Fast Running Pool Fire Computer Code for Risk Assessment Calculations

2003 ◽  
Author(s):  
Miles Greiner ◽  
Ahti Suo-Anttila
Keyword(s):  
Heat Transfer ◽  
Reaction Rate ◽  
Volume Fraction ◽  
Radiation Heat Transfer ◽  
Soot Volume Fraction ◽  
Computer Code ◽  
Pool Fire ◽  
Temperature Measurements ◽  
Radiation Heat ◽  
Transportation Risk

The Isis-3D computational fluid dynamics/radiation heat transfer computer code was developed to simulate heat transfer from large fires to engulfed packages for transportation risk studies. These studies require accurate estimates of the total heat transfer to an object and the general characteris tics of the object temperature distribution for a variety of fire environments. Since risk studies require multiple simulations, analysis tools must be rapid as well as accurate. In order to meet these needs Isis-3d employs reaction rate and radiation heat transfer models that allow it to accurately model large-fire heat transfer even when relatively coarse computational grids are employed. In the current work, parameters for the reaction rate model were selected based on comparison with soot volume fraction and temperature measurements acquired in a recent 6 m square pool fire under light wind conditions. The soot volume fraction Isis-3D uses to define the edge of the optically thick fire was determined using temperature measurements of a pipe engulfed 20-m-diameter pool fire with a steady 9.5 m/s crosswind. Accelerated simulations, in which the specific heat of the engulfed pipe was reduced by a factor of twelve below the measured values, reproduce the temperature data in the 11-minute crosswind fire using only 3.5 hours on a standard desktop workstation.

Validation of the Isis-3D Computer Code for Simulating Large Pool Fires Under a Variety of Wind Conditions

2004 ◽  
Vol 126 (3) ◽  
pp. 360-368 ◽  
Author(s):  
Miles Greiner ◽  
Ahti Suo-Anttila
Keyword(s):  
Heat Transfer ◽  
Reaction Rate ◽  
Radiation Heat Transfer ◽  
Temperature Response ◽  
Computer Code ◽  
Computational Grids ◽  
Model Parameters ◽  
Pool Fires ◽  
Radiation Heat ◽  
Transportation Risk

The Isis-3D computational fluid dynamics/radiation heat transfer computer code was developed to simulate heat transfer from large fires to engulfed packages for transportation risk studies. These studies require accurate estimates of the total heat transfer to an object and the general characteristics of the object temperature distribution for a variety of fire environments. Since risk studies require multiple simulations, analysis tools must be rapid as well as accurate. In order to meet these needs Isis-3D employs fuel evaporation reaction rate and radiation heat transfer models that allow it to accurately model large-fire heat transfer even when relatively coarse computational grids are employed. Reaction rate and soot radiation model parameters in Isis-3D have been selected based on experimental data. In this work, Isis-3D calculations were performed to simulate the conditions of three experiments that measured the temperature response of a 4.66 m diameter culvert pipe located at the leeward edge of 18.9 m and 9.45 m diameter pool fires in crosswinds with average speeds of 2.0, 4.6, and 9.5 m/s. Isis-3D accurately calculated the time-dependent temperatures in all three experiments. Accelerated simulations were performed in which the pipe specific heat was reduced compared to the measured value by a factor of four. This artificially increased the speed at which the pipe temperature rose and allowed the simulated fire duration to be reduced by a factor of four. A 700 sec fire with moderately unsteady wind conditions was accurately simulated in 10 hours on a standard workstation.

CAFE-3D: A Fast Running Computational Tool for Analysis of Radioactive Material Packages in Fire Environments

2004 ◽  
Author(s):  
Narendra Are ◽  
Miles Greiner ◽  
Ahti Suo-Anttila
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Volume Fraction ◽  
Radiation Heat Transfer ◽  
Fire Behavior ◽  
Soot Volume Fraction ◽  
Radioactive Material ◽  
Computational Time ◽  
Fe Model ◽  
Transportation Risk

The Container Analysis Fire Environment (CAFE-3D) is a computer code developed at Sandia National Laboratories to simulate heat transfer from large fires to engulfed packages for transportation risk studies. These studies require accurate estimates of the total heat transfer to an object and the general characteristics of the object temperature distribution for a variety of fire environments. Since risk studies require multiple simulations, analysis tools must be rapid as well as accurate. In order to meet these needs, CAFE-3D links Isis-3D (a general purpose computational fluid dynamics/radiation heat transfer code that calculates fire behavior) to commercial finite element (FE) codes that calculates package response. In this scheme, CAFE-3D runs Isis-3D only periodically during the calculation to update local fire boundary conditions to the FE model. The frequency and duration of the fire update calculations are user controlled based on the fire time and/or package temperature rise. In this paper we outline various models employed by Isis-3D and the method for finding the soot volume fraction used to define the edge of the diffusively radiating fire zone. Then, the linkage between Isis-3D and the MSC P\Thermal finite element code is explained. Finally a benchmarking simulation, which reproduced the temperature data from the 30-minute light-crosswind fire using only 10 hrs of computational time on a standard workstation, is described.

Radiation Heat Transfer to the Leeward Side of a Massive Object Suspended Over a Pool Fire

2001 ◽  
Author(s):  
M. Alex Kramer ◽  
Miles Greiner ◽  
J. A. Koski
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Large Scale ◽  
Radiation Heat Transfer ◽  
Pool Fire ◽  
Windward Side ◽  
Leeward Side ◽  
Radiation Heat ◽  
Emissive Power ◽  
Inner Surface

Abstract A series of large-scale experiments were recently performed to measure heat transfer to a massive cylindrical calorimeter engulfed in a 30-minute circular-pool fire [1]. The calorimeter inner surface temperature was measured at several locations and an inverse conduction technique was used to determine the net heat flux. The flame emissive heat flux was measured at several locations around the calorimeter. Light winds of around 2 m/s blew across the calorimeter axis at the beginning of the test but diminished and stopped as the test continued. The winds tilted the fire so that the windward side of the calorimeter was only intermittently engulfed. As a result, the measured flame emissive power near the windward side was substantially less than the leeward surface. The variation of calorimeter temperature and heat flux was closely correlated with the measured flame emissive power.

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