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ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
A PRELIMINARY DESIGN OF NUMERICAL EXPERIMENTS STUDY ON THE INFLUENCE OF FACTORS AFFECTING THE FIRE SPREAD IN BRAZILIAN INFORMAL SETTLEMENTS (FAVELAS)
Submission Author:
Calisa Lemmertz , RS
Co-Authors:
Calisa Lemmertz, Rodolfo Prediger Helfenstein, David Rush, Felipe Roman Centeno
Presenter: Calisa Lemmertz
doi://10.26678/ABCM.ENCIT2022.CIT22-0450
Abstract
Informal Settlements (IS), also known in Brazil as favelas, are under constant risk of large scale fires, which may affect hundreds of people at the time. Some of the Informal Settlements' main characteristics, which are commonly seen in IS all over the world, such as close proximity of the dwellings, irregularity of lanes and alleys, and large availability of combustible material contribute to a larger fire spread rate when compared to other urban areas. From previous works, it is already known that the presence of atmospheric wind can enhance the severity of a fire and contribute to its spread. For this reason, in this study, we analyze the factors that contribute the most to the fire spread in informal settlements subjected to atmospheric wind. To do this, a screening study applying design of experiments for numerical simulations was conducted. For the design of the numerical experiments, the space-filling design known as Latin Hypercube Design (LHD) technique was applied and the results were analyzed using Gaussian Process. It is known that fires frequently spread to adjacent structures by heat flux or flame impingement, thus, the studied parameters (responses) were the hot gas temperature inside the fire dwelling, the incident radiative heat flux in a neighboring dwelling, and the flame horizontal projection ejected through the fire dwelling’s opening. The studied factors were the wind speed and direction, and the separation distance between dwellings. The dwellings were modeled as thermally-thick compartments, which better represent masonry dwellings, commonly found in Brazilian Informal Settlements. The simulations were performed in a CFD code called Fire Dynamics Simulator (FDS) and the IS was represented by an array of nine dwellings to allow the wind flow to be affected by the presence of these obstacles (dwellings), creating “wind tunnel effects”. This study allowed us to understand which of the studied factors have a more important influence on the fire spread, and also how the interactions between these factors affected the fire spread in Informal Settlements. Knowing the dynamics of the fire spread in Informal Settlements will help us in the future to propose interventions that may reduce the risk of fire spread in these communities.
Keywords
fire spread, Informal Settlements, atmospheric wind, FDS, design of experiments
