Comparing 2D and 3D numerical simulation results of gas flow velocity in convection reflow oven

2014 ◽  
Vol 26 (4) ◽  
pp. 223-230 ◽  
Author(s):  
Balázs Illés
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Flow Velocity ◽  
Gas Flow ◽  
Content Type ◽  
Simulation Results ◽  
2D And 3D ◽  
Gas Flow Velocity ◽  
2D Model ◽  
Gas Flow Field

Purpose – This paper aims to compare and study two-dimensional (2D) and three-dimensional (3D) computational fluid dynamics simulation results of gas flow velocity in a convection reflow oven and show the differences of the different modeling aspects. With the spread of finer surface-mounted devices, it is important to understand convection reflow soldering technology more deeply. Design/methodology/approach – Convection reflow ovens are divided into zones. Every zone contains an upper and a lower nozzle-matrix. The gas flow velocity field is one of the most important parameters of the local heat transfer in the oven. It is not possible to examine the gas flow field with classical experimental methods due to the extreme circumstances in the reflow oven. Therefore, numerical simulations are necessary. Findings – The heat transfer changes highly along the moving direction of the assembly, and it is nearly homogeneous along the traverse direction of the zones. The gas flow velocity values of the 2D model are too high due to the geometrical distortions of the 2D model. On the other hand, the calculated flow field of the 2D model is more accurate than in the 3D model due to the finer mesh. Research limitations/implications – Investigating the effects of tall components on a printed wiring board inside the gas flow field and further analysis of the mesh size effect on the models. Practical implications – The presented results can be useful during the design of a simulation study in a reflow oven (or in similar processes). Originality/value – The presented results provide a completely novel approach from the aspect of 2D and 3D simulations of a convection reflow oven. The results also reveal the heat transfer differences.

Unsteady and porous media flow of reactive non-Newtonian fluids subjected to buoyancy and suction/injection

2015 ◽  
Vol 25 (7) ◽  
pp. 1682-1704 ◽  
Author(s):  
Tirivanhu Chinyoka ◽  
Daniel Oluwole Makinde
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Boundary Conditions ◽  
Flow Velocity ◽  
Flow System ◽  
Finite Difference Methods ◽  
Porous Media Flow ◽  
Convective Boundary Conditions ◽  
Convective Boundary ◽  
Content Type

Purpose – The purpose of this paper is to examine the unsteady pressure-driven flow of a reactive third-grade non-Newtonian fluid in a channel filled with a porous medium. The flow is subjected to buoyancy, suction/injection asymmetrical and convective boundary conditions. Design/methodology/approach – The authors assume that exothermic chemical reactions take place within the flow system and that the asymmetric convective heat exchange with the ambient at the surfaces follow Newton’s law of cooling. The authors also assume unidirectional suction injection flow of uniform strength across the channel. The flow system is modeled via coupled non-linear partial differential equations derived from conservation laws of physics. The flow velocity and temperature are obtained by solving the governing equations numerically using semi-implicit finite difference methods. Findings – The authors present the results graphically and draw qualitative and quantitative observations and conclusions with respect to various parameters embedded in the problem. In particular the authors make observations regarding the effects of bouyancy, convective boundary conditions, suction/injection, non-Newtonian character and reaction strength on the flow velocity, temperature, wall shear stress and wall heat transfer. Originality/value – The combined fluid dynamical, porous media and heat transfer effects investigated in this paper have to the authors’ knowledge not been studied. Such fluid dynamical problems find important application in petroleum recovery.

Numerical Analysis of Flow Fields and Temperature Fields in a Regenerative Heating Furnace for Steel Pipes

2018 ◽  
Vol 10 (3) ◽  
Author(s):  
Yi Han ◽  
Feng Liu ◽  
Xin Ran
Keyword(s):  
Temperature Field ◽  
Flow Field ◽  
Flow Velocity ◽  
Gas Flow ◽  
Flow Fields ◽  
Heating Furnace ◽  
Temperature Fields ◽  
Turbulent Layer ◽  
Steel Pipes ◽  
Pipe Blanks

In the production process of large-diameter seamless steel pipes, the blank heating quality before roll piercing has an important effect on whether subsequently conforming piping is produced. Obtaining accurate pipe blank heating temperature fields is the basis for establishing and optimizing a seamless pipe heating schedule. In this paper, the thermal process in a regenerative heating furnace was studied using fluent software, and the distribution laws of the flow field in the furnace and of the temperature field around the pipe blanks were obtained and verified experimentally. The heating furnace for pipe blanks was analyzed from multiple perspectives, including overall flow field, flow fields at different cross sections, and overall temperature field. It was found that the changeover process of the regenerative heating furnace caused the temperature in the upper part of the furnace to fluctuate. Under the pipe blanks, the gas flow was relatively thin, and the flow velocity was relatively low, facilitating the formation of a viscous turbulent layer and thereby inhibiting heat exchange around the pipe blanks. The mutual interference between the gas flow from burners and the return gas from the furnace tail flue led to different flow velocity directions at different positions, and such interference was relatively evident in the middle part of the furnace. A temperature “layering” phenomenon occurred between the upper and lower parts of the pipe blanks. The study in this paper has some significant usefulness for in-depth exploration of the characteristics of regenerative heating furnaces for steel pipes.

