Analysis of Pool Fires in Large Multi-Level Halls with the CFAST and FDS Fire Codes
M K. Dey
The analysis presented in this report was conducted for Benchmark Exercise # 2, Part II in the International Collaborative Fire Model Project (ICFMP). The analysis was conducted with CFAST Version 3.16, a zone model, and FDS Version 2, a computational fluid dynamic model developed by the National Institute of Standards and Technology. The objective of the second benchmark exercise was to examine scenarios that are more challenging for zone models, in particular to fire spread in a multi-level large volume representative of turbine halls in nuclear power plants. FDS, including its output processor Smokeview, provides a comprehensive tool to examine the phenomena involved in the scenarios, specifically for examining the flow patterns through the hatches and ventilation systems. CFAST is a computationally efficient tool, providing the ability to determine solutions to problems within minutes; however, modeling horizontal vents in CFAST posed a challenge. Techniques are available to overcome this challenge. Bounding analyses of such scenarios with a zone model is also an option available to users. The ventilation in the scenarios examined significantly affects the flows, temperature, and other conditions in the compartments. The target temperatures are lower for ventilated conditions. Natural ventilation is more effective in preventing adverse compartment conditions for material targets and the human operator for the ventilation specifications given for the benchmark exercise. The codes predicted that the beam and cable targets would not reach damage temperatures for the scenarios examined.
Analysis of Pool Fires in Large Multi-Level Halls with the CFAST and FDS Fire Codes, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD
(Accessed December 3, 2023)