Vibratory Finishing of Immobilized Cylinders

2012 ◽  
Vol 565 ◽  
pp. 278-283 ◽  
Author(s):  
Stephen Wan ◽  
Takashi Sato ◽  
Andry Hartawan
Keyword(s):  
Surface Roughness ◽  
Flow Field ◽  
Granular Flow ◽  
Flow Direction ◽  
General Purpose ◽  
Vibratory Finishing ◽  
Cfd Simulations ◽  
Dense Granular Flow ◽  
The Media ◽  
Computational Fluid Dynamics Cfd

We report preliminary results from an on-going study investigating the effect of fixing workpieces within the media flow field contained in a typical vibratory finishing bowl. To this end, we studied the surface roughness evolution over the surfaces of workpieces with generic geometries such as cylinders. A granular flow dynamics model applicable to dense granular flow and a previously derived process equation were invoked in order to respectively describe the flow of the abrasive media; and the roughness distribution in terms of the granular pressure and velocity. By solving the granular flow field for the pressure and velocity distribution on a given geometry using a general purpose computational fluid dynamics (CFD) code, we were able to analyse changes in surface roughness distribution from the process equation. The immobilized cylinders were submerged in the top portion of the media flow field so as to facilitate comparison between media flow past the workpieces as experimentally observed and as predicted by the CFD simulations. We conclude with an analysis, based on both experimental and predicted results, of the way in which media flow direction biases the surface roughness distribution on an immobilized cylinder.

scholarly journals Crude Oil Fouling in Heat Exchangers: A Study on Effects of Influencing Forces

2021 ◽  
Vol 287 ◽  
pp. 03003
Author(s):  
Sampath Emani ◽  
M. Ramasamy ◽  
Ku Zilati Ku Shaari
Keyword(s):  
Surface Roughness ◽  
Crude Oil ◽  
Flow Velocity ◽  
Deposition Rate ◽  
Heat Exchangers ◽  
Cfd Simulations ◽  
Deposition Velocities ◽  
Computational Fluid Dynamics Cfd ◽  
Lower Temperature ◽  
Oil Fouling

One of the major concerns in petroleum refinery preheat trains is identified as fouling. Fouling impacts the refinery economics and environment heavily. Various approaches to mitigate fouling have not yielded the desired results. This is due to lack of understanding on the effect of influencing forces on crude oil fouling in heat exchangers. Therefore, this study attempts to investigate the effects of various forces such as gravity, Saffman Lift, drag and thermophoretic on crude oil fouling in heat exchangers through Computational Fluid Dynamics (CFD) simulations. From the simulations, it is observed that the higher particle size and particle concentration resulted in higher deposition of particles. Deposition velocities increase for larger sized particles and decrease for small and medium sized particles. The Increased flow velocities and surface roughness increases wall shear and mitigate fouling. Lower temperature gradients at the heat exchanger surface decreases deposition rates due to high thermophoretic forces. The mass deposition rate is reduced by 10.3 and 16.9% with 0.03 and 0.05 Pa, respectively, for 0.14 m/s flow velocity. Also, the mass deposition rate is reduced by 15.6 and 25.1% with 0.03 and 0.05 Pa, respectively, for 0.47 m/s flow velocity. With increased surface roughness from 0.03 to 0.05 mm, the mass deposition rate is reduced by 11.48 and 19.18%, respectively, for 0.14 m/s flow velocity. Also, for 0.47 m/s flow velocity, the mass deposition rate is reduced by 18.84 and 32.92% for 0.03- and 0.05-mm surface roughness, respectively.

Validation of a 2D CFD Model for Hydrodynamics' Studies in CIJ Mixers

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Ricardo J. Santos ◽  
André M. Teixeira ◽  
Ertugrul Erkoç ◽  
Mohamed Sultan ◽  
Anna M Karpinska ◽  
...  
Keyword(s):  
Flow Field ◽  
Impinging Jets ◽  
Cfd Model ◽  
Operational Parameters ◽  
3D Flow ◽  
Cfd Simulations ◽  
Mixing Chamber ◽  
Validity Range ◽  
Computational Fluid Dynamics Cfd ◽  
2D Model

A 2D model of a confined impinging jets mixer having the same geometry of the mixing chamber of a Reaction Injection Moulding, RIM, machine is introduced for the flow field simulation in a Computational Fluid Dynamics, CFD, code. From the CFD simulations the flow field structures and dynamics are clearly established. In addition, the numerical parameters affecting the 2D model simulations are studied, setting for each parameter a validity range. The 2D model is validated and used in the study of some operational parameters: the Reynolds number, the Froude number and the momentum ratio between the opposed jets. The validation of the CFD simulations is also made by comparison with experimental results. The limitations of the 2D model, for simulating the actual 3D flow field, are assessed; from the 2D/3D comparison, it is clearly shown that the introduced model can predict the main flow field features.

