A Study on Optimizing Distance Between Fires

Sammanfattning

This report explores the interaction behaviour of fires for the further context of grocery stores or other shelfed enclosures. Inspired by Östlund and Troedson's work, which primarily examined temperatures above individual shelves, this research investigates the interaction between adjacent localized fires. Common assumptions in design calculations involve scenarios where fires are confined to single shelving units or have spread across multiple units. While the first scenario, with individual shelves, mirrors the work of Östlund and Troedson, the latter scenario introduces additional complexity due to additional seperate shelving units. The study delves into the background of fire safety in large, complex structures, focusing on deviations from traditional dimensioning methods. The primary objective is to understand the impact of distance between pool fires, contributing insights into fire interaction variables and optimizing shelf spacing for enhanced safety. The report builds on earlier studies, notably Östlund and Troedson's work, which proposed novel calculation methods for localized fires on shelves. It also draws from Maynard's research on fire interactions and pulsation, and Sandström, Sjöström and Wickström's study on thermal exposure in steel trusses, where the applied method with normal distribution in introduced. The methodology employs the Fire Dynamics Simulator (FDS) for computational simulations, emphasizing a proof-of-concept approach with a compromise on grid size for computational efficiency. Results from sensitivity studies and distance analyses between pool fires reveal intricate relationships influenced by fire width, intensity and spacing. The study introduces theoretical calculations based on 'method A' by Sandström, Sjöström and Wickström for centre line distances. These show both similarities and differences as compared to the temperature distribution from the FDS simulations. The FDS simulation shows greater divergence than results using 'method A', between 2- and 4meter centre line distances for interaction. Distance of interaction is defined as that distance where the temperature between is higher than that of the individual fires. In conclusion, the research underscores the significance of spacing considerations in fire safety engineering. The findings contribute valuable insights for practical applications, such as optimizing shelf placement in grocery stores to mitigate the risk of fire spread.