scholarly journals Influences of RVG Positions on the Periodic Flow Profiles

2014 ◽  
Vol 2014 ◽  
pp. 1-17
Author(s):  
Withada Jedsadaratanachai
Keyword(s):  
Flow Behavior ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Periodic Flow ◽  
Computational Domain ◽  
Flow Area ◽  
Flow Configuration ◽  
Square Channel ◽  
Flow Profiles ◽  
Rib Vortex

The effects on the positions of rib vortex generators (RVGs) for periodic laminar flow behavior are presented numerically in three-dimensional. The RVGs with constant blockage ratio (b/H, BR = 0.15), the pitch ratio (P/H, PR = 1), and flow attack angle (α=30°) are inserted in isothermal walls of the square channel. The SIMPLE algorithm and the finite volume method (FVM) are applied for the computational domain. The influences of different gap ratios (g/H= 0–0.35) for Reynolds number based on the hydraulic diameter (Dh), Re = 100–1200, are investigated. It is found that the flow profiles can be divided into two parts; the first, similar in flow configuration, but different inu/u0values, is called “periodic flow” and the second, similar in both flow configuration andu/u0values, is called “fully developed periodic flow.” The results reveal that the periodic flow profiles appear around 2nd-3rd modules while the fully developed flow profiles occur around 6th–9th modules. In addition, the periodic flow profiles and fully developed periodic flow profiles become faster in case of the lowest continuous flow area (g/H= 0.20, 0.25, and 0.30) and the regimes close to the RVG.

Effects of Intersection Angles on Flow and Heat Transfer in Corrugated-Undulated Channels With Sinusoidal Waves

2006 ◽  
Vol 128 (8) ◽  
pp. 819-828 ◽  
Author(s):  
Jixiang Yin ◽  
Guojun Li ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Three Dimensional ◽  
Computational Domain ◽  
Straight Channel ◽  
Flow Area ◽  
Contact Points ◽  
Flow And Heat Transfer ◽  
Different Characteristics ◽  
Steady Laminar

This paper reported three-dimensional numerical simulations of the steady laminar flow and heat transfer in corrugated-undulated channels with sinusoidal waves, aiming to investigate the effects of intersection angles (θ) between corrugated and undulated plate and Reynolds number (Re) on the flow and heat transfer. The simulations are conducted by using multi-channel computational domain for three different geometries. The code is validated against experimental results and then data for Nusselt number (Nu) and friction factor (f) are presented in a Re range of 100-1500, and intersection angle range of 30-150deg. The simulation confirms the changes of Nuu (averaged over undulated plate) and Nuc (averaged over corrugated plate) with θ representing different characteristics. As θ increases, Nu (Nuu or Nuc) is about 2–16 times higher for the corrugated-undulated configurations CP-UH1 and CP-UP1 and the concomitant f is about 4–100 higher, when compared to a straight channel having square cross section. The minimum of local Nu ( Nuu or Nuc ) is situated at the four contact points where the top plate touches the bottom one, and the high Nu is located upstream of the crest of the conjugate duct. Performance evaluation for the CP-UH1 channel shows that the goodness factors (G) are larger than 1 with the straight channel having a square cross section as a reference, and the 30deg geometry channel has optimal flow area goodness.

Steady three-dimensional flows past hollow fiber membrane arrays – cross flow arrangement

2018 ◽  
Vol 96 (12) ◽  
pp. 1272-1287 ◽  
Author(s):  
Mustafa Usta ◽  
Michael Morabito ◽  
Mohammed Alrehili ◽  
Alaa Hakim ◽  
Alparslan Oztekin
Keyword(s):  
Hollow Fiber ◽  
Hollow Fiber Membrane ◽  
Flow Behavior ◽  
Membrane Surface ◽  
Three Dimensional ◽  
Cross Flow ◽  
Coefficient Of Performance ◽  
Fiber Membrane ◽  
Cfd Simulations ◽  
Flow Configuration

Hollow fiber membrane (HFM) modules are among the most common separation devices employed in membrane separation applications. Three-dimensional steady-state computational fluid dynamics (CFD) simulations are carried out to study flow past hollow fiber membrane banks (HFMB). The current study investigates the effects of flow behavior on membrane performance during binary mixture separations. Carbon dioxide (CO2) removal from methane (CH4) is examined for various arrangements of HFMs in staggered and inline configurations. The common HFM module arrangement is the axial flow configuration. However, this work focuses on the radial cross-flow configuration. The HFM surface is a functional boundary where the suction rate and concentration of each species are coupled and are functions of the local partial pressures, the permeability, and the selectivity of the HFM. CFD simulations employed the turbulent k–ω shear stress transport (SST) model to study HFM performance for Reynolds numbers, 200 ≤ Re ≤ 1000. The efficiency of the inline and staggered arrangements in the separation module is evaluated by the coefficient of performance and the rate of mass flow per unit area of CO2 passing across the membrane surface. This work demonstrates that the module with staggered arrangement outperforms the module with the inline arrangement.

