Computational Analysis of Choices in the Design of Smoke Extraction Duct Systems (SEDS) for Compartment Fires.

Large Eddy Simulations (LES) of smoke extraction duct system (SEDS) in single compartments of different volumes (i.e., 128 m 3 , 512 m 3 and 2400 m 3 ) with FDS 6.5.3 are presented. The required grid resolution for accurate flow inside the duct systems is discussed and the influence of different SEDS design parameters (i.e., shape and position of duct system, number and position of extraction openings) on the smoke extraction efficiency of the system is analysed. The extraction rates applied to the SEDS are determined a-priori based on simplified calculations with these estimates compared against the predicted CFD results (i.e., in terms of predicted smoke free heights inside the compartments). Overall, the numerical predictions are satisfactory (i.e., within less than 5 % errors) in most of the scenarios considered, apart from the 2400 m 3 compartments, where the smoke free heights are 20 % lower than expected. The analysis of the numerical simulation results reveals some important aspects, including that the use of multiple extraction openings is not efficient, in terms of smoke extraction, in the same duct of the same compartment and that the local velocities, at the level of the extraction openings, can potentially exceed the maximum allowed design values. Among the SEDS design parameters, the position and shape of the duct (i.e., rectangular or flat) as well as the position of the extraction opening(s) do not have a significant influence in terms of predicted smoke free heights. [ABSTRACT FROM AUTHOR]