Smoke control in case of fire in a large car park: CFD simulations of full-scale configurations

Abstract

Computational Fluid Dynamics (CFD) simulation results are presented of full-scale car park fire experiments with smoke and heat control (SHC) by forced mechanical horizontal ventilation. A well-controlled liquid pool fire heat release rate (HRR) is set as an input parameter. The effect of the SHC system on the smoke movement in fire conditions is examined. The following parameters are varied: fire HRR; smoke extraction flow rate; openings for incoming air (so that different flow patterns have been created); presence of beams. The impact of jet fans (induction type) is also addressed in a number of simulations. The trends observed in the full-scale experimental campaign are well captured and additional insight is provided for the interpretation of the results. The sensitivity of the CFD results to input parameters is highlighted. For a 4MW HRR fire, which is the order of magnitude for a car fire, the required ventilation velocity to limit smoke back-layering in a flat ceiling car park is around 1.1m/s. When beams are present, the average velocity must be higher, particularly for longitudinal beams. If smoke is trapped inside a recirculation region, increasing the smoke extraction rate does not help to remove the smoke.