Experimental Investigation on Lateral Temperature Profile of Window-Ejected Facade Fire Plume with Ambient Wind

Abstract

The present study investigated experimentally the lateral temperature profiles of window-ejected facade fire plume from compartment with external ambient wind normal to the facade. The previous reports only focused on no wind conditions that the entrainment and diffusion of ambient air with the fire plume, which determines this lateral temperature profiles, is controlled solely by the buoyancy of the plume itself. This could be essentially affected by the external ambient wind, however, has not been revealed or quantified in the past. Hence, in this work, reduced-scale experiments were carried out employing a cubic compartment with an opening (window) and a facade wall, subjected to ambient wind provide by a wind tunnel. The lateral temperature profiles of the fire plume issued through the compartment opening was measured by thermocouples arrays installed along the facade, for various opening dimensions and ambient wind speeds. Results showed that with increasing of wind speed, the temperature at a fixed position decreased gradually, especially at those positions near the facade; while the lateral decay of temperature at a given height was faster as the wind speed was higher. This was interpreted by the physics that the ambient wind normal to the facade enhanced the entrainment and diffusion of ambient fresh air into the plume. Then, a formula (based upon classic Gaussian function) was put forward to characterize the lateral temperature profiles of the facade fire plume, by using the modified effective characteristic plume thickness (a horizontal diffusion length scale) to include wind effect. The obtained data and proposed formula in the present study provide a basic understanding for the window-ejected facade fire plume characteristics with ambient wind.