Test and Simulation of the Effects of Surface Roughness on a Shrouded Centrifugal Impeller

2014 ◽  
Author(s):  
William T. Cousins ◽  
Lei Yu ◽  
Jacquelynn Garofano ◽  
Barbara Botros ◽  
Vishnu Sishtla ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Cfd Simulation ◽  
Centrifugal Impeller ◽  
Test Results ◽  
Cfd Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
The Common ◽  
R Value ◽  
The Impact ◽  
Grain Roughness

Surface roughness is an important parameter in the operational efficiency and loss development of turbomachinery components. Many computational fluid dynamics (CFD) simulations are performed on turbomachinery, but often one of the common assumptions is that the surfaces are hydraulically smooth. In this work, examination of the surfaces of two cast impellers is performed and compared to machined impellers with smoother surfaces. Both impeller sets were run in a two-stage industrial chiller unit using R134a refrigerant. Test results are presented and the impact of surface roughness modeling on the design is reviewed. Also discussed is the theory of the impact of roughness on turbulent boundary layers. Details about providing the CFD simulation with the proper sand grain roughness is discussed when surface finish (R-value) in microinches (μin) is measured.

scholarly journals Intensification of liquid mixing and local turbulence using a fractal injector with staggered conformation

2021 ◽  
Author(s):  
Shuxian Jiang ◽  
Marc-Olivier Coppens ◽  
Jia-Jun WANG
Keyword(s):  
Flow Field ◽  
Operating Conditions ◽  
Cfd Simulations ◽  
Mixing Performance ◽  
Double Ring ◽  
Spatially Distributed ◽  
Field Uniformity ◽  
Reaction Region ◽  
Dissipation Model ◽  
Computational Fluid Dynamics Cfd

Two self-similar, tree-like injectors of the same fractal dimension are compared, demonstrating that other geometric parameters besides dimension play a crucial role in determining mixing performance. In one injector, when viewed from the top, the conformation of branches is eclipsed; in the other one, it is staggered. The flow field and the fractal injector induced mixing performance are investigated through computational fluid dynamics (CFD) simulations. The finite rate/eddy dissipation model (FR/EDM) is modified for fast liquid-phase reactions involving local micromixing. Under the same operating conditions, flow field uniformity and micromixing are improved when a staggered fractal injector is used. This is because of enhanced jet entrainment and local turbulence around the spatially distributed nozzles. Compared with a traditional double-ring sparger, a larger reaction region volume and lower micromixing time are obtained with fractal injectors. Local turbulence around the spatially distributed nozzles in fractal injectors improves reaction efficiency.

scholarly journals Aerodynamics Analysis of Speed Skating Helmets: Investigation by CFD Simulations

2021 ◽  
Vol 11 (7) ◽  
pp. 3148
Author(s):  
Guillermo Puelles Magán ◽  
Wouter Terra ◽  
Andrea Sciacchitano
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Numerical Simulations ◽  
Turbulence Model ◽  
Aerodynamic Drag ◽  
Cfd Simulations ◽  
Speed Skating ◽  
Computational Fluid Dynamics Cfd ◽  
Rans Simulations

In this work, we investigate the flow field around speed skating helmets and their associated aerodynamic drag by means of computational fluid dynamics (CFD) simulations. An existing helmet frequently used in competition was taken as a baseline. Six additional helmet designs, as well as the bare-head configuration, were analysed. All the numerical simulations were performed via 3D RANS simulations using the SST k-ω turbulence model. The results show that the use of a helmet always reduces the aerodynamic drag with respect to the bare head configuration. Besides, an optimised helmet design enables a reduction of the skaters aerodynamic drag by 5.9%, with respect to the bare-head configuration, and by 1.6% with respect to the use of the baseline Omega helmet.

scholarly journals Numerical Simulation of Internal Loop Reactor for Heavy Oil Slurry Bed Hydroprocessing

2014 ◽  
Vol 7 (1) ◽  
pp. 47-54
Author(s):  
Sun Lanyi ◽  
Wang Jian ◽  
Bai Fei ◽  
Bo Shoushi
Keyword(s):  
Flow Field ◽  
Heavy Oil ◽  
Flow Model ◽  
Scale Up ◽  
Cfd Simulations ◽  
Two Phase ◽  
Loop Reactor ◽  
Internal Loop ◽  
Commercial Code ◽  
Computational Fluid Dynamics Cfd

Computational Fluid Dynamics (CFD) simulations of internal loop reactor for heavy oil slurry bed hydroprocessing have been done in commercial code Fluent 6.3 using Euler two-phase flow model and standard k-ε turbulence model. The effects of the physical properties on the flow field in the reactor are investigated. The results show that the gas density has little effect but the liquid viscosity has a significant effect on flow field and gas hold-up. An analysis of the effect of reactor structures and scale-up on the flow field and gas hold-up are also provided, and optimal structure is obtained through simulations. The conclusions obtained in this paper have great significance for the slurry bed hydrocracking process.

scholarly journals Using Computational Fluid Dynamics to Simulate Flow Fields from various Melt Blowing Dies

2005 ◽  
Vol os-14 (1) ◽  
pp. 1558925005os-14
Author(s):  
Holly M. Krutka ◽  
Robert L. Shambaugh ◽  
Dimitrios V. Papavassiliou
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Flow Fields ◽  
Melt Blowing ◽  
Cfd Simulations ◽  
Flow Field Characteristics ◽  
Computational Fluid Dynamics Cfd ◽  
The Common

