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Large-eddy simulation of an impinging jet in a cross-flow on a heated wall-mounted cube
Linköping University, Department of Management and Engineering. Linköping University, The Institute of Technology. Division of Energy and Mechanical Engineering, Department of Technology and Built Environment, University of Gävle, Gävle, Sweden.
Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology. Division of Energy and Mechanical Engineering, Department of Technology and Built Environment, University of Gävle, Gävle, Sweden.
2009 (English)In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, Vol. 52, no 3-4, 921-931 p.Article in journal (Refereed) Published
Abstract [en]

A large-eddy simulation (LES) is performed in order to predict the mean velocity field, the turbulence characteristics and the heat transfer rate of an impinging jet in cross-flow configuration on a heated wall-mounted cube. The WALE model was used to model the subgrid-scale tensor. The results from the LES are compared with a Reynolds stress model (RSM) and against earlier measurements with identical set-up. A comparison between the results from the predictions and the measurements shows that in general the LES has better agreement with the measurements compared to the RSM and particularly in the stagnation region of the impinging jet.

Place, publisher, year, edition, pages
Elsevier, 2009. Vol. 52, no 3-4, 921-931 p.
Keyword [en]
Large-eddy simulation, Impinging jet in a cross-now, Reynolds stress model, Electronic cooling
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-16620DOI: 10.1016/j.ijheatmasstransfer.2008.03.035ISI: 000262556200043OAI: oai:DiVA.org:liu-16620DiVA: diva2:159527
Available from: 2009-02-07 Created: 2009-02-06 Last updated: 2014-03-18Bibliographically approved
In thesis
1. Numerical investigation of the turbulent flow and heat transfer around a heated cube cooled by and impinging jet in a cross-flow
Open this publication in new window or tab >>Numerical investigation of the turbulent flow and heat transfer around a heated cube cooled by and impinging jet in a cross-flow
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Impinging jets are used for many industrial applications where high heat and mass transfer rates are required. The electronic industry is one of the fastest growing industries and applications of cooling technology in this field are of considerable importance. Forced channel flow is frequently used as a cooling technique. In combating the whole thermal load with forced channel flow, excessive flow rates will be required. The typical electronic system contains one or a few high heat–dissipating components. One possible method to face this problem is to divide the channel flow into an impinging jet and a low-velocity cross-flow. The impinging jet is placed over the high heat-dissipating component and provides a local region with high cooling performance, especially at the stagnation point. The cross-flow is important to insure that well-distributed cooling performance is provided at the remaining part of the electronic system, which requires less cooling.

Impinging jets are also of great scientific interest. Extensive experimental and numerical research has been carried out to predict the flow and heat transfer characteristics in the stagnation region of an impinging jet where most of the investigations have been focused on axi–symmetric round impinging jets without any cross-flow.

The purpose of this study is to examine a spot cooling technique consisting of en impinging jet in combination with a low-velocity cross-flow by use of CFD. The cases are limited to a heated wall-mounted cube with different height which is placed in a channel with different heights and cooled by an impinging jet and a cross-flow with different velocities. The study can be divided into three parts: a verification study, a detailed study and a parametric study.

The verification part consists of a verification of two steady-state Reynolds-Averaged Navier-Stokes turbulence models, a v2-f model and a Reynolds Stress Model (RSM). The results show that both models predicted similar results in the near-wall region except in the stagnation region from the impinging jet where the wall-normal turbulent Reynolds stresses and the turbulent kinetic energy where significantly higher in the RSM than in the v2-f model and in the measurements. The general trend was that the predicted surface temperature and the mean velocity field in the free shear-flow, i.e. far from the walls, from the RSM was in better agreement with the measurements than the results from the v2-f model.

The detailed study presents an unsteady simulation by use of Large Eddy Simulation (LES) for a case identical to the verification study in order to predict the time-averaged velocity field, the turbulence characteristics and the heat transfer rate. The agreements between the results from the LES and the measurements were in general improved compared with the RSM and the v2-f model especially in the stagnation region from the impinging jet.

The parametric study is carried out by use of the validated RSM where influence of the velocities of the impinging jet and the cross-flow, the distance between the top and bottom plates, and the height of the cube on the heat transfer rate and on the pressure drops was investigated.

Place, publisher, year, edition, pages
Linköping: LiU-tryck, 2009. 84 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1227
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-52265 (URN)978-91-7393-740-5 (ISBN)
Public defence
2008-12-12, C3, Hus C, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2009-12-14 Created: 2009-12-14 Last updated: 2012-11-14Bibliographically approved

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