scholarly journals Numerical Study of Cooling by Ferrofluids in an Electrical Transformer using an Axisymmetric Model

2021 ◽  
pp. 1-1
Author(s):  
Raphael Zanella ◽  
Caroline Nore ◽  
Xavier Mininger ◽  
Frederic Bouillault ◽  
Jean-Luc Guermond
Keyword(s):  
Numerical Study ◽  
Axisymmetric Model

Mixed Experimental and Numerical Study of Steel Ferrule Forming by Low-Contact Deformation Process

2012 ◽  
Author(s):  
J. Raujol-Veillé ◽  
F. Toussaint ◽  
L. Tabourot ◽  
M. Vautrot ◽  
P. Balland
Keyword(s):  
Numerical Analysis ◽  
Finite Elements ◽  
Deformation Process ◽  
3D Model ◽  
Numerical Study ◽  
Numerical Comparison ◽  
Contact Deformation ◽  
Axisymmetric Model ◽  
Part Geometry ◽  
Cpu Time

The present work aims to develop a steel ferrule forming by a low-contact deformation process using numerical analysis. Two Finite Elements (FE) models have been developed within ABAQUS. The first one is a 3D model that can both calculate the forming geometry of the part and the forces applied on the roller. The second one is a 2D axisymmetric model allowing reducing the CPU time without important loss of accuracy on the final part geometry. We present in this paper a mixed experimental/numerical comparison performed with each model and discuss the results with measurements coming from a part manufacturing by the industrial partner.

Thermocapillary migration and interaction of drops: two non-merging drops in an aligned arrangement

2015 ◽  
Vol 766 ◽  
pp. 436-467 ◽  
Author(s):  
Zhaohua Yin ◽  
Qiaohong Li
Keyword(s):  
Capillary Number ◽  
Marangoni Number ◽  
Numerical Study ◽  
Drop Deformation ◽  
Initial Distance ◽  
Axisymmetric Model ◽  
Thermocapillary Migration

AbstractA numerical study on the interaction of two spherical drops in thermocapillary migration in microgravity is presented. Unequal drop sizes in the axisymmetric model lead to strong drop interaction if the leading drop is smaller. The effect of the ratio of the two drop radii, their initial distance apart, and non-dimensional numbers on the interaction is studied in the case of non-merging drops in detail. The Marangoni number adopted in this paper is fairly large (around 100) so as to reveal the phenomena of real flows. As a result, the heat wake behind the leading drop plays an important role in drop interaction, and obviously different final drop distances and transient migration processes are observed for various sets of non-dimensional numbers. The influence of drop deformation on drop interaction is also investigated for relatively large capillary number (up to 0.2). Finally, some simulations are performed to explain the phenomena of drop interaction in previous experiments, and some suggestions for future experiments are also provided.

Investigation of the Relation Between Tube Spacing and Tube Sheet Deformation in Heat Exchangers due to the Mechanical Rolling Process: A Numerical Study

2015 ◽  
Author(s):  
Søren Bøgelund Madsen ◽  
Claus Hessler Ibsen ◽  
Bo Gervang ◽  
Anders Schmidt Kristensen
Keyword(s):  
Thermal Performance ◽  
Heat Exchangers ◽  
Numerical Study ◽  
Tube Sheet ◽  
Expansion Process ◽  
Cold Forming ◽  
Axisymmetric Model ◽  
Finned Tubes ◽  
Small Tube ◽  
Sheet Deformation

