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.

Heat Transfer Improvement in a Square Duct with Diagonal Inclined Ribs

2014 ◽  
Vol 931-932 ◽  
pp. 1144-1148
Author(s):  
Supattarachai Suwannapan ◽  
Ratsak Poomsalood ◽  
Pongjet Promvonge ◽  
Withada Jedsadaratanachai ◽  
Thitipat Limkul
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Numerical Study ◽  
Simple Algorithm ◽  
Reynolds Numbers ◽  
Square Duct ◽  
Flow And Heat Transfer ◽  
Pitch Ratio ◽  
Volume Method ◽  
Heat Transfer Improvement

This research presents a numerical study of turbulent periodic flow and heat transfer in threedimensional isothermalfluxed square duct with diagonal inclined rib inserted. The fluid flow and heat transfer characteristics are presented for Reynolds numbers in the range of 4000 to 20,000. The computations based on the finite volume method, and the SIMPLE algorithm has been implemented. Effects of rib pitch ratios (0.5 to 2) at a single blockage ratio of 0.2 and attack angle of 60o on heat transfer and friction factor in the duct are examined and their results of the inclined rib are also compared with those of the smooth duct. It is found that the inclined rib provides higher heat transfer rate and friction factor than the smooth duct for all cases. In addition, the decreasing of the pitch ratio leads to the rise in the Nusselt number and friction factor.

scholarly journals Transition From the Turbulent to the Laminar Regime for Internal Convective Flow With Large Property Variations

1970 ◽  
Vol 92 (3) ◽  
pp. 506-512 ◽  
Author(s):  
C. W. Coon ◽  
H. C. Perkins
Keyword(s):  
Laminar Flow ◽  
Turbulent Flow ◽  
Circular Tube ◽  
Reynolds Numbers ◽  
Bulk Temperature ◽  
Heating Rates ◽  
Nusselt Numbers ◽  
Friction Factors ◽  
High Heating ◽  
Flow Situation

The results of a primarily experimental study of the transition from turbulent flow to laminar flow as a consequence of high heating rates are presented. Results are reported for hydrodynamically fully developed, low Mach number flows of air and helium through a vertical, circular tube. The electrically heated section was 100 diameters in length; entering Reynolds numbers ranged from 1700–40,000, and maximum wall-to-bulk temperature ratios reached 4.4. As a means of predicting the occurrence of a transition from turbulent flow to laminar flow, the experimental results are compared to the acceleration parameter suggested by Moretti and Kays and to a modified form of the parameter that is appropriate to a circular tube. It is suggested that the variable property turbulent flow correlations do not provide acceptable predictions of the Nusselt number and the friction factor if the value 4μq′′G2DTcp≃1.5×10−6 based on bulk properties, is exceeded for an initially turbulent flow situation. It is further suggested that Nusselt numbers and friction factors at locations down-stream from the point xDlaminar≃(2×10−8)(Tinlet)(Reb,inlet)2TwTbmax−1 for bulk temperatures in degrees Rankine may be obtained from the laminar correlation equations even though the flow is initially turbulent.

Fluid Flow and Heat Transfer in an Annulus With Ribs on the Rotating Inner Cylinder Surface

2020 ◽  
Vol 12 (4) ◽  
Author(s):  
S. Gokul ◽  
M. Deepu
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Thermal Performance ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Reynolds Numbers ◽  
Cylinder Surface ◽  
Turbulent Fluid Flow ◽  
Cylindrical Annulus ◽  
Volume Method

Abstract Numerical studies on heat transfer in Taylor-Couette-Poiseuille flow in a cylindrical annulus with ribs mounted on the rotating inner cylinder are presented. The present study focuses on two different types of ribs, namely, longitudinal ribs and helical ribs. Three-dimensional, steady, incompressible, turbulent fluid flow is solved using a semi-implicit method for pressure linked equations (SIMPLE) algorithm based finite volume method. The numerical solution method is validated using two sets of benchmark experimental data. Extensive numerical computations are carried out at various Reynolds numbers (2100 < Re < 2400) and modified Taylor numbers (30,000 < Tam < 90,000) for annulus with and without ribs. Ribs enhance the transport of heat and momentum by inducing more vorticity and turbulence in the flow. The overall performance is presented in terms of thermal performance factor (TPF), which takes in to account the heat transfer as well as pressure drop in the ribbed annulus. Helical ribs are found to offer superior thermal performance than its longitudinal counterpart.

