Numerical Modelling of Unconfined and Confined Hydrogen Explosion

Numerical studies were conducted with the objective of gaining a better understanding of the consequences of potential explosion that could be associated with release of hydrogen in a confined and unconfined environment. This paper describes the work done by us in modelling explosion of accidental releases of hydrogen, using our Fire Explosion Release Dispersion (FRED) software. CAM and SCOPE models in FRED is used for validation of congested/uncongested unconfined and congested/uncongested confined vapour cloud explosion respectively. In the first step, CAM is validated against experiments of varying gas cloud size, blockage ratio, equivalence ratio of the mixture and blockage configuration. The model predictions of explosion overpressure are in good agreement with experiments. The results obtained from FRED, i.e. overpressure as a function of distance, match well in comparison to the experiments. In the second step, SCOPE is validated against vented explosion experiments available in open literature. In general, SCOPE reproduces the maximum overpressure within the factor of 2. Moreover, it well predicts the trends of increase in overpressure with change in type of the fuel, increase in number of obstacles, blockage ratio and decrease in the vent size.