Investigation on Spray Morphology, Droplet Dynamics, and Thermal Characteristics of Iso-Pentane Flashing Spray Based on OpenFOAM

Abstract

Leakage of high-pressure hydrocarbon liquid from a vessel or pipe may easily result in a two-phase flashing spray due to the rapid pressure drop, which might produce catastrophic consequences. Understanding the flashing spray process is essential to prevent these consequences and minimize the impact. This paper conducted a numerical study through OpenFOAM to investigate the two-phase behavior of flashing spray using a volatile and flammable substance of iso-pentane. The evolution of spray morphology and the distributions of droplet temperature, diameter, and velocity under various initial injection pressures (Pinj) and temperatures (Tinj) were investigated. The simulation result showed good agreement with the experimental result in spray morphology under various Pinj and Tinj. The simulation results indicate that a higher Pinj causes a larger gas phase diffusion length, while Tinj contributes little to this length. However, increasing the Pinj and Tinj shortens the liquid penetration distance. Near the nozzle exit field of about 10 mm, liquid droplets experience a rapid decrease in diameter and velocity along the spray central axis. Meanwhile, spray presents an obvious expansion via the introduction of a spray angle as the input boundary condition of the simulation and droplet temperature has a large gradient toward the radial direction within this field. Droplets in the spray’s downstream region achieved a more stable state with less change in droplet diameter, velocity, and temperature.