The velocity distribution of the flow field in the centrifugal swirl atomization nozzle determines the atomization performance of the nozzle. With the VOF two-phase flow model and the RNG k - e turbu- lence model, the atomization of the hot water in the pipe through a swirl nozzle and its mixing with the su- perheated steam were simulated, and then the nozzle atomization field flow was obtained. The velocity dis- tributions of internal and external flow field were analyzed. The caculation results come to the following conclusion：After the fluid passes through the tangential hole in the centrifugal swirl nozzle, it becomes a swirling flow, spiraling forward. The liquid, once exiting from the nozzle outlet, rapidly changes from liquid column into liquid film with a certain cone shape, and then the liquid film is gradually atomized into drop- lets. For the rotating fluid inside the nozzle,its combined velocity and tangential velocity along the radial direction have similar distribution pattern, increasing first and then decreasing. As the cross section area of the flow changes, the change in velocity mainly occurs in the axial component, while the change in the tangential component is relatively small. When the fluid is atomized from the swirl nozzle, a recirculation region is formed near the center of the nozzle outlet. When the fluid in the pipeline reaches a certain flow rate, the recirculation region can be formed near the nozzle outer surface.
Journal of Engineering for Thermal Energy and Power
swirl nozzle, rotating fluid, velocity profile, recirculation region