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Modelling of EMC Screens for Radio Base Stations: Part 2: Evaluation of Turbulence Models
KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.ORCID iD: 0000-0001-6139-4400
University of Gävle.
2004 (English)In: Proc. 9th  InterSociety Conf. on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm 2004), Las Vegas, NV, USA, IEEE Press, 2004, 471-478 p.Conference paper, Published paper (Refereed)
Abstract [en]

The objective of this paper is to investigate the performance of five well-known turbulence models and 2 wall treatments, in order to predict the details of the flow patterns through an EMC (ElectroMagnetic Compatibility) screen. The employed turbulence models are investigated in the present study is four different eddy-viscosity models; the standard k-ε model, the renormalization group (RNG) k-ε model, the realizable k-ε model and the k-ω model, as well as the Reynolds stress model, RSM. The commercial finite volume code Fluent 6.1 was used for simulation.

A steady-state three-dimensional model, which serves as the most accurate representation of the model, was used in order to predict the details of the air flow paths and pressure field. The flow was assumed to be isothermal, turbulent and incompressible.

The numerical predictions were validated experimentally by using wind tunnel measurements and smoke visualization. The performances of the turbulence models are discussed and the RSM results are compared with other two-equation turbulence models. The result shows that choosing the right turbulence model and wall treatment does not have a great influence on the prediction of pressure drop and the velocity field. The pressure field is over predicted about 15% and the velocity average deviation at several locations before and after the screen is less than 10%. Simulations using a hydraulic impedance surface, i.e. without a detail modeling of the EMC screen, show that the pressure field is also over predicted and great differences are observed in the velocity field.

Place, publisher, year, edition, pages
IEEE Press, 2004. 471-478 p.
Keyword [en]
RNG, RSM, k-ε, k-ω, pressure drop, perforated plate, porosity, EMC screen, subrack, velocity profile, flow pattern, hydraulic impedance
National Category
Energy Engineering
Identifiers
URN: urn:nbn:se:kth:diva-63407Scopus ID: 2-s2.0-4444325242ISBN: 0-7803-8357-5 (print)OAI: oai:DiVA.org:kth-63407DiVA: diva2:482183
Conference
9th InterSociety Conf. on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm 2004), Las Vegas, NV, USA
Note
QC 20120131Available from: 2012-01-23 Created: 2012-01-23 Last updated: 2012-01-31Bibliographically approved
In thesis
1. Experimental and numerical study of the thermal and hydraulic effect of EMC screens in radio base stations: detailed and compact models
Open this publication in new window or tab >>Experimental and numerical study of the thermal and hydraulic effect of EMC screens in radio base stations: detailed and compact models
2006 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Today’s telecommunication cabinets use Electro Magnetic Compliance (EMC) screens in order to reduce electromagnetic noise that can cause some miss functions in electronic equipment.

Many radio base stations (RBSs) use a 90-degree building architecture: the flow inlet is perpendicular to the EMC screen, which creates a complex flow, with a 90-degree air turn, expansions, compressions, perforated plates and PCBs. It is of great interest to study how the EMC screen interacts with the rest of components and analyze the total pressure drop and how much the flow pattern changes due to the placement of the screen.

Velocity, pressure and temperature measurements as well as flow pattern visualizations have been carried out to gain good insight into the flow and heat transfer characteristics in a subrack model of an RBS. Furthermore, these measurements have been very useful for validating detailed CFD models and evaluating several turbulence models.

Nowadays, industrial competition has caused a substantial decrease in the time-to-market of products. This fact makes the use of compact models in the first stages of the design process of vital importance. Accurate and fast compact models can to a great extent decrease the time for design, and thus for production.

Hence, to determine the correlations between the pressure drop and flow pattern on the PCBs as a function of the geometry and the Reynolds number, based on a detailed CFD parametric study, was one objective. Furthermore, the development of a compact model using a porous media approach (using two directional-loss coefficients) has been accomplished. Two correlations of these directional loss coefficients were found as a function of the geometry and Reynolds number.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006
Series
Trita-REFR, ISSN 1102-0245 ; 06/57
Keyword
sub-rack, perforated plate, air cooling, 90 degrees turn, flow deistribution, CFD, measurement
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-4265 (URN)978-91-7178-553-4 (ISBN)
Public defence
2007-01-29, Salongen, KTHB, Osquars Backe 31, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20100630Available from: 2007-01-11 Created: 2007-01-11 Last updated: 2012-03-23Bibliographically approved

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