A comprehensive study on air transverse flow effects on the collision behavior of a supercooled water droplet

The impact of a supercooled droplet on a surface is a primary challenge of many industrial and aeronautical processes. However, in some cases, such as frost formation on vehicle windshields or wind turbine blades, the supercooled droplet collision does not occur in stagnant air. In this study, for the first time, the effects of the air transverse flow (ATF) on the thermal-fluid behavior of a supercooled droplet were investigated numerically. Also, different patterns of a superhydrophobic pillared surface were used in ۲۴ three-dimensional simulations in ANSYS Fluent software. The volume of fluid method is chosen for the simulation of the multiphase flow. The freezing model is improved by the supercooling temperature consideration method. The results show that the ATF velocity reduces the separation time exponentially and helps the droplet bounce from the surface before freezing inception. However, the excessive increase in ATF velocity has the opposite effect and may prevent the droplet from detaching the surface due to notable drag. The best value of the ATF velocity is obtained to be ۸ m/s , which reduces the separation time exponentially from ۱۶.۳ ms  to ۱۲.۵ ms  for a cold surface with a simple pillar pattern. The separation time is entirely affected by the simulation conditions and varies from ۱۱.۸۵ ms  to ۲۹.۲ ms . The maximum spreading factor, despite the separation time, is seriously influenced by the void fraction percentage of different pillared surfaces and varies from ۱.۵۳ to ۱.۶۹.

کلیدواژه ها:

Air transverse flow ، superhydrophobic pillared surface ، supercooled droplet ، impacting-freezing simulation ، vehicle windshields