THE INVESTIGATION OF THERMOHYDRODYNAMIC CHARACTERISTIC OF SINGLE AXIAL GROOVE JOURNAL BEARINGS WITH FINITE LENGTH BY USING CFD TECHNIQUES

2013 ◽  
Vol 10 (05) ◽  
pp. 1350031 ◽  
Author(s):  
ALIREZA ARAB SOLGHAR ◽  
S. A. GANDJALIKHAN NASSAB
Keyword(s):  
Stokes Equations ◽  
Control Volume ◽  
Three Dimensional ◽  
Theoretical Data ◽  
Simple Algorithm ◽  
Journal Bearings ◽  
Rate Equations ◽  
Navier Stokes ◽  
Computational Domain ◽  
Oil Flow

The three-dimensional steady state thermohydrodynamic (THD) analysis of an axial grooved oil journal bearing is obtained theoretically. Navier–Stokes equations are solved simultaneously along with turbulent kinetic energy and its dissipation rate equations coupled with the energy equation in the lubricant flow and the heat conduction equation in the bush. The AKN low-Re κ–ε turbulence model is used to simulate the mean turbulent flow field. Considering the complexity of the physical geometry, conformal mapping is used to generate an orthogonal grid and the governing equations are transformed into the computational domain. Discretized forms of the transformed equations are obtained by the control volume method and solved by the SIMPLE algorithm. The numerical results of this analysis can be used to investigate the pressure distribution, volumetric oil flow rate and the loci of shaft in the journal bearings. To validate the computational results, comparison with the experimental and theoretical data of other investigators is made, and reasonable agreement is found.

Three-Dimensional Study of Heat and Mass Transfer in a Partially Porous Elongated Cavity

2010 ◽  
Vol 297-301 ◽  
pp. 728-732
Author(s):  
N. Mimouni ◽  
Salahs Chikh ◽  
Rachid Bennacer
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Cooling System ◽  
Mass Transfer Rate ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Geometrical Parameters ◽  
Computational Domain ◽  
Adsorption Cooling System

A 3D numerical analysis is carried out to investigate heat and mass transfer in a partly porous cavity of high aspect ratio. The goal is to determine the best physical and geometrical parameters that allow optimal heat and mass transfer rate in such domain used in a solar adsorption cooling system. The computational domain consists of a tall cavity heated on the left vertical wall and cooled on the opposing wall. The SIMPLE algorithm is used to handle the velocity pressure coupling. Simulation results allow determining the optimal configuration of the used porous substrate and plain fluid position in the cavity in order to optimize the performance of such solar adsorption cooling installation.

Numerical Simulation and Experiment Research on Pressure Fluctuation and Aerodynamic Noise Field of a Multi-Blade Centrifugal Fan

2012 ◽  
Vol 468-471 ◽  
pp. 2231-2234
Author(s):  
Feng Gao ◽  
Wei Yan Zhong
Keyword(s):  
Numerical Simulation ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Aerodynamic Noise ◽  
Navier Stokes ◽  
Computational Domain ◽  
Centrifugal Fan ◽  
Navier Stokes Equations ◽  
Simulation And Experiment

Numerical simulation of the three-dimensional steady and unsteady turbulent flow in the whole flow field of a multi-blade centrifugal fan is performed. Unstructured grids is used to discrete the computational domain. Pressure boundary conditions are specified to the inlet and the outlet. The SIMPLE algorithm in conjunction with the RNG k-ε turbulent model is used to solve the three-dimensional Navier-Stokes equations. The moving reference frame is adopted to transfer data between the interfaces of the rotating field and the stationary field. Based on the calculation of the inner-flow in the fan, the pressure pulsation of some important monitoring points and the aerodynamic noise distribution, banding together experiment data were farther analyzed The simulation results are of important significance to the optimal design and noise control of the fan.

scholarly journals Thermal analysis and optimization of L-shape fin heat sink under natural convection using ANOVA and Taguchi

2021 ◽  
pp. 317-317
Author(s):  
Numan Habib ◽  
Muftooh Ur Rehman Siddiqi ◽  
Muhammad Tahir
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Heat Sink ◽  
Transfer Rate ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Ambient Air ◽  
Circuit Board ◽  
Computational Domain ◽  
Sink Size

Advancement in electronic systems resulted in miniaturization and high-power densities. Therefore, the rate of heat generation in circuit board increased dramatically. To overcome the problem of overheating, numerous heat sink designs are proposed including L-shape fins heat sink. The thermo-fluidic flow behavior and temperature difference are analyzed to get better understanding of heat transfer from the sink to ambient air. Governing equations for the model of conjugate heat transfer in three-dimensional environment are solved and discretized across the computational domain. Numerous experiments are carried out to validate the numerical results. The effect of fin numbers, height and heat sink size at three different input power is reported. Furthermore, ANOVA and Taguchi statistical methods are used to predict parameters that affect the heat transfer. The study revealed that fin height affects the heat transfer rate the most, and accounts for 25.3 percent increase in heat transfer rate. Optimization of the heat sink is carried out to ensure better efficiency of the proposed HS. The optimized conditions for the sink are observed to be heat sink size of 90mm, 9 number of fins and 33mm of fin height.

