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Highlights: [•] Full-scale experimental data of atrium fire tests. [•] Assessment of stair stepping on the smoke layer and temperature field. [•] Validation of CFD numerical model FDS. [•] Numerical study for different area-to-height-squared ratio atria. [•] Good agreement between experiments and numerical simulations, especially far away from the fire source and the centerline. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the thermal performance of various shapes and geometries of atriums in buildings is examined under various conditions. The goal of the study is to assess the impact of the atrium shape on the building total energy consumption and to identify the most energy-efficient atrium design. The study focuses on four different central atriums types with square and rectangular geometries which have same areas, use, schedule, controls, occupancy, and construction. The atriums exhibit different aspect ratios (length to width). Four cities in United States are selected to represent primary climatic regions of hot-dry, hot-humid, cold, and temperate. Besides, the atrium height, the atrium glazing type, and the glazing ratio are varied throughout the simulation process. Buildings models are constructed using the DOE-2.1E building energy simulation program. The results of this study indicate that in general, the total energy consumption of the narrow, elongated atrium or the rectangular atrium with high ratio of length to width is significantly greater than the square shaped atrium. [Copyright &y& Elsevier]

Abstract: The present paper is focused on the fluid dynamics of the make-up air at the vents in case of an atrium fire, its influence on the fire-induced conditions and the necessity of properly modelling it to obtain a reliable numerical prediction. For this aim, experimental data from two full-scale atrium fire tests conducted in a 20m cubic facility, with venting conditions involving mechanical smoke exhaust and make-up air velocities larger than 1m/s, and with different fire powers, are presented. Subsequent numerical simulations of these tests have been performed with the code Fire Dynamics Simulator v5.5.3. Two different approaches have been followed to simulate the make-up air inlet fluid dynamics, involving one domain which only considers the inside of the building and another which includes part of the outside. In the former simulations, anomalous phenomena around the fire appear, while the inclusion of part of the exterior domain results in completely different fluid dynamics inside the facility, which agrees better with the experimental data. A detailed analysis of the fluid mechanics at the air inlet vents is conducted to explain these discrepancies. Finally, further simulations are performed varying the make-up area and the exterior extension to assess the appearance of the aforementioned phenomenon. [Copyright &y& Elsevier]

This paper presents an investigation on the scenarios of the natural smoke filling times in an atrium due to a located floor fire. Based on the Heskestad's correlation, the heat release rate and the effective height of the fire source were transformed into an equation associated with the diameter and perimeter of the fire source. Neglecting the thermal effect for heat release due to relatively small temperature rise in the atrium and applying the assumption of mass conservation, the height of smoke layer interface can be derived. In this study, the various plume models such as McCaffrey's correlation, Zukoski's correlation, Thomas's correlation and NFPA 92B's correlation are considered with both steady fire and unsteady fire situations. The comparisons between the theoretical results and the experimental data were also made and discussed. [ABSTRACT FROM AUTHOR]