Structural fragments and explosions in industrial facilities: Part II – Projectile trajectory and probability of impact

Abstract When dealing with risk analysis, due to industrial explosions, it is required to collect and develop a detailed knowledge about the source terms (features of the generated fragments), the impact terms (fragment trajectory) as well as the target/projectile interaction. The present paper focuses on the fragment trajectory and the possible impact over industrial targets erected in the vicinity. A preliminary study (Part I) has been devoted to develop the probabilistic distributions for the source terms. According to the fragment features at their departure, from the source, the trajectory is evaluated under the combined effects of the inertia, the gravitation and the aerodynamics (drag and lift): translational as well as the rotational movements of the fragments are analyzed. Three fragment shapes, generated by either cylindrical or spherical vessels explosions, are investigated: end-cap, oblong end-cap and plate. For illustrative purposes, three target shapes are considered: cylindrical, ellipsoidal or cubic vessels that can be impacted by the generated fragments. Monte Carlo simulations are run in order to evaluate the probability of impact between the generated fragments and the vessels that are potential targets. Probabilities of impact on the ground as well as the kinetic energy at impact are evaluated according to the distance from the fragment source. The theoretical prediction of impacts risk is in good accordance with the statistical observations collected from a past industrial accident, for a set of more than 40 fragments that have been projected up to 1.2 km distance around the explosion source.