CFD study of relation between ventilation velocity and smoke backlayering distance in large closed car parks

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

“…The notation for the configurations is introduced in Table 2 Decreasing the extraction rate with constant fire HRR results in an upstream shift of the position of maximum temperature, as well as a temperature increase due to reduced cooling by the incoming fresh air ( Figure 6). The effect of the extraction rate is stronger than the effect of the fire HRR, as is also reflected in the correlation of [16] and as has been observed in [1].…”

Smoke and heat control for fires in large car parks: Lessons learnt from research?

“…It is explicitly mentioned that recirculation and stagnation regions of more than 15m must be avoided (which is consistent with the observation that smoke is trapped in such regions and the performance criterion stated in [17], namely that the fire service must have smoke-free access to a distance of maximum 15m from the fire source). Moreover, using information from [18], the required ventilation velocity decreases with increasing car park width (from 1.5m/s for widths of 8m or less down to 1.0m/s for widths of 26m or more). (In [18], the width dependence has been confirmed, but the final expression given in [18] for the required ventilation velocity has been made independent of the car park width in a conservative manner; this is not essential for the paper at hand.)…”

“…Moreover, using information from [18], the required ventilation velocity decreases with increasing car park width (from 1.5m/s for widths of 8m or less down to 1.0m/s for widths of 26m or more). (In [18], the width dependence has been confirmed, but the final expression given in [18] for the required ventilation velocity has been made independent of the car park width in a conservative manner; this is not essential for the paper at hand.) The width of smoke zones is furthermore essentially limited to 32m.…”

“…Details on the full-scale experimental set-up and numerical simulations carried out at Ghent University are given in [9,10,18]. It is important to appreciate the full-scale experimental set-up, so that the observations as described below are not generalized to any, potentially complex, car park configuration or to situations where the fire source is in the direct proximity of a wall.…”

“…-For unidirectional air flows (and for unidirectional flows only) and in the absence of beams under the ceiling, a simple single-line formula [18] can be used to calculate the required extraction rate, corresponding to a certain distance of smoke back-layering from the fire source (which is assumed not to be positioned close to a wall in [18]). …”