(52ae) Effect of Radiative Heat Transfer on the Consequences of Gas Cloud Explosions

During a typical premixed gas cloud explosion event, energy generated by the combustion of flammable gases and turbulence generated by the flame front propagation and gases expansion results in rapid pressure build-up. This pressure increase depends on the gas cloud volume, ignition location, gas mixture reactivity and surrounding geometry (confinement and congestion). In addition, the combustion generated flames also dissipate some energy due to radiative heat. Since gas cloud explosions are normally short lived, the effects of radiative heat do not have a significant impact for safety analysis, particularly for unconfined and large environments. However, for relatively small and confined environments, radiative heat can affect the pressure build up behaviour over time.

FLACS-CFD is a 3D modelling tool used for the simulation of gas dispersion, explosions and fires. When modelling gas cloud explosions, it has traditionally used a premixed combustion model and in general, radiative heat transfer effects are not considered. When simulating gas fires, it has included a non-premixed combustion model as well as two choices for radiative heat transfer modelling, such as the Six-Flux Model and the Discrete Transfer Method (DTM).

In this work, a recently implemented strategy for gas explosion modelling in FLACS-CFD is presented. It includes a unified combustion model that functions seamlessly for both non-premixed and premixed flames, enabling the inclusion of the existing fire radiative heat transfer models for gas explosion simulations. This new capability has been validated against HYJET experimental results in a pressurized enclosed tank, for various radiative hat transfer models, grid sizes and gas mixtures. Additional validations are currently being developed and should be available in the final version of the paper.