Conference paper Open Access
Vented deflagrations are one of the most common and simplest methods to reduce damages that might be caused to buildings and enclosures due to accidental explosions. Various engineering models are available in the literature in the form of published papers, European and USA standards. However, none of these have been sufficiently validated for the vented explosions of hydrogen-air mixtures, especially for realistic explosion scenarios in the presence of obstacles. In addition, a new engineering model based on external cloud explosions (ECE) has been developed by the authors. The foundation of the ECE is the proposed new methodology to calculate the external cloud formation, which is described in another paper (Sinha and Wen, 2018a) also submitted to this conference. The present paper further describes the following up procedures to calculate both the overpressures generated by the external cloud combustion and internal explosion. . The model has also been extended to cover the vented explosions in the presence of obstacles by accounting for the increase in flame surface area due to the presence of obstacles. In parallel to the above, HyFOAM has been developed in house as a dedicated solver for vented hydrogen explosions within the frame of the open source computational fluid dynamics (CFD) code OpenFOAM. The code uses the flame wrinkling combustion model for modelling turbulent deflagrations. Additional sub-models have been added to account for lean combustion properties of hydrogen-air mixtures. In the present study, the overpressure predictions from the various engineering models and the HyFOAM code will be compared with the recently published test data involving hydrogen explosion in a 20-feet ISO container (Skjold et al., 2017a, 2017b).