Numerical Simulation of Atomization Characteristics of Perfluorohexanone under Low-Pressure Environment

Abstract

Since perfluorohexanone can play a role in cooling and extinguishing the heat loss of lithium batteries, it is urgent to study the atomization characteristics of perfluorohexanone in different ambient pressures (49 kPa, 75 kPa, 101 kPa) to ensure the flight safety of all-electric aircraft in the future and the storage and use the safety of lithium-ion battery in high plateau areas. The process of the primary and secondary breakup was studied by using the VOF-DPM model, and the influence of different environmental pressures on the development of atomization and its atomization characteristics was analyzed. The results showed that the primary breakup of the perfluorohexanone liquid sheet was caused by Kelvin Helmholtz/Rayleigh-Taylor (KH-RT), while the secondary breakup was mainly caused by RT instability. Under different environmental pressures, the Sauter Mean Diameter of (D32) along the spray axis decreases sharply at first and then increases slowly. As the air density decreases with the decrease of air pressure, D32 gradually increases, resulting in the decrease of atomization mass. Moreover, when the atomization drops from 101 kPa to 49 kPa, D32 of droplets increases by 38% to 51%, which is conducive to providing evidence for the effectiveness of perfluorohexanone in fire extinguishing under low-pressure conditions.