TS/CV/DC CFD TeamTS/CV/DC CFD Team

CFD Simulation of a Fire in CFD Simulation of a Fire in

CERN Globe of Science and InnovationCERN Globe of Science and Innovation

Sara C. Eicher

CERN, CH

THE PROBLEMTHE PROBLEM

Sara C. Eicher

• The Globe is a spherical shape building made mainly of wood, with a crown vortex placed at its top. It consists of two floors and a basement room.

THE PROBLEMTHE PROBLEM

Sara C. Eicher

• The Globe is a spherical shape building made mainly of wood, with a crown vortex placed at its top. It consists of two floors and a basement room.

• The building is fitted with fire sprinkler, ventilation and smoke extraction systems.

THE PROBLEMTHE PROBLEM

Sara C. Eicher

• The Globe is a spherical shape building made mainly of wood, with a crown vortex placed at its top. It consists of two floors and a basement room.

• The building is fitted with fire sprinkler, ventilation and smoke extraction systems.

• Current emergency strategies to control smoke spread and evacuation are incomplete due to need to comply with established fire safety regulations.

THE PROBLEMTHE PROBLEM

Sara C. Eicher

• The Globe is a spherical shape building made mainly of wood, with a crown vortex placed at its top. It consists of two floors and a basement room.

• The building is fitted with fire sprinkler, ventilation and smoke extraction systems.

• Current emergency strategies to control smoke spread and evacuation are incomplete due to need to comply with established fire safety regulations.

• In the event of a fire in the first floor, the smoke extractor in place is believed to be inadequate for removal of the hot smoke accumulated in the ceiling of the first floor hall.

OBJECTIVESOBJECTIVES

Sara C. Eicher

• To evaluate the performance of current emergency smoke extraction strategies of the Globe in the event of a fire.

OBJECTIVESOBJECTIVES

Sara C. Eicher

• To evaluate the performance of current emergency smoke extraction strategies of the Globe in the event of a fire.

• To evaluate the effectiveness of installing hatches at the central vortex to provide natural smoke evacuation by comparison with the behaviour of the smoke system currently in place.

OBJECTIVESOBJECTIVES

Sara C. Eicher

• To evaluate the performance of current emergency smoke extraction strategies of the Globe in the event of a fire.

• To evaluate the effectiveness of placing hatches at the central vortex to provide natural smoke evacuation by comparison with the behaviour of the smoke system currently in place.

• To optimise the improved smoke evacuation system by investigating the effect of location, size and overall quantity of hatches to be placed within the constraints of the vortex geometry.

THE CFD MODELTHE CFD MODEL

Sara C. Eicher

• Only the first floor hall is modelled.

THE CFD MODELTHE CFD MODEL

Sara C. Eicher

• Only the first floor hall is modelled.

• The fire is represented by a non-spreading fluid region and modelled as quadratically increasing source of heat placed in the middle of the first floor. The combustion process was not simulated.

• The fire maximum heat output was set equal to 250kW/m3

THE CFD MODELTHE CFD MODEL

Sara C. Eicher

• Only the first floor hall is modelled.

• The fire is represented by a non-spreading fluid region and modelled as quadratically increasing source of heat placed in the middle of the first floor. The combustion process was not simulated.

• The fire maximum heat output was set equal to 250kW/m3.

• Overall geometry takes into account the lift cage, inner ramp and wall partitions, 2 exit doors and the smoke extractor.

THE CFD MODELTHE CFD MODEL

Sara C. Eicher

• Only the first floor hall is modelled.

• The fire is represented by a non-spreading fluid region and modelled as quadratically increasing source of heat placed in the middle of the first floor. The combustion process was not simulated.

• The fire maximum heat output was set equal to 250kW/m3.

• Overall geometry takes into account the lift cage, inner ramp and wall partitions, 2 exit doors and the smoke extractor.

• Fire sprinkler and ventilation systems are not considered.

