scholarly journals OVERVIEW OF NUMERICAL METHODS FOR SIMULATING RANQUE-HILSCH EFFECT WITHIN VORTEX TUBES / LIETUVOS KARJERŲ UŽPILDŲ POVEIKIO BETONO ŠARMINEI KOROZIJAI TYRIMAI

2016 ◽  
Vol 7 (5) ◽  
pp. 571-576
Author(s):  
Vadim Nikitin ◽  
Paulius Bogdevičius ◽  
Marijonas Bogdevičius
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Vortex Tube ◽  
Geometric Model ◽  
Governing Equations ◽  
Computational Fluid Dynamics Cfd ◽  
The Subject ◽  
Published Research ◽  
Vortex Tubes ◽  
Good Agreement

The main goal of this paper is to present a summarized overview of the methods used for Ranque–Hilsch vortex tube numerical analysis using computational fluid dynamics (CFD). The overview is mainly focused on the most recently conducted studies that are both backed by experimental data and is evaluated by the authors as being in good agreement with experimental results. Generalized tendencies in computational vortex tube analysis are presented while focusing on researchers’ approach towards the geometric model used for the study and the governing equations. A brief introduction to the subject matter is presented followed by a short retrospective of the previous studies and related challenges. The conclusions are formed based on the most recent, as well as previously analysed, published research results. Užpildų šarminė korozija betone vyksta reaguojant cemente esantiems natrio ir kalio hidroksidams (šarmams) su aktyviu SiO2, esančiu kai kuriuose užpilduose. Vykstant šiai reakcijai betone susidaro didelių vidinių įtempių, kurie sukelia betono deformacijas, pleišėjimą ir suirimą. Reakcija vyksta lėtai, betono irimo požymių atsiranda tik po kelių mėnesių ar metų. Tyrimams buvo naudojami dviejų skirtingų karjerų užpildai. Atlikus tyrimus nustatyta, kad Lietuvos žvyro karjerai užteršti reaktyviomis dalelėmis, turinčiomis amorfinio silicio dioksido, reaguojančio su cemente esančiais natrio ir kalio šarmais, ir sukeliančiomis betono šarminę koroziją. Nustatyta, kad pagal AAR 2 stambieji užpildai priskiriami II grupei – galimai reaktyviems užpildams, nes jų plėtra po 14 parų viršija 0,1 %.

scholarly journals Investigating the Effect of Heterogeneous Hull Roughness on Ship Resistance Using CFD

2021 ◽  
Vol 9 (2) ◽  
pp. 202
Author(s):  
Soonseok Song ◽  
Yigit Kemal Demirel ◽  
Claire De Marco Muscat-Fenech ◽  
Tonio Sant ◽  
Diego Villa ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Reynolds Number ◽  
Shear Stress ◽  
Flow Characteristics ◽  
Cfd Simulations ◽  
Ship Resistance ◽  
Wigley Hull ◽  
Computational Fluid Dynamics Cfd ◽  
Good Agreement

Research into the effects of hull roughness on ship resistance and propulsion is well established, however, the effect of heterogeneous hull roughness is not yet fully understood. In this study, Computational Fluid Dynamics (CFD) simulations were conducted to investigate the effect of heterogeneous hull roughness on ship resistance. The Wigley hull was modelled with various hull conditions, including homogeneous and heterogeneous hull conditions. The results were compared against existing experimental data and showed a good agreement, suggesting that the CFD approach is valid for predicting the effect of heterogeneous hull roughness on ship resistance. Furthermore, the local distributions of the wall shear stress and roughness Reynolds number on the hull surface were examined to assess the flow characteristics over the heterogeneous hull roughness.

scholarly journals Application of CFD to the Design of Multirun Meter Station With Ultrasonic Meters

1998 ◽  
Author(s):  
Jaroslaw Jelen ◽  
Wojciech Studzinski ◽  
Michael Brown
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Numerical Simulation ◽  
Numerical Model ◽  
Experimental Information ◽  
Out Of Plane ◽  
Ultrasonic Flow Meter ◽  
Computational Fluid Dynamics Cfd ◽  
Good Agreement ◽  
Subsequent Integration

Designers of ultrasonic meter stations with headers do not have any experimental data which can help to determine proper location of the multipath ultrasonic meter within the meter run. The results of meter tests are limited to such configurations as a single 90° elbows and two elbows out of plane. Because of the variety of header layouts used in practice any experimental information related to this piping configuration will be of limited use in the design process. The proposed approach is based on the application of Computational Fluid Dynamics (CFD) methods to the evaluation of header effects on ultrasonic flow meter using a commercial CFD code combined with a numerical model of the ultrasonic meter. The numerical simulation of the flow field in the header and meter runs and subsequent integration of the obtained velocity field in a numerical model of multipath ultrasonic meter were used to determine the optimal meter position. This approach was validated against available experimental data on the ultrasonic meter performance downstream of single and double elbow. The comparison of simulations and test data has shown very good agreement of trends exhibited by the meter. The trends were replicated by the simulator within approximately 1% for X/D ≥5 and within 0.5% for X/D ≥9.

