scholarly journals Flow and Heat Transfer Characteristic of Inclined Oval Trench Dimples With Numerical Simulation

CFD letters ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 61-71
Author(s):  
Ibroheng piya ◽  
Pathomporn Narato ◽  
Makatar Wae-hayee ◽  
Chayut Nuntadusit
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamic ◽  
Pressure Coefficient ◽  
Transfer Characteristic ◽  
Longitudinal Vortex ◽  
Bottom Surface ◽  
Ansys Fluent ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer ◽  
Inclined Angle

In this work, flow and heat transfer in a channel having oval trench dimples were investigated numerically. 3-D channel flow with a cross-section of 300-mm width and 32-mm height were created using Computational Fluid Dynamic (CFD) with ANSYS, Fluent (V.15.0). Five oval trench dimples with 3-mm depth, 10.0-mm width and 45-mm length arranging with a single row and in-line configuration were located on the bottom surface of the channel. Reynolds number based on hydraulic diameter of the channel were fixed at Re=20,000 whereas a dimple inclined angle defined as the angle of dimple centreline to the mainstream was varied at 0, 15, 30 and 45 degrees. SST turbulent model was used to solve governing Equations. The result show that longitudinal vortex flow occurred at ?=15° to 45° which would be enhance heat transfer on the surface. When inclined angle became larger, the areas of Nusselt number and high total pressure coefficient took place at dimple edge in +Z direction. The peak of average spanwise Nusselt numbers took place for the case of ?=45°. Moreover, the area of high spanwise average Nusselt numbers (>100) for the case ?=30° was the largest.

Effect of Fin Inclination Angel on Heat Transfer Improvement in an Annular Space of a Rotor Stator

2021 ◽  
Vol 409 ◽  
pp. 110-122
Author(s):  
Youcef Attou ◽  
Farouk Kebir
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Outer Cylinder ◽  
Convection Flow ◽  
Ansys Fluent ◽  
Annular Channels ◽  
Flow And Heat Transfer ◽  
Inclined Angle ◽  
The Impact ◽  
Heat Transfer Improvement

The present work deals with the numerical investigation of forced convection flow and heat transfer in a finned concentric annulus. The outer cylinder is axially finned while the rotating inner cylinder has a smooth surface. Our research focus on the impact of the fin inclination angle on heat transfer enhancement in rotating annular channels. Tests were carried out for different geometrical configurations using fins with inclined angle (α = 30°, 60°, 90° and 120°). Numerical study is based on effective Reynolds number and Taylor number. The results obtained using the code ANSYS-Fluent with SST k-ω turbulence model show a good agreement between the experimental and the numerical results. In the presence of rotational flow (Ta = 1.14 × 106), the results indicate that α =120° is the optimal case which improves significantly the heat and mass transfer inside the finned channel.

A Numerical Study of Heat Transfer and Flow Structure in Channels With Miniature V Rib-Dimple Hybrid Structure on One Wall

2018 ◽  
Author(s):  
Peng Zhang ◽  
Yu Rao ◽  
Yanlin Li
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Numerical Simulations ◽  
Numerical Study ◽  
Reynolds Numbers ◽  
Hybrid Structure ◽  
Transfer Enhancement ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer ◽  
Flow Mixing

This paper presents a numerical study on turbulent flow and heat transfer in the channels with a novel hybrid cooling structure with miniature V-shaped ribs and dimples on one wall. The heat transfer characteristics, pressure loss and turbulent flow structures in the channels with the rib-dimples with three different rib heights of 0.6 mm, 1.0 mm and 1.5 mm are obtained for the Reynolds numbers ranging from 18,700 to 60,000 by numerical simulations, which are also compared with counterpart of a pure dimpled and pure V ribbed channel. The results show that the overall Nusselt numbers of the V rib-dimple channel with the rib height of 1.5 mm is up to 70% higher than that of the channels with pure dimples. The numerical simulations show that the arrangement of the miniature V rib upstream each dimple induces complex secondary flow near the wall and generates downwashing vortices, which intensifies the flow mixing and turbulent kinetic energy in the dimple, resulting in significant improvement in heat transfer enhancement and uniformness.