• Smoke extractor assumed as a mass sink.

• Adiabatic wall conditions.

THE CFD MODELTHE CFD MODEL

Sara C. Eicher

• Only the first floor hall is modelled.

• The fire is represented by a non-spreading fluid region and modelled as quadratically increasing source of heat placed in the middle of the first floor. The combustion process was not simulated.

• The fire maximum heat output was set equal to 250kW/m3.

• Overall geometry takes into account the lift cage, inner ramp and wall partitions, 2 exit doors and the smoke extractor.

• Fire sprinkler and ventilation systems are not considered.

• Smoke extractor assumed as a mass sink.

• Adiabatic wall conditions.

• Calculation strategy: start from an isothermal steady state solution and use results as initial guess to transient calculation accounting for the development of the fire.

GEOMETRY & MESHGEOMETRY & MESH

Sara C. Eicher

• Mesh containing around 400,000 tetrahedral shape cells

• Two cases studied: Case A – without hatches (current design configuration)

Case B – with hatches at the crown vortex

• Transient model simulates 14 minutes of fire development

Lift Cage

Wall Partitions

Crown Vortex

Side Ramp

Exit Door

Exit Door

Wall PartitionsWall Partitions

Fire

RESULTS – TEMPERATURE FIELDRESULTS – TEMPERATURE FIELD

Sara C. Eicher

Case A Case B

RESULTS – VELOCITY FIELDRESULTS – VELOCITY FIELD

Sara C. Eicher

Case A

Case B

CONCLUSIONSCONCLUSIONS

• CFD model was able to predict the overall behaviour of the smoke extraction system currently in place, in case of a fire sprinkler failure.

Sara C. Eicher

CONCLUSIONSCONCLUSIONS

• CFD model was able to predict the overall behaviour of the smoke extraction system currently in place, in case of a fire sprinkler failure.

• Numerical results show expected temperatures stratification at the dome.

• Degree of stratification depends on the airflow pattern inside the hall, with temperatures at the ceiling up to 60˚C for case A.

Sara C. Eicher

CONCLUSIONSCONCLUSIONS

• CFD model was able to predict the overall behaviour of the smoke extraction system currently in place, in case of a fire sprinkler failure.

• Numerical results show expected temperatures stratification at the dome.

• Degree of stratification depends on the airflow pattern inside the hall, with temperatures at the ceiling up to 60˚C for case A.

• Installing of hatches at the vortex crown can improve the clearing of hot gases close to the ceiling, with temperatures about 20˚C lower than in the original configuration.

Sara C. Eicher

CONCLUSIONSCONCLUSIONS

• CFD model was able to predict the overall behaviour of the smoke extraction system currently in place, in case of a fire sprinkler failure.

• Numerical results show expected temperatures stratification at the dome.

• Degree of stratification depends on the airflow pattern inside the hall, with temperatures at the ceiling up to 60˚C for case A.

• Placing of hatches at the vortex crown can improve the clearing of hot gases close to the ceiling, with temperatures about 20˚C lower than in the original configuration.

• Both scenarios suggest that after 14 minutes of fire development, conditions at floor level remain acceptable for safe evacuation of people from the building.

Sara C. Eicher

sara.correia.eicher@cern.ch

CONCLUSIONSCONCLUSIONS

• CFD model was able to predict the overall behaviour of the smoke extraction system currently in place, in case of a fire sprinkler failure.

• Numerical results show expected temperatures stratification at the dome.

• Degree of stratification depends on the airflow pattern inside the hall, with temperatures at the ceiling up to 60˚C for case A.

• Placing of hatches at the vortex crown can improve the clearing of hot gases close to the ceiling, with temperatures about 20˚C lower than in the original configuration.

• Both scenarios suggest that after 14 minutes of fire development, conditions at floor level remain acceptable for safe evacuation of people from the building.

Sara C. Eicher

sara.correia.eicher@cern.ch