دانلود رایگان مقاله بررسی عددی شعله های آتش در نمای پنجره بیرونی

Abstract

A numerical simulation was performed to assess the ability of the used code to model a compartment fire with external flames. Thereafter, numerical investigations were performed in order to study the influence of geometrical parameters such as opening dimensions, opening position and presence of sidewalls at the opening on window ejected flames. The influence of the heat release rate was also discussed. These studies highlight the different phenomena in each configuration and their influence on the risk of vertical fire spread. Moreover, to study the influence of sidewalls at the opening, numerical results were compared to Lu's correlation (Lu et al., 2013, 2014) [1,2]).

3. Conclusions

First of all, a numerical simulation was performed to assess the ability of the used code to model a compartment fire with external flames. Overall predictions were in relatively good agreement in terms of magnitude and distribution. Indeed, near-façade thermal ctions (position P) and flame thickness (position R) seem to be relatively well estimated by the model. However, some predictions were overestimated in the external combustion area induces an overestimation of the flame zone (position Q). We consider that the obtained results allow to properly study phenomena in the second part of this paper. Secondly, numerical investigations were carried out highlighted the influence of geometrical parameters such as opening dimensions, opening position from the room floor, the heat release rate and the role of sidewalls at the opening on window ejected flames. From the obtain results, we can retain that flame height decreases with increasing opening dimensions due to a better combustion inside the compartment. Moreover, it is also observed that the height of the opening has a great influence than the opening width. Opening positions has an influence on the flame height. The presence of a lintel leads to decrease flame height because it blocks the unburned gas inside the fire compartment. As expected, flame height significantly increases with HRR increasing due to a larger amount of fuel ejected through the window. Furthermore, to study the influence of sidewalls at the opening, numerical results were compared to Lu's correlation. The three studied cases were in good agreement with the correlation. It was observed that flame height decrease rapidly with D increasing but the influence of sidewalls could be observed for large distance of D (6.0 m). Additional simulations with larger HRR and different opening dimensions must be performed in order to study more precisely this parameter. Thus, a critical distance corresponding to the distance at which the sidewalls have no influence could be determined for several cases.