The focus of this paper is a numerical investigation of tubesheet deformation in tube-tubesheet joints used in tube bank heat exchangers. To increase the thermal performance of a cooler the tubes can be moved closer together to increase turbulence and the heat transfer coefficient. Reducing the tube spacing is an alternative to using finned tubes to increase thermal performance. Finned tubes is more susceptible to fouling and therefore the small tube spacing can be an attractive alternative in some cases. From a manufacturing point of view, there are some problems with small tube spacing. When the tube spacing is reduced the deformation of the tube sheet increases. The relation between the tube spacing and tubesheet deformation is of great interest to the thermal designers of heat exchangers since it sets a limit for the tube spacing. The limit depends on how much tube sheet deformation is acceptable in the design. In most cases, the tubes are joined to the tube sheet by an expansive cold forming process. The expansion process that is investigated in this paper is the mechanical rolling expansion process. The tube is plastically deformed by a series of hardened steel rollers that roll across the inner tube surface while being pushed outwards. This results in a residual contact pressure between the tube and tube sheet after relaxation/springback. The expansion process is modeled using finite elements, the model used is a 2D plane-strain model that is capable of capturing the effect of adjacent holes. This approach is new compared to previous research done in the field of mechanical roll expansion where the most commonly used model is an axisymmetric model. It is however not possible to investigate tube sheet deformation versus tube spacing with the axisymmetric model since it doesn’t include the effect of adjacent holes. The material used in the analysis is a typical stainless steel, the material is modeled using a bilinear isotropic hardening model. At some point, the deformation of the tube sheet will exponentially increase with reduced tube spacing. This effect can only be investigated using numerical tools. Too much tube sheet deformation is not desirable since it will cause the tube sheet to permanently change shape and in some cases, adjacent tube-tubesheet joints will be compromised due to the nearby expansion. The results of this paper is the relation between the tube spacing and the amount of tubesheet deformation for a given amount of apparent tube wall reduction. This relation is used to set up limits for the amount of expansion and the minimum tube spacing for the given material combination.

Numerical Study on a Drop-on-Demand Micro Droplet Print Head

2012 ◽  
Vol 217-219 ◽  
pp. 1429-1434
Author(s):  
Cheng Jian Zheng ◽  
Sheng Dong Gao ◽  
Ying Xue Yao
Keyword(s):  
Conceptual Design ◽  
Piezoelectric Actuator ◽  
Numerical Study ◽  
Metal Droplet ◽  
Axisymmetric Model ◽  
Print Head ◽  
On Demand ◽  
Drop On Demand ◽  
Vof Model ◽  
Parametric Studies

A conceptual design of a drop-on-demand(DOD) micro metal droplet print head, which is characterized as the non-heat affection of piezoelectric actuator and a desirable controllability on droplet condition, is devised. With a 2D axisymmetric model and a VOF model, the droplet evolution is simulated for understanding the mechanism within. Parametric studies are followed to investigate relationship between droplet condition and print head parameters for realizing accurate control of droplet condition.

Numerical study of the low-frequency atomic dynamics in a Lennard-Jones glass

1998 ◽  
Vol 77 (2) ◽  
pp. 473-484 ◽  
Author(s):  
M. Sampoli, P. Benassi, R. Dell'Anna,
Keyword(s):  
Numerical Study ◽  
Low Frequency ◽  
Lennard Jones

Numerical simulation of the tree higro-thermal response in forest fire environment

2020 ◽  
pp. 57-65
Author(s):  
Eusébio Conceiçã ◽  
João Gomes ◽  
Maria Manuela Lúcio ◽  
Jorge Raposo ◽  
Domingos Xavier Viegas ◽  
...  
Keyword(s):  
Forest Fire ◽  
Numerical Study ◽  
Thermal Response ◽  
View Factor ◽  
Tree Model ◽  
Pine Tree ◽  
Surface Temperatures ◽  
Fire Environment ◽  
Fire Front ◽  
Heat Exchanges

This paper refers to a numerical study of the hypo-thermal behaviour of a pine tree in a forest fire environment. The pine tree thermal response numerical model is based on energy balance integral equations for the tree elements and mass balance integral equation for the water in the tree. The simulation performed considers the heat conduction through the tree elements, heat exchanges by convection between the external tree surfaces and the environment, heat exchanges by radiation between the flame and the external tree surfaces and water heat loss by evaporation from the tree to the environment. The virtual three-dimensional tree model has a height of 7.5 m and is constituted by 8863 cylindrical elements representative of its trunks, branches and leaves. The fire front has 10 m long and a 2 m high. The study was conducted taking into account that the pine tree is located 5, 10 or 15 m from the fire front. For these three analyzed distances, the numerical results obtained regarding to the distribution of the view factors, mean radiant temperature and surface temperatures of the pine tree are presented. As main conclusion, it can be stated that the values of the view factor, MRT and surface temperatures of the pine tree decrease with increasing distance from the pine tree in front of fire.

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