Numerical model and validation experiments of atrium enclosure fire in a new fire test facility

Abstract

The use of computational fluid dynamics (CFD) as a tool for buildings, warehouses or factories design requirements fulfilling about fire safety is becoming more common and reliable. Performance-based fire safety assurance procedures make use of the CFD fire modelling to anticipate the evolution of fire, but they need always to be validated. This is especially difficult for big structures, with great clear volumes, where effects of natural and forced ventilation can be very scale dependent. A good opportunity to check the prediction capability of CFD codes to establish temperatures and velocities fields is the new full-scale fire test facility of the Technological Metal Centre in Murcia, Spain. It is an aluminium prismatic squared base building of 19.5 m×19.5 m×20 m, with several vents arranged in its walls and four exhaust fans at the roof. Series of experimental tests have been carried out using several heptane normalized pool-fires placed at the centre of the atrium. The data obtained from these experiments have been later used in a validation study of two CFD simulations implemented for temperature wall, ambient temperature prediction and exhaust fan assessment. The results show good agreement between experimental and numerical predictions and allow concluding that for a fire test of 1.6 MW of average heat release power, the exhaust and ventilation system is not enough to extract the hot combustion products. There is an excessive and dangerous accumulation of hot gases at the upper part of the atrium and the exhaust capacity of the roof fans must be increased. The CFD models can give the answer to that question.