An investigation of the effect of make-up air velocity on smoke layer height with asymmetric openings and rotational air flow in atrium fires

Abstract

The results of full-scale tests of smoke interface height in atrium fires with different make-up air velocities and opening arrangements, including asymmetric openings and openings that resulted in rotational air flows, are presented in this paper. The non-symmetric opening arrangements included openings on 3 sides of the atrium, 2 adjacent sides and 1 side. Make-up air velocities of 1, 1.5 and 2 m/s and fire sizes of 1, 2 and 5-MW were considered. Temperature was recorded along the height of the atrium by setting up thermocouple trees, and the temperatures measurements were used to determine the experimental smoke interface height using the N-percentage method. Predicted smoke layer height from the atrium plume correlation is compared with the full-scale test data. The results show that even a 1 m/s make-up air velocity can cause a significant decrease in the smoke interface height in the case of an asymmetric opening arrangement and rotational air flows in the atrium. The full-scale test data are used to propose a correlation to calculate the reduction of smoke interface height for the design of smoke exhaust systems in atria.