The Features of Measuring the Gas Flow Velocity in Pipes by an Ultrasonic Correlation Method

2021 ◽  
Vol 67 (2) ◽  
pp. 216-221
Author(s):  
A. D. Mansfeld ◽  
G. P. Volkov ◽  
R. V. Belyaev ◽  
A. G. Sanin ◽  
P. R. Gromov ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Gas Flow ◽  
Correlation Method ◽  
Gas Flow Velocity

scholarly journals METHODS OF MAINTAINING THE PROJECT LEVELS OF GAS PRODUCTION AT THE FINAL STAGE OF DEVELOPMENT OF DEPOSITS

2017 ◽  
pp. 80-83
Author(s):  
E. V. Panikarovskii ◽  
V. V. Panikarovskii
Keyword(s):  
Flow Velocity ◽  
Final Stage ◽  
Gas Flow ◽  
Gas Production ◽  
Stage Of Development ◽  
Surfactant Solutions ◽  
Gas Flow Velocity

In the case of self-kill of wells, the gas flow velocity in the lifting column is not sufficient for carrying to the surface of the liquid, accumulated in the wellbore. To remove liquid from the bottom of wells, solid and liquid surfactants are used. As a result of conducted studies of surfactant compositions, the components of surfactant solutions were chosen to remove liquid from the bottom of wells.

Magnetohydrodynamic effects on flow structures and heat transfer over two cylinders wrapped with a porous layer in side

2016 ◽  
Vol 26 (5) ◽  
pp. 1416-1432 ◽  
Author(s):  
Saman Rashidi ◽  
Javad Abolfazli Esfahani ◽  
Mohammad Sadegh Valipour ◽  
Masoud Bovand ◽  
Ioan Pop
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Flow Field ◽  
Porous Layer ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Circular Cylinders ◽  
Flow Structures ◽  
Content Type ◽  
The Magnetic Field

Purpose – The analysis of the flow field and heat transfer around a tube row or tube banks wrapped with porous layer have many related engineering applications. Examples include the reactor safety analysis, combustion, compact heat exchangers, solar power collectors, high-performance insulation for buildings and many another applications. The purpose of this paper is to perform a numerical study on flows passing through two circular cylinders in side-by-side arrangement wrapped with a porous layer under the influence of a magnetic field. The authors focus the attention to the effects of magnetic field, Darcy number and pitch ratio on the mechanism of convection heat transfer and flow structures. Design/methodology/approach – The Darcy-Brinkman-Forchheimer model for simulating the flow in porous medium along with the Maxwell equations for providing the coupling between the flow field and the magnetic field have been used. Equations with the relevant boundary conditions are numerically solved using a finite volume approach. In this study, Stuart and Darcy numbers are varied within the range of 0 < N < 3 and 1e-6 < Da < 1e-2, respectively, and Reynolds and Prandtl numbers are equal to Re=100 and Pr=0.71, respectively. Findings – The results show that the drag coefficient decreases for N < 0.6 and increases for N > 0.6. Also, the effect of magnetic field is negligible in the gap between two cylinders because the magnetic field for two cylinders counteracts each other in these regions. Originality/value – To the authors knowledge, in the open literature, flow passing over two circular cylinders in side-by-side arrangement wrapped with a porous layer has been rarely investigated especially under the influence of a magnetic field.

Effects of Shield Gas Flow on Meltpool Variability and Signature in Scanned Laser Melting

2020 ◽  
Author(s):  
David C. Deisenroth ◽  
Jorge Neira ◽  
Jordan Weaver ◽  
Ho Yeung
Keyword(s):  
Additive Manufacturing ◽  
Aspect Ratio ◽  
Flow Velocity ◽  
Process Monitoring ◽  
Gas Flow ◽  
Laser Energy ◽  
Flow Speed ◽  
Powder Bed ◽  
Flow Speeds ◽  
Gas Flow Velocity

Abstract In laser powder bed fusion metal additive manufacturing, insufficient shield gas flow allows accumulation of condensate and ejecta above the build plane and in the beam path. These process byproducts are associated with beam obstruction, attenuation, and thermal lensing, which then lead to lack of fusion and other defects. Furthermore, lack of gas flow can allow excessive amounts of ejecta to redeposit onto the build surface or powder bed, causing further part defects. The current investigation was a preliminary study on how gas flow velocity and direction affect laser delivery to a bare substrate of Nickel Alloy 625 (IN625) in the National Institute of Standards and Technology (NIST) Additive Manufacturing Metrology Testbed (AMMT). Melt tracks were formed under several gas flow speeds, gas flow directions, and energy densities. The tracks were then cross-sectioned and measured. The melt track aspect ratio and aspect ratio coefficient of variation (CV) were reported as a function of gas flow speed and direction. It was found that a mean gas flow velocity of 6.7 m/s from a nozzle 6.35 mm in diameter was sufficient to reduce meltpool aspect ratio CV to less than 15 %. Real-time inline hotspot area and its CV were evaluated as a process monitoring signature for identifying poor laser delivery due to inadequate gas flow. It was found that inline hotspot size could be used to distinguish between conduction mode and transition mode processes, but became diminishingly sensitive as applied laser energy density increased toward keyhole mode. Increased hotspot size CV (associated with inadequate gas flow) was associated with an increased meltpool aspect ratio CV. Finally, it was found that use of the inline hotspot CV showed a bias toward higher CV values when the laser was scanned nominally toward the gas flow, which indicates that this bias must be considered in order to use hotspot area CV as a process monitoring signature. This study concludes that gas flow speed and direction have important ramifications for both laser delivery and process monitoring.

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