Experimental and Modeling Uncertainty Considerations for Determining the First Item Ignited in a Compartment Using a Bayesian Method

Author(s):  
Jan-Michael Cabrera ◽  
Robert Moser ◽  
Ofodike A. Ezekoye

Abstract Fire scene reconstruction and determining the fire evolution (i.e. item-to-item ignition events) using the post-fire compartment is an extremely difficult task because of the time-integrated nature of the observed damages. Bayesian methods are ideal for making inferences amongst hypotheses given observations and are able to naturally incorporate uncertainties. A Bayesian methodology for determining probabilities to items that may have initiated the fire in a compartment from damage signatures is developed. Exercise of this methodology requires uncertainty quantification of these damage signatures. A simple compartment configuration was used to quantify the uncertainty in damage predictions by Fire Dynamics Simulator (FDS), and a compartment evolution program, JT-risk as compared to experimentally derived damage signatures. Surrogate sensors spaced within the compartment use heat flux data collected over the course of the simulations to inform damage models. Experimental repeatability showed up to 4% uncertainty in damage signatures between replicates . Uncertainties for FDS and JT-risk ranged from 12% up to 32% when compared to experimental damages. Separately, the evolution physics of a simple three fuel package problem with surrogate damage sensors were characterized in a compartment using experimental data, FDS, and JT-risk predictions. An simple ignition model was used for each of the fuel packages. The Bayesian methodology was exercised using the damage signatures collected, cycling through each of the three fuel packages, and combined with the previously quantified uncertainties. Only reconstruction using experimental data was able to confidently predict the true hypothesis from the three scenarios.

2008 ◽  
Vol 46 (2) ◽  
pp. 291-306 ◽  
Author(s):  
Jianping Zhang ◽  
Michael Delichatsios ◽  
Matthieu Colobert

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3099 ◽  
Author(s):  
Ho Trong Khoat ◽  
Ji Tea Kim ◽  
Tran Dang Quoc ◽  
Ji Hyun Kwark ◽  
Hong Sun Ryou

Understanding fire characteristics under sprinkler spray is valuable for performance-based safety design. However, fire characteristics during fire suppression by sprinkler spray has seldom been studied in detail. In order to present a fire suppression model by sprinkler spray and determine the fire characteristics after sprinkler activation in a compartment, a numerical analysis was conducted using a fire dynamics simulator (FDS). A simple fire suppression model by sprinkler spray was calibrated by comparing ceiling temperatures from experimental data. An extinguishing coefficient of 3.0 was shown to be suitable for the fire suppression model. The effect of sprinkler spray on the smoke layer during fire suppression was explained, revealing a smoke logging phenomenon. In addition, the smoke, which spread under the influence of the sprinkler spray, was also investigated. The temperature, velocity, and mass flow rate of the smoke layer through the doorway was significantly reduced during fire suppression compared to a free burn case.


2015 ◽  
Vol 763 ◽  
pp. 134-139 ◽  
Author(s):  
Cherng Shing Lin ◽  
Min Gen Wu ◽  
Sheng Min Tsai

A large number of factories have been sequentially established in Taiwan following the economic take-off several decades ago. However, this growth in number has led to the prevalence of fire hazards. Factory fires typically cause substantial casualties and property losses, and have therefore become a focal point for research. In the present study, the researchers employed the Fire Dynamics Simulator (FDS) software developed by the National Institute of Standards and Technology (NIST) to simulate and evaluate a factory fire scene in Taiwan. The fire continued for approximately 74 h, rendering this outbreak the single longest building fire and rescue in Taiwan. By analyzing relevant data, the researchers established a numerical model of the fire scene to simulate, evaluate, and analyze the influences that temperature, smoke conditions, and smoke layer height parameters had on the fire scene. The findings enabled the researchers to better understand the damage conditions that occur during fire outbreaks. The results of this case study can serve as a reference for designing and improving future fire prevention and safety plans.


