Large Eddy Simulation of Natural Extraction and Thermal Stratification Effects in Corridor Fires

The natural smoke extraction in a corridor with a vertical duct is analyzed numerically using the software Fire Dynamics Simulator. A parametric study is conducted to investigate the influence of the duct geometry (i.e. section, shape and height) on the smoke extraction efficiency. Results show that the section of the duct appears as the most influential geometrical parameter. There exists an optimal duct section, for which, the hot smoke adheres to the left and right walls of the duct. In this case, the mixing process and the stack effect are the dominating factors influencing the natural extraction performance. The thermal stratification is also investigated using the Newman parameter to quantify the smoke stratification stability. It was found that this parameter is predicted by the two-dimensional nature of the flow pattern in the downstream direction and that the degree of stratification decreases as the duct section and height increase.