Numerical Uncertainty in Fluid Flow Calculations: Needs for Future Research

1993 ◽  
Vol 115 (2) ◽  
pp. 194-195 ◽  
Author(s):  
Ismail Celik
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Quality Control ◽  
Fluid Flow ◽  
Flow Problem ◽  
Future Research ◽  
Error Measures ◽  
Engineering Problems ◽  
Computational Fluid Dynamics Cfd ◽  
Good Agreement

Computational fluid dynamics (CFD) has established itself as a viable technique for performing research and solving engineering problems, and when used correctly, can give accurate results for many fairly complex problems. This success has led to an ever increasing number of journal publications, many code developers, and surprisingly many users in the industry. Commercial CFD packages are often marketed by claiming that a particular code can solve almost every fluid flow problem, while many users, both in industry and academia, stand aloof from quantitative error measures, instead being dazzled by colorful computer generated output. This is mostly due to insufficient education in the scientific computing discipline which often leads (intentional or not) to misuse and wrong conclusions. Every year, hundreds of papers are published in conference proceedings, and journals, on the advancement and application of CFD techniques. Whenever something is spawned in such large quantities it is very easy to lose sense of quality control. To assert quality, papers often end with a conclusion such as “good agreement is found between experiments and predictions” to which the readers have become so immune that it no longer has meaning. Unfortunately, very little information is provided about the numerical uncertainty and the experimental data are often treated as if they are 100 percent accurate.

Swirling Flow Through Venturi Tubes of Convergent Angle 10.5° and 21°

2006 ◽  
Author(s):  
Jeff Gibson ◽  
Michael Reader-Harris
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Reynolds Number ◽  
Swirling Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
Good Agreement

Computational Fluid Dynamics (CFD) was used to compute the effect of two bends in perpendicular planes on the performance of 4-inch Venturi tubes with β = 0.4, 0.6 and 0.75 for water at a Reynolds number of 350,000 and at various distances from the bend. Two types of Venturi tubes were analysed, the first having a standard convergent angle of 21°, the second having a non-standard convergent angle of 10.5°. Good agreement with experiment was obtained. Swirling axisymmetric flows were computed to help interpret experimental data.

Multiphase CFD Analysis of a Subsea Intervention System

2015 ◽  
Author(s):  
Elham Maghsoudi ◽  
Uday Godse ◽  
Alistair Gill
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Large Scale ◽  
Cfd Analysis ◽  
Cfd Models ◽  
System A ◽  
Mixing Behavior ◽  
Computational Fluid Dynamics Cfd ◽  
2D And 3D ◽  
Good Agreement

In this study, a computational fluid dynamics (CFD) analysis was conducted to evaluate a new design of an intervention system. A multiphase analysis was performed to understand the mixing characteristics as the cement is pumped into the well and the degree to which the cement could be contaminated with spacer fluid. A transient multiphase analysis was conducted to examine the flow and the mixing behavior through the various sections of the intervention system. A combination of 2D and 3D CFD models was used, depending upon the geometry in each section. The results indicated that the intervention system operates efficiently without diluting the cement. Non-Newtonian methods used in CFD were validated using available theoretical and experimental data. In a large-scale yard test, good agreement was obtained for resin and water; however, cement did not show good agreement as the flow rate increased over 1 bbl/min.

Effects of Over Fire Air on the Combustion and NOx Emission Characteristics of a 600 MW Opposed Swirling Fired Boiler

2012 ◽  
Vol 512-515 ◽  
pp. 2135-2142 ◽  
Author(s):  
Yu Peng Wu ◽  
Zhi Yong Wen ◽  
Yue Liang Shen ◽  
Qing Yan Fang ◽  
Cheng Zhang ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Empirical Method ◽  
Nox Emission ◽  
Emission Characteristics ◽  
Cfd Model ◽  
Nitrogen Release ◽  
Computational Fluid Dynamics Cfd ◽  
Low Nox Emission

