Simulation of glazing behavior in fires using computational fluids dynamics and spectral radiation modeling

The performance and behavior of glazing systems have significant impact on fire growth and development. In the typical scenario of a glass pane exposed to fire, radiation is the predominant mode of heat transfer. In previous studies, the present authors have developed and validated a spectral radiation heat transfer model based on the Discrete Ordinates Method (SDOM) which accounts for the glass spectral properties (e.g. emissivity, transmissivity) and the diffuse nature of radiation incident on the glazing. In order to model the dynamic interaction between a glass pane and fire, the SDOM has been implemented in the CFD code FDS 5.0 and the new code (FDS-SDOM) is evaluated. The first part of FDS-SDOM validation study reports a comparative analysis between FDS-SDOM, the original (unmodified) version of FDS (OFDS) and the exact solutions for varying absorption coefficients typical of glass. The comparative study, in terms of radiative heat flux, shows that FDS-SDOM provides results closer to the exact solutions in comparison to OFDS when the absorption coefficient is varied from 0.1 to 100 m -1 (maximum error less than 1% for FDSSDOM against 13 % for FDS). This provides further justification for the need to account for varying spectral properties of material such as glass and the diffuse nature of radiation in calculations. In the second part of the validation study, FDS-SDOM is applied to two experimental fire and glass scenarios with the aim of predicting the transient temperature distribution in the glass. Relatively good agreements are found between the code’s predictions and the experimental data. The work demonstrates the good potential of combining the CFD approach with advanced spectral radiation modeling for fire and glazing studies.