NUMERICAL SIMULATION OF CHOCKED TWO-PHASE FLOW FOR HAZARDOUS AREA CLASSIFICATION

Resumo

Two-phase flashing jet is the type of flow that results from the release of liquefied gas into
the atmosphere. The study of this multiphase release is of particular interest in industrial risk
assessments, especially when hazardous area classification analysis is applicable. The understanding of
those release phenomena using numerical techniques is relevant since it contributes with reliable data
when experimental setup of several scenarios is not feasible. Both the behavior and the characteristics
of these two-phase flow can significantly affect the hazard zone, it means that as more accurate the
flashing jet model is, the more rigorous is the definition of the hazardous area. Hence, this work aims to
propose a Computational Fluid Dynamic model to predict chocked two-phase flow, thus a more reliable
vapor cloud shape can be obtained. The Leung model was implemented for calculating critical
conditions of a propane leak, along with a Eulerian-Lagrangian approach for particle tracking and Shear
Stress Transport turbulence model in Ansys CFX® software. Simulation results show the plume extent
and volume within a safety factor of the lower explosivity limit, velocity and molar fraction profiles
along the jet axis, and shock wave prediction expressed through the Mach number profile. The present
work demonstrates that the predicted spread angle outcome is crucial to determine the plume volume
and, consequently, to quantify the risk factor.