The influence of obstructions on ventilation in car park fires – Preliminary study

Abstract

A preliminary study on the influence of obstructions in the development of the flow, created by the ventilation system, is realized in this paper. A generic zone of an underground car park, with only one Jet Fan, was modelled considering different obstruction distances and different angle flow conditions at the exit of the Jet Fan, to quantify the impact of the obstruction on the flow efficiency and dispersion. The simulations were performed using Ansys Fluent, and the averaged system of momentum equations were solved with the Realisable k-ϵ turbulence model was applied. The wrong placement of the jet fan relative to the obstruction may affect the ventilators functioning within their vicinity. It was found that an angle of 7º with a distance of 8 times the obstruction height is a good trade-off when the obstacle is unavoidable.