MODELING THE THERMAL RADIATION PENETRATION INTO THE LIQUID FUELS FOR FIRE SIMULATIONS

F. Alinejad*, H. Bordbar, S. Hostikka

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Abstract

In-depth radiation absorption is one of the main mechanisms for liquid fuels evaporation in fires. The common approach in modeling of thermal radiation for liquids is applying the constant absorption coefficient (i.e., gray method) in solving the radiative transfer equation (RTE) and same reflectivity values at different sides of the interfaces. This approach neglects the spectral nature of the absorption coefficient and redistribution of the penetrated thermal radiation at the interfaces. To consider the spectral nature, we previously presented a novel gray modeling that accounts the absorption spectra. This physics-based gray method applies different values for the absorption coefficient based on the flame temperature and depth from the sample surface. For the interface effect, equivalent reflectivity is introduced at different sides of the interface applying the Fresnel relation. The new method was implemented into Fire Dynamics Simulator (FDS) that is an open-source CFD software for fire-driven flows. Simulations were done using 1040 cores on a supercomputer applying around 5.8 million grids for a 10×7×5 m3 room with two sizes of the heptane pools. Results showed that new approach could predict the measured burning rates for heptane pools. At the initial stage of the burning, the common approach underestimates the burning rate, while at the last stage it overestimates the burning rate compared to the new approach. The new approach brings the detailed radiation physics into the account and solves the issue of applying unrealistic values for the absorption coefficient and reflectivity in fire simulations.

Original languageEnglish
Title of host publication8th Thermal and Fluids Engineering Conference (TFEC)
PublisherAmerican Society of Thermal and Fluids Engineering
Pages945-954
Number of pages10
Volume2023-March
DOIs
Publication statusPublished - 2023
MoE publication typeA4 Conference publication
EventThermal and Fluids Engineering Conference - Hybrid, College Park, United States
Duration: 26 Mar 202329 Mar 2023
Conference number: 8

Publication series

NameProceedings of the Thermal and Fluids Engineering Summer Conference
ISSN (Electronic)2379-1748

Conference

ConferenceThermal and Fluids Engineering Conference
Abbreviated titleTFEC
Country/TerritoryUnited States
CityCollege Park
Period26/03/202329/03/2023

Keywords

  • burning rate
  • interface effect
  • physics-based gray method
  • pool fire
  • spectral absorption coefficient

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