Abstract: In order to analyze the atomization performance of perfluorohexanone fire extinguishing agent at different ambient temperatures, the atomization cone angle, liquid film crushing process and particle size distribution characteristics of perfluorohexanone spray at four ambient temperatures (5, 15, 25, 35 ℃) were studied by using the coupled numerical simulation method of VOF and DPM. The results show that with the increase of ambient temperature, the tangential velocity and centrifugal force of perfluorohexanone at the nozzle outlet increase, and the atomizing cone angle increases gradually. When the temperature increased from 5 ℃ to 35 ℃, the air viscosity increased by 11.76%, the surface tension of perfluorohexanone decreased by 23.08%, the gas-liquid force intensified, and the penetrating distance of perfluorohexanone liquid film in the spray space was shortened by 20%. The droplet particle size was smaller when perfluorohexanone liquid film was broken at one time, which resulted in a significant decrease in the Sott mean diameter of droplet. With the development of spraying process, large size droplets of perfluorohexanone (240~320 μm) were further broken into a large number of small droplets, and the size distribution of the spray droplets became more uniform in space.

Key words: ambient temperature, perfluorohexanone, VOF-DPM, spray cone angle, breaking process, particle size distribution