Numerical Simulation of Hydrogen Explosion Tests with a Barrier Wall for Blast Mitigation-Paper

We have investigated hydrogen explosion risk and its mitigation, focusing on compact hydrogenrefueling stations in urban areas. In this study, numerical analyses were performed of hydrogen blastpropagation and the structural behavior of barrier walls. Parametric numerical simulations ofexplosions were carried out to discover effective shapes for blast-mitigating barrier walls. Theexplosive source was a prismatic 5.27 m3 volume that contained 30%2hydrogen and 70%2air. Areinforced concrete wall, 2 m tall by 10 m wide and 0.15 m thick, was set 2 or 4 m away from the frontsurface of the source. The source was ignited at the bottom center by a spark for the deflagration caseand 10 g of C-4 high explosive for two detonation cases. Each of the tests measured overpressures onthe surfaces of the wall and on the ground, displacements of the wall and strains of the rebar inside thewall. The blast simulations were carried out with an in-house CFD code based on the compressiveEuler equation. The initial energy estimated from the volume of hydrogen was a time-dependentfunction for the deflagration and was released instantaneously for the detonations. The simulatedoverpressures were in good agreement with test results for all three test cases. DIANA, a finiteelement analysis code released by TNO, was used for the structural simulations of the barrier wall.The overpressures obtained by the blast simulations were used as external forces. The analysessimulated the displacements well, but not the rebar strains. The many shrinkage cracks that wereobserved on the walls, some of which penetrated the wall, could make it difficult to simulate the localbehavior of a wall with high accuracy and could cause strain gages to provide low-accuracy data. Aparametric study of the blast simulation was conducted with several cross-sectional shapes of barrierwall. A T-shape and a Y-shape were found to be more effective in mitigating the blast.