A computational fluid dynamics (CFD) model of a 600 MW opposed swirling coal-fired utility boiler has been established. The chemical percolation devolatilization (CPD) model, instead of an empirical method, has been adapted to predict the nitrogen release during the devolatilization. The current CFD model has been validated by comparing the simulated results with the experimental data obtained from the boiler for case study. The validated CFD model is then applied to study the effects of ratio of over fire air (OFA) on the combustion and nitrogen oxides (NOx) emission characteristics. It is found that, with increasing the ratio of OFA, the carbon content in fly ash increases linearly, and the NOx emission reduces largely. The OFA ratio of 30% is optimal for both high burnout of pulverized coal and low NOx emission. The present study provides helpful information for understanding and optimizing the combustion of the studied boiler

The Effect of Turbulence and Real Gas Models on the Two Phase Spontaneously Condensing Flows in Nozzle

2013 ◽  
Author(s):  
Yogini Patel ◽  
Giteshkumar Patel ◽  
Teemu Turunen-Saaresti
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Navier Stokes ◽  
Two Phase ◽  
Real Gas ◽  
Spontaneous Condensation ◽  
Condensing Flows ◽  
Computational Fluid Dynamics Cfd

The aim of the paper is to analyse the effect of turbulence and real gas models on the process of spontaneous condensation in converging diverging (CD) nozzle by using commercial Computational Fluid Dynamics (CFD) code. The calculations were based on the 2-D compressible Navier-Stokes (NS) equations coupled with two-equation turbulence model, and the non-equilibrium spontaneous condensing steam flow was solved on the basis of the classical nucleation theory. The results were validated to the available experimental data.

scholarly journals Modelling of working processes of non-contact oil free vacuum pumps by computational fluid dynamics (CFD) methods

2021 ◽  
Vol 2059 (1) ◽  
pp. 012003
Author(s):  
A Burmistrov ◽  
A Raykov ◽  
S Salikeev ◽  
E Kapustin
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Mathematical Models ◽  
Cfd Models ◽  
Ansys Cfx ◽  
Sst Turbulence Model ◽  
Computational Fluid Dynamics Cfd ◽  
Dynamic Meshing ◽  
Comparison With Experimental Data

Abstract Numerical mathematical models of non-contact oil free scroll, Roots and screw vacuum pumps are developed. Modelling was carried out with the help of software CFD ANSYS-CFX and program TwinMesh for dynamic meshing. Pumping characteristics of non-contact pumps in viscous flow with the help of SST-turbulence model were calculated for varying rotors profiles, clearances, and rotating speeds. Comparison with experimental data verified adequacy of developed CFD models.

Computational Fluid Dynamics Techniques for Flows in Lapple Cyclone Separator

2005 ◽  
Vol 498-499 ◽  
pp. 179-185
Author(s):  
A.F. Lacerda ◽  
Luiz Gustavo Martins Vieira ◽  
A.M. Nascimento ◽  
S.D. Nascimento ◽  
João Jorge Ribeiro Damasceno ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Turbulent Flow ◽  
Reynolds Stress ◽  
Cyclone Separator ◽  
Two Dimensional ◽  
Stress Components ◽  
Computational Fluid Dynamics Cfd

A two-dimensional fluidynamics model for turbulent flow of gas in cyclones is used to evaluate the importance of the anisotropic of the Reynolds stress components. This study presents consisted in to simulate through computational fluid dynamics (CFD) package the operation of the Lapple cyclone. Yields of velocity obtained starting from a model anisotropic of the Reynolds stress are compared with experimental data of the literature, as form of validating the results obtained through the use of the Computational fluid dynamics (Fluent). The experimental data of the axial and swirl velocities validate numeric results obtained by the model.

Analysis and Numerical Simulation of no Reacting Swirling Flow by Using URANS Approach

2021 ◽  
Vol 57 ◽  
pp. 67-79
Author(s):  
Merouane Habib ◽  
Senouci Mohammed
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Swirling Flow ◽  
Navier Stokes ◽  
Governing Equations ◽  
Simulation Based ◽  
Classical Models ◽  
Recirculation Zones ◽  
Computational Fluid Dynamics Cfd ◽  
Volume Method

In this paper, we investigate the no-reacting swirling flow by using the numerical simulation based to the unsteady Reynolds-averaged Navier-Stokes approach. The numerical simulation was realized by using a computational fluid dynamics CFD code. The governing equations are solved by using the finite volume method with two classical models of turbulence K-epsilon and Shear Stress K-ω. The objective of this paper is therefore to evaluate the performance of the two models in predicting the recirculation zones in a swirled turbulent flow. The current models are validated by comparing the numerical results of the axial, radial and tangential velocities to the experimental data from literature.

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