The impact of atrium shape on natural smoke ventilation

Abstract

The performance efficiency of natural smoke ventilation in atria spaces are influenced greatly by several design decisions such as atrium shape, height, size and openings location. This paper investigates the impact of atrium shape (horizontal profile) on smoke ventilation performance in naturally ventilated atria. Three different configurations (square, rectangular and triangular prism) with the same area, height, and hence, volume were tested. The smoke ventilation performance is being assessed in terms of smoke filling time using a computational fire dynamic simulator (FDS). FDS is used to simulate the natural smoke filling resulting from atrium fire in the three configurations. The smoke layer interface height as a function of time and soot mass fraction and temperature as a function of height have been registered during the simulation. The predicted transport lag time for initial formation of the smoke layer beneath the ceiling (ceiling jet) was compared for the three tests. In order to test sensitivity of the shapes, all other parameters were designed to be similar in the three tests, and the same fire scenario was applied including inlet and outlet area, and fire size and location. The results showed that the rectangular configuration contributes better to smoke ventilation, and that the triangular configuration is the most critical in terms of smoke filling time, followed by the square configuration.