3D Simulation on Flow Behavior and Heat Transfer in a Circular Tube with Inclined Different Arrangement of Thin Rib

2012 ◽  
Vol 622-623 ◽  
pp. 628-632
Author(s):  
Amnart Boonloi ◽  
Withada Jedsadaratanachai ◽  
Pongjet Promvonge
Keyword(s):  
Heat Transfer ◽  
Test Section ◽  
Circular Tube ◽  
Flow Behavior ◽  
Central Area ◽  
Simple Algorithm ◽  
Vortex Flows ◽  
Drastic Increase ◽  
Rib Vortex ◽  
Volume Method

This work deals with periodic flow, friction loss and heat transfer characteristics in a constant temperature-surfaced circular tube fitted with rib vortex generators (RVG). The computations are based on the finite volume method with the SIMPLE algorithm implemented. The fluid flow and heat transfer behaviors are presented for Reynolds numbers ranging from 100 to 1000. To generate two main vortex flows through the tested section, the 45o RVGs are mounted repeatedly in in-line arrangements on the top and bottom walls and in the central area of the tested section. Effects of different RVG heights, BR in a range from 0.1D to 0.3D with a single pitch of 1.5D on heat transfer and friction losses in the test section are examined. It is apparent that the vortex flows created by the RVG exist and help to induce periodically impinging flows on a sidewall leading to drastic increase in the heat transfer rate over the test section. The computational results reveal that the optimum thermal performance is about 2.38 for using the RVG height of 0.2D for the RVG placed on the tube walls at the highest Re value.

Numerical Simulation and Experiment Research on Aerodynamic Characteristics of a Multi-Blade Centrifugal Fan

2011 ◽  
Vol 317-319 ◽  
pp. 2157-2161
Author(s):  
Yong Chao Zhang ◽  
Qing Guang Chen ◽  
Yong Jian Zhang ◽  
Xiang Xing Jia
Keyword(s):  
Numerical Simulation ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Internal Flow ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Computational Domain ◽  
Centrifugal Fan ◽  
Cfd Method

The full flow field model of a widely used multi-blade centrifugal fan was built, and unstructured grids were used to discrete the computational domain. The moving reference frame is adopted to transfer data between the interfaces of the rotating field and the stationary field. Pressure boundary conditions are specified to the inlet and the outlet. The SIMPLE algorithm in conjunction with the RNG k-ε turbulent model was used to solve the three-dimensional Navier-Stokes equations. The steady and unsteady numerical simulations of the inner flow in the fan at different working conditions were presented using the CFD method. The numerical simulation results were validated by contrasting to the experiment results. The results displayed the characteristics of the velocity field, pressure field, pressure fluctuation at two monitoring points in the centrifugal fan. The results can provide basis for optimizing the fan design and the internal flow, and have important value of engineering applications in the increase of the overall performance in operation.

scholarly journals Computational Investigation on Fully Developed Periodic Laminar Flow Structure in Baffled Circular Tube with Various BR

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Withada Jedsadaratanachai ◽  
Nuthvipa Jayranaiwachira ◽  
Pongjet Promvonge
Keyword(s):  
Laminar Flow ◽  
Flow Structure ◽  
Circular Tube ◽  
Simple Algorithm ◽  
Reynolds Numbers ◽  
Test Tube ◽  
Periodic Flow ◽  
Flow Profiles ◽  
Pitch Ratio ◽  
Volume Method

This paper presents a 3D numerical analysis of fully developed periodic laminar flow in a circular tube fitted with 45° inclined baffles with inline arrangement. The computations are based on a finite volume method, and the SIMPLE algorithm has been implemented. The characteristics of fluid flow are presented for Reynolds number, Re = 100–1000, based on the hydraulic diameter (D) of the tube. The angled baffles were repeatedly inserted at the middle of the test tube with inline arrangement to generate vortex flows over the tested tube. Effects of different Reynolds numbers and blockage ratios (b/D, BR) with a single pitch ratio of 1 on flow structure in the tested tube were emphasized. The flows in baffled tube show periodic flow atx/D≈2-3, and become a fully developed periodic flow profiles atx/D≈6-7, depending on Re, BR and transverse plane positions. The computational results reveal that the higher of BR and closer position of turbulators, the faster of fully developed periodic flow profiles.

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