Toward a detailed understanding of the rocket propulsion process and prediction on the trajectory of a boiling liquid expanding vapor explosion (BLEVE)

To mitigate the hazards of fragments during a runaway reaction explosion or a boiling liquid expanding vapor explosion (BLEVE), an accurate estimate of the maximum kinetic energy of the fragments and the trajectory is critical. On June 13, 2020, an LPG tanker truck slanted over and exploded on the highway interchange at Wenling, Zhejiang Province, China. A BLEVE occurred initially, with the cylindrical vessel rupturing into one end-cap and one rocket-like vessel. The 12-ton rocket-like projectile was thrown 364 m away, resulting in an LPG vapor cloud larger than 300 m, followed by several explosions ultimately. It provided a good opportunity to study the ‘rocket’ BLEVE process and to evaluate the potential trajectory model. Image analysis technique and 3D modeling using SketchUp were employed to reconstruct the spatial and temporal information in the accident, by comparing the Sketchup model with the accident video information processed by MATLAB. An accurate trajectory of the fragment was reconstructed, giving the projectile velocity to be 170–176 m/s and the averaged trajectory angle around 8°. The BLEVE process was further modeled using a two-phase flow discharge model together with a rocket propulsion model, and the predicted results fit well with those as estimated by the reconstructed model. The trajectory of the fragment was also modeled using the projectile velocity and trajectory angle, together with discussion on the effects of air drag resistance, which provided a good prediction and fit well with the trajectory in the SketchUp model. •The spatial and temporal information in the accident were reconstructed by image analysis technique and SketchUp 3D model.•BLEVE process was modeled using a two-phase flow discharge model together with a rocket propulsion model.•The fragment's trajectory was modeled by projectile velocity and trajectory angle, with consideration of air drag resistance.