (POM) and a Random Walk (RW) simulation of pollutant transport. Specifically, the POM is employed to simulate local ocean currents. It provides three-dimensional hydrodynamic input to a Random Walk model focused on the dispersion of toxic components within the produced water stream on a regional spatial scale. Model development and field validation of the predicted current field and pollutant concentrations were conducted in conjunction with a water quality and ecological monitoring program for an offshore facility located on the Grand Banks of Canada. Results indicate that the POM-RW approach is useful to address environmental risks associated with the produced water discharges.

scholarly journals Homogeneous 2D and 3D alignment of cardiomyocyte in dilated cardiomyopathy revealed by intravital heart imaging

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kiyoshi Masuyama ◽  
Tomoaki Higo ◽  
Jong-Kook Lee ◽  
Ryohei Matsuura ◽  
Ian Jones ◽  
...  
Keyword(s):  
Heart Failure ◽  
Dilated Cardiomyopathy ◽  
Cardiac Dysfunction ◽  
Three Dimensional ◽  
Single Layer ◽  
Specific Pattern ◽  
Two Dimensional ◽  
Heart Imaging ◽  
Novel Method ◽  
2D And 3D

AbstractIn contrast to hypertrophic cardiomyopathy, there has been reported no specific pattern of cardiomyocyte array in dilated cardiomyopathy (DCM), partially because lack of alignment assessment in a three-dimensional (3D) manner. Here we have established a novel method to evaluate cardiomyocyte alignment in 3D using intravital heart imaging and demonstrated homogeneous alignment in DCM mice. Whilst cardiomyocytes of control mice changed their alignment by every layer in 3D and position twistedly even in a single layer, termed myocyte twist, cardiomyocytes of DCM mice aligned homogeneously both in two-dimensional (2D) and in 3D and lost myocyte twist. Manipulation of cultured cardiomyocyte toward homogeneously aligned increased their contractility, suggesting that homogeneous alignment in DCM mice is due to a sort of alignment remodelling as a way to compensate cardiac dysfunction. Our findings provide the first intravital evidence of cardiomyocyte alignment and will bring new insights into understanding the mechanism of heart failure.

scholarly journals Vibration characteristics of triple-gear-rotor system in compressed air energy storage under variable torque load

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042098705
Author(s):  
Xinran Wang ◽  
Yangli Zhu ◽  
Wen Li ◽  
Dongxu Hu ◽  
Xuehui Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Element Model ◽  
Rotor System ◽  
Dynamic Responses ◽  
System Response ◽  
Rotating Speed ◽  
Torque Load ◽  
Set Up ◽  
Two Stages

This paper focuses on the effects of the off-design operation of CAES on the dynamic characteristics of the triple-gear-rotor system. A finite element model of the system is set up with unbalanced excitations, torque load excitations, and backlash which lead to variations of tooth contact status. An experiment is carried out to verify the accuracy of the mathematical model. The results show that when the system is subjected to large-scale torque load lifting at a high rotating speed, it has two stages of relatively strong periodicity when the torque load is light, and of chaotic when the torque load is heavy, with the transition between the two states being relatively quick and violent. The analysis of the three-dimensional acceleration spectrum and the meshing force shows that the variation in the meshing state and the fluctuation of the meshing force is the basic reasons for the variation in the system response with the torque load. In addition, the three rotors in the triple-gear-rotor system studied show a strong similarity in the meshing states and meshing force fluctuations, which result in the similarity in the dynamic responses of the three rotors.

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