Evaluation of two-phase flow models for accidental release and comparison with experimental data

International audienceUnderstanding the dynamics of a two-phase flow (liquid and gas) has been studied quite extensively over the past. This problem is indeed of direct relevance for many areas such as transportation, chemical processes and for the area of industrial risk assessment. For several years, INERIS has been conducting various experiments in order to understand the mechanisms of vaporisation during the release of products initially stored in the liquid phase, into the atmosphere. The purpose is to determine the gas fraction flowing not only in the pipeline but also in the released jet and the liquid fraction that could be trapped on the ground because of the presence of an obstacle. The studied products were propane, butane and ammonia. Various regimes of flows were tested and a database was created. Then, an evaluation of different models for calculating the two-phase flow and the droplet behaviour was based on flow regimes and experimental set-up. The first objective was to calculate the flow rate in the pipeline and predict the size of the droplets in the initial part of the jet. There was a wide scatter of the results and many difficulties arose during the determination of the flow evaporation rate. This paper presents the experimental results and conclusions on the validity of the twophase models depending on the products, experimental set-up, and pressure storage