This paper is an investigation of the flow fields generated by dual rectangular jets. Specifically, the jets examined are the same as the common slot dies used in the industrial melt blowing process. In this process, a molten polymer is attenuated by air discharging from dual jets. The velocity and turbulence of these flow fields determine the rate and quality of polymer fiber production. The flow field characteristics can be simulated quickly and efficiently using computational fluid dynamics (CFD). These CFD simulations require the use of an appropriate length scale to describe the flow field. This paper describes how these CFD simulations can be used to compare the flow fields generated by different jet geometries.

scholarly journals Realistic boundary conditions in SimVascular through inlet catheter modeling

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Amirtahà Taebi ◽  
Selin Berk ◽  
Emilie Roncali
Keyword(s):  
Boundary Condition ◽  
Flow Field ◽  
Cfd Simulation ◽  
Arterial Tree ◽  
Cfd Simulations ◽  
Tumor Embolization ◽  
Liver Cancer Patient ◽  
Mesh Density ◽  
Flow Velocity Profile ◽  
Computational Fluid Dynamics Cfd

Abstract Objective This study aims at developing a pipeline that provides the capability to include the catheter effect in the computational fluid dynamics (CFD) simulations of the cardiovascular system and other human vascular flows carried out with the open-source software SimVascular. This tool is particularly useful for CFD simulation of interventional radiology procedures such as tumor embolization where estimation of a therapeutic agent distribution is of interest. Results A pipeline is developed that generates boundary condition files which can be used in SimVascular CFD simulations. The boundary condition files are modified such that they simulate the effect of catheter presence on the flow field downstream of the inlet. Using this pipeline, the catheter flow, velocity profile, radius, wall thickness, and deviation from the vessel center can be defined. Since our method relies on the manipulation of the boundary condition that is imposed on the inlet, it is sensitive to the mesh density. The finer the mesh is (especially around the catheter wall), the more accurate the velocity estimations are. In this study, we also utilized this pipeline to qualitatively investigate the effect of catheter presence on the flow field in a truncated right hepatic arterial tree of a liver cancer patient.

scholarly journals Streaming Birefringence - A Step Forward

2008 ◽  
Vol 13-14 ◽  
pp. 23-28 ◽  
Author(s):  
T. Spalton ◽  
Rachel A Tomlinson ◽  
A.E. Garrard ◽  
S.B.M. Beck
Keyword(s):  
Fluid Dynamics ◽  
Aqueous Solution ◽  
Flow Field ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Shear Stresses ◽  
Cfd Simulations ◽  
Full Field ◽  
Phase Stepping ◽  
Computational Fluid Dynamics Cfd

An investigation into three dimensional fluid flow has been conducted which combines the use of Computational Fluid Dynamics (CFD) simulations with the experimental phenomenon of Streaming Birefringence. A versatile flow channel was designed and built for use in conjunction with a circular polariscope. The experimental liquid used was an aqueous solution of a dye, commercially known as Milling Yellow NGS with the addition of Sodium Chloride. To extract the flow fields, six image phase stepping photoelasticity was used over backward and forward steps, and flows around a cylinder, and full-field fringe data were obtained. This method needs laminar flow regimes and the Reynolds number of the flow was around 10. To allow direct comparisons of the CFD solutions with the optical results, a macro (UDF) was written to interpret the flow field results from a (FLUENT6) CFD simulation. This integrated the shear stresses across the flow field and banded the results into fringes. A good correlation between the simulated fringes and the shearstrain rate was obtained from these observations.

Flow Field Prediction and Bubble Trajectory Model in Gas-Liquid Cylindrical Cyclone (GLCC) Separators

1999 ◽  
Vol 121 (1) ◽  
pp. 9-14 ◽  
Author(s):  
I. Mantilla ◽  
S. A. Shirazi ◽  
O. Shoham
Keyword(s):  
Flow Field ◽  
Flow Model ◽  
Mechanistic Models ◽  
Cfd Simulations ◽  
Trajectory Model ◽  
Swirl Intensity ◽  
Cylindrical Cyclone ◽  
Fluid Properties ◽  
Inlet Geometry ◽  
Computational Fluid Dynamics Cfd

Several mechanistic models have been already developed for predicting the onset of liquid carryover in gas-liquid cylindrical cyclone (GLCC) separators. However, currently no model is available to predict gas carryunder. A bubble trajectory model has been developed that can be used to determine the initiation of gas carryunder in the GLCC and to design GLCC for field applications. The bubble trajectory model uses a predicted flow field in GLCC that is based on swirl intensity. This paper describes the development of a general correlation to predict the decay of the swirl intensity. The correlation accounts for the effects of fluid properties (Reynolds number) as well as inlet geometry. Available experimental data as well as computational fluid dynamics (CFD) simulations were used to validate the correlation. The swirl intensity is used to calculate the local axial and tangential velocities. The flow model and improved bubble trajectory results agree with experimental observation and CFD results. Examples are provided to show how the bubble trajectory model can be used to design GLCC.

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