PRESENTATION OF CFD ACTIVITIES IN CV GROUP

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PRESENTATION OF CFD ACTIVITIES IN CV GROUP
Daniel Gasser
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What is CFD (1)?

• CFD (Computational Fluid Dynamic) is a mean to
  simulate on computer a large range of phenomena
  linked to fluid mechanic
• flow analysis
• heat transfer problems
• thermodynamic
• ...

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What is CFD (2)?

• Numerical resolution of equations governing fluid
  dynamic (conservation of mass, momentum and
  energy)
• The main data required for a CFD analysis are
• boundary and initial conditions
• a mesh where physical values are calculated
  (velocity, pressure, temperature ...)

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Goals of CFD studies in CV group

• Get useful information about phenomena occurring
  in cooling and ventilation facilities (flow
  paths, head losses, heat transfer efficiency
  ...).
• Help in facilities design pipe dimensioning,
  choice of a cooling fluid, shape improvement ...

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Current studies in CV group

• Study of the bus bars cooling for ATLAS
  experiment.
• Thermal analysis of an electronic box in the ECAL
  sub-detector (CMS experiment).
• Cooling analysis of the ALICE experiment detector.

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Cooling of the bus bar for ATLAS (context)

• Compare the efficiency of air natural convection
  cooling with water cooling.
• Choice of a simple cooling system.

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Cooling of the bus bar for ATLAS ( 3D model)
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Cooling of the bus bar for ATLAS (temperatures
distribution)
Air cooling
Water cooling
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Cooling of the bus bar for ATLAS (Heat transfer
coefficient)
Heat transfer to the cooling tube
Heat transfer to the air
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Thermal analysis of an ECAL electronic box
View of ECAL
Electronic box
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Thermal analysis of an ECAL electronic box
(context)

• Evaluate a proposed cooling solution which has to
  achieve the following requirements
• temperature variations of the crystal 0.1oC
• crystal temperature of about 16oC.
• Analysis of the influence of the fin/box thermal
  contact resistance.

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Thermal analysis of an ECAL electronic box(2D
model)
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Thermal analysis of an ECAL electronic box
(temperature distribution)

Fin/box contact resistance of 2.75x10-4 m2K/W
Fin/box contact resistance of 2.75x10-2 m2K/W
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Thermal analysis of an ECAL electronic box
(temperature distribution below the thermal
shield)
Fin/box contact resistance of 2.75x10-4 m2K/W
Fin/box contact resistance of 2.75x10-2 m2K/W
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Cooling of ALICE detector

• Evaluation of the solution proposed for the
  detector cooling.
• The main requirement is a temperature gradient
  inside the detector of 3oC.

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Cooling of ALICE detector (model)
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Cooling of ALICE detector (temperature
distribution)
Static model (no air flow)
Air flow at 10000 m3/h and 20oC
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Cooling of ALICE detector (velocity field)
Static model (no air flow)
Air flow at 10000 m3/h and 20oC
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Conclusions

• CFD helps to understand phenomena involved in
  situations where intuition or empirical
  calculations are useless.
• CFD can reduce the number of test.
• CFD is a cost and time saving tool if used
  adequately during the design process.