Numerical and experimental investigation on the effect of heat release rate in the evolution of fire whirls

A. Cantizano, P. Ayala, E.M. Arenas, J.R. Pérez-Domínguez, C. Gutiérrez

Case Studies in Thermal Engineering Vol. 41, pp. 102513-1 - 102513-12

Summary:

Buildings with large internal spaces, such as vertical shafts or atria, are widespread nowadays. In the case of fire, internal air currents may generate devastating fire whirls that can cause severe damage due to intensive heat release rate (HRR) and temperatures. This work presents the generation and evolution of fire whirls in a full-scale atrium experiment and their comparison with a numerical approach. A set of numerical models using FDS 6.7.5 are tested to assess the influence of the HRR curve and the impact of intrusive methods of temperature measurements on the prediction of whirls. The results show that the Burgers vortex model is well reproduced, although the continuous flame and plume regions can only be distinguished with fine grids. However, the periodic evolution of the whirls is better predicted with a time-averaged HRR curve, showing its influence on the flame height. The use of the experimental HRR curve presents more accurate results only in the temperatures far from the flame, with errors lower than 8.5% even for coarse grids. In addition, a small obstacle above the flame is observed to affect the formation of the whirls, which consequently impacts the grid sensitivity and computational cost.

Spanish layman's summary:

Actualmente se construyen muchos edificios con grandes espacios internos. En caso de incendio, las corrientes de aire pueden generar tornados de fuego que pueden causar daños. Este trabajo presenta la generación de estos tornados en un atrio a escala real y su comparación con FDS 6.7.5.

English layman's summary:

Buildings with large internal spaces, such as vertical shafts, are widespread nowadays. In the case of fire, air currents may generate fire whirls that can cause damage. This work presents the generation of fire whirls in a full-scale atrium and their comparison with FDS 6.7.5.

Keywords: Fire whirl; Heat release rate; Atrium; Full-scale experiments; FDS; Intrusive measurements

JCR Impact Factor and WoS quartile: 6,800 - Q1 (2022)

DOI reference: https://doi.org/10.1016/j.csite.2022.102513

Published on paper: January 2023.

Published on-line: October 2022.

Citation:
A. Cantizano, P. Ayala, E.M. Arenas, J.R. Pérez-Domínguez, C. Gutiérrez, Numerical and experimental investigation on the effect of heat release rate in the evolution of fire whirls. Case Studies in Thermal Engineering. Vol. 41, pp. 102513-1 - 102513-12, January 2023. [Online: October 2022]