PRESENTATION OF CFD PRESENTATION OF CFD ACTIVITIES IN CV ACTIVITIES IN CV

GROUPGROUP

Daniel Gasser

What is CFD (1)?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 ...

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 ...)

What is CFD (2)? What is CFD (2)?

Goals of CFD studies in Goals of CFD studies in CV groupCV 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 ...

Current studies in CV Current studies in CV group 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.

Cooling of the bus bar for Cooling of the bus bar for ATLAS (context)ATLAS (context)

Compare the efficiency of air natural convection cooling with water cooling.

Choice of a simple cooling system.

Cooling of the bus bar for Cooling of the bus bar for ATLAS ( 3D model)ATLAS ( 3D model)

Cooling of the bus bar for Cooling of the bus bar for ATLAS (temperatures ATLAS (temperatures

distribution)distribution)

Air cooling Water cooling

Cooling of the bus bar for Cooling of the bus bar for ATLAS (Heat transfer ATLAS (Heat transfer

coefficient)coefficient)

Heat transfer to the cooling tube Heat transfer to the air

Thermal analysis of an ECAL Thermal analysis of an ECAL electronic boxelectronic box

View of ECALElectronic box

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.

Thermal analysis of an ECAL Thermal analysis of an ECAL electronic box (context)electronic box (context)

Thermal analysis Thermal analysis of an ECAL of an ECAL

electronic boxelectronic box(2D model)(2D model)

Fin/box contact resistance of 2.75x10-4 m2*K/W Fin/box contact resistance of 2.75x10-2 m2*K/W

Thermal analysis of an ECAL Thermal analysis of an ECAL electronic box (temperature electronic box (temperature

distribution)distribution)

Fin/box contact resistance of 2.75x10-4 m2*K/W Fin/box contact resistance of 2.75x10-2 m2*K/W

Thermal analysis of an ECAL Thermal analysis of an ECAL electronic box (temperature electronic box (temperature

distribution below the thermal shield)distribution below the thermal shield)

Cooling of ALICE Cooling of ALICE detectordetector

Evaluation of the solution proposed for the detector cooling.

The main requirement is a temperature gradient inside the detector of 3oC.

Cooling of ALICE detector Cooling of ALICE detector (model)(model)

Cooling of ALICE detector Cooling of ALICE detector (temperature distribution)(temperature distribution)

Static model (no air flow) Air flow at 10000 m3/h and 20oC

Cooling of ALICE detector Cooling of ALICE detector (velocity field)(velocity field)

Static model (no air flow) Air flow at 10000 m3/h and 20oC

ConclusionsConclusions

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.