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.

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.

Computation of Velocity Profiles and Pressure Coefficients for a Laminar Flow of Air Over Staggered Array of Tubes

2005 ◽  
Author(s):  
Ramin Rahmani ◽  
Ahad Ramezanpour ◽  
Iraj Mirzaee ◽  
Hassan Shirvani
Keyword(s):  
Laminar Flow ◽  
Stokes Equations ◽  
Tube Bundle ◽  
Pressure Coefficient ◽  
Reynolds Numbers ◽  
Velocity Profiles ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Tube Arrays ◽  
Volume Method

In this study a two dimensional, steady state and incompressible laminar flow for staggered tube arrays in crossflow is investigated numerically. A finite-volume method is used to discretize and solve the governing Navier-Stokes equations for the geometries expressed by a boundary-fitted coordinate system. Solutions for Reynolds numbers of 100, 300, and 500 are obtained for a tube bundle with 10 longitudinal rows. Local velocity profiles on top of each tube and corresponding pressure coefficient are presented at nominal pitch-to-diameter ratios of 1.33, 1.60, and 2.00 for ES, ET, and RS arrangements. Differences in location of separation points are compared for three different arrangements. The predicted results on flow field for pressure coefficient showed a good agreement with available experimental measurements.

Heat transfer enhancement of alumina nanofluid flow in a Circular tube

2018 ◽  
Vol 2 (1) ◽  
Author(s):  
Lanja Refaat ◽  
Adnan Hussein
Keyword(s):  
Heat Transfer ◽  
Circular Tube ◽  
Pure Water ◽  
Simple Algorithm ◽  
Inlet Temperature ◽  
Number Range ◽  
Nanoparticles Concentration ◽  
Alumina Nanofluid ◽  
Volume Method ◽  
The Heat Transfer Coefficient

In this study, the heat transfer coefficient and pressure drop in a circular tube under turbulent flow condition are studied numerically. The Reynolds number range and nanoparticles concentration are in the range of (10000-30000) and 1% to 4% respectively. The governing equations have solved by the finite volume method adopting ANSYS software for simulation. The boundary conditions include: inlet velocity, outlet pressure and constant inlet temperature for hot and cold side and assuming SIMPLE algorithm. The results demonstrate that the AL2O3/Water nanofluid can enhance thermal properties of base fluid to 20% additionally, the heat transfer rate of nanofluid compared to the water is higher but friction factor slightly higher than that of pure water.

scholarly journals Numerical Simulation of Intrachamber Processes in the Power Plant

2021 ◽  
Vol 11 (11) ◽  
pp. 4990
Author(s):  
Boris Benderskiy ◽  
Peter Frankovský ◽  
Alena Chernova
Keyword(s):  
Numerical Simulation ◽  
Power Plant ◽  
Flow Structure ◽  
Power Plants ◽  
Control Volume ◽  
Conjugate Problem ◽  
Topological Features ◽  
Gas Dynamic ◽  
Calculation Results ◽  
Volume Method

This paper considers the issues of numerical modeling of nonstationary spatial gas dynamics in the pre-nozzle volume of the combustion chamber of a power plant with a cylindrical slot channel at the power plant of the mass supply surface. The numerical simulation for spatial objects is based on the solution conjugate problem of heat exchange by the control volume method in the open integrated platform for numerical simulation of continuum mechanics problems (openFoam). The calculation results for gas-dynamic and thermal processes in the power plant with a four-nozzle cover are presented. The analysis of gas-dynamic parameters and thermal flows near the nozzle cover, depending on the canal geometry, is given. The topological features of the flow structure and thermophysical parameters near the nozzle cap were studied. For the first time, the transformation of topological features of the flow structure in the pre-nozzle volume at changes in the mass channel’s geometry is revealed, described, and analyzed. The dependence of the Nusselt number in the central point of stagnation on the time of the power plants operation is revealed.

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