2012 ◽  
Vol 531-532 ◽  
pp. 716-719
Author(s):  
Te Chi Chen ◽  
Chia Chun Yu ◽  
Cherng Shing Lin

Along with the economic growth, more crowded entertainment places are growing dramatically and the safety concerns are no longer contained as usual. The huge property damage and heavy casualties of fire caused by the owner ignorance of safety management or the fall short of the fire resistance specifications. These factors caused serious casualties after fire occurred. This research utilizes Fire Dynamics Simulator (FDS) software to analyze and simulate the fire accident that occurred in a public entertainment places on Po-Li bar, KeeLung City, Taiwan. The computer simulation calculates the fire spread and smoke distribution at the fire scene, and is in reasonable agreement with the post report provided by the fire department and photos. Simulation results of the various important parameters - such as temperature, CO concentration and smoke layer height during the fire time domain are obtained. This study will provide the improvement of fire parameters and suggestions to avoid future unfortunate events.


1996 ◽  
Vol 118 (3) ◽  
pp. 592-597 ◽  
Author(s):  
T. S. Zhao ◽  
P. Cheng

An experimental and numerical study has been carried out for laminar forced convection in a long pipe heated by uniform heat flux and subjected to a reciprocating flow of air. Transient fluid temperature variations in the two mixing chambers connected to both ends of the heated section were measured. These measurements were used as the thermal boundary conditions for the numerical simulation of the hydrodynamically and thermally developing reciprocating flow in the heated pipe. The coupled governing equations for time-dependent convective heat transfer in the fluid flow and conduction in the wall of the heated tube were solved numerically. The numerical results for time-resolved centerline fuid temperature, cycle-averaged wall temperature, and the space-cycle averaged Nusselt number are shown to be in good agreement with the experimental data. Based on the experimental data, a correlation equation is obtained for the cycle-space averaged Nusselt number in terms of appropriate dimensionless parameters for a laminar reciprocating flow of air in a long pipe with constant heat flux.


Author(s):  
Jong-Shang Liu ◽  
Mark C. Morris ◽  
Malak F. Malak ◽  
Randall M. Mathison ◽  
Michael G. Dunn

In order to have higher power to weight ratio and higher efficiency gas turbine engines, turbine inlet temperatures continue to rise. State-of-the-art turbine inlet temperatures now exceed the turbine rotor material capability. Accordingly, one of the best methods to protect turbine airfoil surfaces is to use film cooling on the airfoil external surfaces. In general, sizable amounts of expensive cooling flow delivered from the core compressor are used to cool the high temperature surfaces. That sizable cooling flow, on the order of 20% of the compressor core flow, adversely impacts the overall engine performance and hence the engine power density. With better understanding of the cooling flow and accurate prediction of the heat transfer distribution on airfoil surfaces, heat transfer designers can have a more efficient design to reduce the cooling flow needed for high temperature components and improve turbine efficiency. This in turn lowers the overall specific fuel consumption (SFC) for the engine. Accurate prediction of rotor metal temperature is also critical for calculations of cyclic thermal stress, oxidation, and component life. The utilization of three-dimensional computational fluid dynamics (3D CFD) codes for turbomachinery aerodynamic design and analysis is now a routine practice in the gas turbine industry. The accurate heat-transfer and metal-temperature prediction capability of any CFD code, however, remains challenging. This difficulty is primarily due to the complex flow environment of the high-pressure turbine, which features high speed rotating flow, coupling of internal and external unsteady flows, and film-cooled, heat transfer enhancement schemes. In this study, conjugate heat transfer (CHT) simulations are performed on a high-pressure cooled turbine stage, and the heat flux results at mid span are compared to experimental data obtained at The Ohio State University Gas Turbine Laboratory (OSUGTL). Due to the large difference in time scales between fluid and solid, the fluid domain is simulated as steady state while the solid domain is simulated as transient in CHT simulation. This paper compares the unsteady and transient results of the heat flux on a high-pressure cooled turbine rotor with measurements obtained at OSUGTL.


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