scholarly journals Nusselt number evaluation for combined radiative and convective heat transfer in flow of gaseous products from combustion

2013 ◽  
Vol 17 (4) ◽  
pp. 1093-1106 ◽  
Author(s):  
Soraya Trabelsi ◽  
Wissem Lakhal ◽  
Ezeddine Sediki ◽  
Mahmoud Moussa
Keyword(s):  
Heat Transfer ◽  
Radiation Effects ◽  
Combustion Products ◽  
Radiative Properties ◽  
Inlet Temperature ◽  
Gaseous Products ◽  
Nusselt Numbers ◽  
Coupled Heat Transfer ◽  
Flow And Heat Transfer ◽  
Fluid Properties

Combined convection and radiation in simultaneously developing laminar flow and heat transfer is numerically considered with a discrete-direction method. Coupled heat transfer in absorbing emitting but not scattering gases is presented in some cases of practical situations such as combustion of natural gas, propane and heavy fuel. Numerical calculations are performed to evaluate the thermal radiation effects on heat transfer through combustion products flowing inside circular ducts. The radiative properties of the flowing gases are modeled by using the absorption distribution function (ADF) model. The fluid is a mixture of carbon dioxide, water vapor, and nitrogen. The flow and energy balance equations are solved simultaneously with temperature dependent fluid properties. The bulk mean temperature variations and Nusselt numbers are shown for a uniform inlet temperature. Total, radiative and convective mean Nusselt numbers and their axial evolution for different gas mixtures produced by combustion with oxygen are explored.

scholarly journals Effect of Rayleigh Number on Internal Eccentricity in a Heated Horizontal Elliptical Cylinder to its Coaxial Square Enclosure

2020 ◽  
Vol 25 (3) ◽  
pp. 17-29
Author(s):  
Abdelkrim Bouras ◽  
Djedid Taloub ◽  
Zied Driss
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Outer Cylinder ◽  
Boussinesq Approximation ◽  
Square Enclosure ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer ◽  
Commercial Code ◽  
Volume Method ◽  
Rayleigh Numbers

AbstractThis paper deals with numerical investigation of a natural convective flow in a horizontal annular space between a heated square inner cylinder and a cold elliptical outer cylinder with a Newtonian fluid. Uniform temperatures are imposed along walls of the enclosure. The governing equations of the problem were solved numerically by the commercial code Fluent, based on the finite volume method and the Boussinesq approximation. The effects of Geometry Ratio GR and Rayleigh numbers on fluid flow and heat transfer performance are investigated. The Rayleigh number is varied from 103 to 106. Throughout the study the relevant results are presented in terms of isotherms, and streamlines. From the results, we found that the increase in the Geometry Ratio B leads to an increase of the heat transfer coefficient. The heat transfer rate in the annulus is translated in terms of the average Nusselt numbers along the enclosure’s sides. Tecplot 7 program was used to plot the curves which cleared these relations and isotherms and streamlines which illustrate the behavior of air through the channel and its variation with other parameters. The results for the streamlines, isotherms, local and average Nusselt numbers average Nusselt numbers are compared with previous works and show good agreement.

Numerical simulation of wind loads on solar panels

2018 ◽  
Vol 32 (12n13) ◽  
pp. 1840009 ◽  
Author(s):  
Kao-Chun Su ◽  
Kung-Ming Chung ◽  
Shu-Tsung Hsu
Keyword(s):  
Fluid Dynamic ◽  
Pressure Coefficient ◽  
Solar Panel ◽  
Wind Loads ◽  
Strong Wind ◽  
Solar Panels ◽  
Wind Uplift ◽  
Aspect Ratios ◽  
Wind Tunnel Data ◽  
Inclined Angle

Solar panels mounted on the roof of a building or ground are often vulnerable to strong wind loads. This study aims to investigate wind loads on solar panels using computational fluid dynamic (CFD). The results show good agreement with wind tunnel data, e.g. the streamwise distribution of mean surface pressure coefficient of a solar panel. Wind uplift for solar panels with four aspect ratios is evaluated. The effect of inclined angle and clearance (or height) of a solar panel is addressed. It is found that wind uplift of a solar panel increases when there is an increase in inclined angle and the clearance above ground shows an opposite effect.

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