(652f) CFD Simulation of Wind Effect on the Flammable Gas Cloud Formation from Two-Phase Flow Release

Flammable liquids are often handled in the industry and it is mandatory to classify the areas where it is likely to form explosive atmospheres according to international or national standards for hazardous area classification. In this regard, the assessment of risk scenarios involved in operations with liquefied gases is necessary. The use of numerical techniques such as Computational Fluid Dynamics (CFD) is recommended by the international standard IEC 60079-10-1 (2015) as an auxiliary tool in hazardous area studies. It allows accurate evaluation of specific risk scenarios including two-phase releases, enabling to verify the influence of different variables on the hazardous extent and zone types. In view of that, this work aims to evaluate the wind effect on the flammable gas cloud formation as a result of the release of liquefied propane from numerical experiments. The CFD model employed a multiphase Eulerian-Lagrangean approach and considered the condition of superheated liquid in the release. The wind speed was varied regularly up to 10 m.s-1, whereas the wind direction was modified with respect to the jet release direction. As a result, the gas cloud's extent and volume were obtained considering a critical concentration of interest as a boundary, defined as a fraction (0.5 – 1.0) of the Lower Flammability Limit (LFL) of the substance. Regardless of the direction, the increase in wind speed resulted in smaller flammable cloud volumes due to the dilution effect. A non-monotonic behavior was observed for the hazard extent when the wind and jet are in opposite directions, which occurs due to zero flow velocity. Furthermore, there was a tendency for the cloud to grow behind the release orifice when increasing the wind speed in the opposite direction to the jet, which is more prominent in lower critical concentrations. The results agree with others reported in the literature for gas emissions.