Modular phenomenological model for vented explosions and its validation with experimental and computational results

Abstract

The present study reports a modular engineering model for predicting peak pressure in vented explosions. Modelling assumptions are explained in detail and model components are validated against experimental and computational results. A basic version of this model is reported in our earlier paper (Sinha et al. [1]). Previous experimental and modelling efforts on vented explosion have primarily focussed on idealized condition of empty container with uniformly mixed fuel. However, in real accidents, there are often obstacles in flame path, and a leaked fuel may not get enough time to mix uniformly. These realistic accidental scenarios are accounted for in this extended model. The model is further simplified, and a final equation is proposed which depend on two fuel related parameters and two geometric parameters. Fuel parameters are pre-tabulated, and geometric parameters are easy to compute. Procedure to compute pressure generated by external explosion and internal pressure are outlined in detail. Experimental results available in open literature are used to evaluate model prediction capabilities. The model, in principle should be applicable for any gaseous fuel. However, the focus of the present investigation is to assess it for hydrogen explosions. In parallel to the modelling effort, a dedicated in-house solver HyFOAM is developed utilizing OpenFOAM platform. The HyFOAM predictions are validated against experimental results from the recently published test data involving hydrogen explosion in a 20-feet ISO container (Skjold et al. [2-4]). Moreover, as experimental investigations are expensive and require significant testing and safety infrastructure, a limited number of scenarios can be tested experimentally. In 2 addition to the experimental results, few more cases are simulated using HyFOAM and engineering model results are compared with the CFD results, and a reasonably good match is observed.