- Author
- Ingason, H. | Persson, B.
- Title
- Effects of Wind on Natural Fire Vents.
- Coporate
- Swedish National Testing and Research Inst., Boras, Sweden
- Report
- SP REPORT 1995:04; BRANDFORSK Project 055-921, 1995, 39 p.
- Keywords
- wind effects | vents | shopping centers | industrial buildings | literature surveys | roofs
- Identifiers
- Computational Fluid Dynamics (CFD)
- Abstract
- Natural fire ventilation may under certain conditions be completely overridden by forces created by external wind. Thus, there is a need to be able to predict the effects of wind on the performance of fire vents. The present report gives a survey of the literature and reviews both experimental and theoretical work. A modified version of an existing simple theoretical model is presented. The model can serve as a tool for parametric studies of the influence of external wind and inlet openings. Calculations with CFD were carried out for a typical shopping mall with a pitched roof and an industrial building with a flat roof. The calculations for the shopping mall, carried out in two dimensions for simplicity, show a substantial influence of wind on the efficiency. These two-dimensional results can only be regarded as qualitative, but they clearly show the expected tendencies of the two different fire vent designs considered. The simulations of the flow in the industrial building have been carried out in three dimensions. They show that the efficiency, in the case of one vent open, is reduced by a factor of two when increasing the wind speed from zero to twenty meter per second. In the simulations it was assumed that the fire vents had no kerbs. The main objective with the simulations was to investigate the possibility of using CFD to calculate the simultaneous effects of external wind and fire within a building. The simulations clearly demonstrate the feasibility of using CFD as a tool in both designing fire vents and in evaluating the performance. At the present stage CFD can advantageoulsy be used in parametric studies. However, further work is needed in validating the codes before they can be used in design work without any support of experiments.