Comparison of sprinkler operation between experiments and numerical simulation using FDS

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Comparison of sprinkler operation between experiments and numerical simulation using FDS

 

Author: Wang, Yao
Title: Comparison of sprinkler operation between experiments and numerical simulation using FDS
Degree: M.Eng.
Year: 2014
Subject: Fire sprinklers.
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Building Services Engineering
Pages: xii, 133, 7 leaves : illustrations (some color) ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2760620
URI: http://theses.lib.polyu.edu.hk/handle/200/7642
Abstract: Nowadays, FDS is widely applied to study of the operation of sprinklers and fire detectors through simulation of convective motion of heated air flow and smoke plumes. The accuracy of computational simulation by FDS, however, is still needed to be validated by comparison of full scale experiments. The aim of this report is to study the ability of fire dynamic simulator (FDS) in predicting the distribution of temperature and smoke layer at pre-arranged ventilation conditions, as well as to verify the new established model for HRR measurement by means of comparing the results of the parallel experiments. In this research, FDS Version 6.0.0 is used for numerical simulation. In the experiments, pool fires are placed in different positions of the chamber with a pendent type of sprinkler and a specific ventilation, in order to demonstrate the influence of the parameters on the simulation. Fuel mass loss rate, temperature stratification, as well as hot gas layer distribution are recorded in groups by experimental situation in preparation for comparison with FDS simulation. In terms of the Vertical temperature profile above the fire, the height of 1m above the floor demarcates the performance of FDS prediction. FDS tended to underestimate the temperatures below 1m from the floor level with maximum error up to 150℃, except some periods close to fire extinguishment. In contrast, the upper temperatures of FDS simulation well matched the measured Vertical temperature profiles with smaller difference. Besides the hot gas Vertical temperature profile, comparisons of hot gas layer can be another reference for FDS validation. Temperatures of the upper two points of hot gas layers are well predicted by FDS simulation, but significant discrepancy still exist at lower part of the profile. As stated in discussion section, the difference of measured and simulated temperature may originate from experiment setup, which has been justified by extra simulation. In general, the newly developed method can be applied for measurement of HRR even after sprinkler activation by means of using an empty pan as a reference for the weight of collected water. FDS successfully predicted the Vertical temperature profile and hot gas layer distribution, but had bad performance in prediction of Vertical temperature profile after sprinkler activation and the flame temperature in periods close to fire extinguishment.

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