EFFECT OF OPERATING CONDITIONS ON FLUID FLOW OVER A HIGH SPEED ROTARY BELL-CUP ATOMIZER

Using the volume of fluid (VOF) method, we analyze two-dimensional fluid flow over high-speed rotary bell-cup atomizers. The fluid behavior is analyzed and the liquid film thickness is quantitatively evaluated. The atomizer is flat in shape and has a paint supply hole. The bell rotational speed obtained is 15,000, 25,000, and 35,000 rpm; and the liquid flow rate obtained is 150, 300, 450, and 600 mL/min. The liquid used in this experiment is assumed to be water and the gas is assumed to be air. The results show that the liquid flows through the bell-cup surface toward the edge and forms a liquid film. At the measuring point, the film is initially thick but it then decreases to a practically constant value. The increase in the bell rotational speed causes the film thickness to decrease. Furthermore, the increase in the rotational speed causes the film thickness to become constant, whereas the increase in the liquid flow rate causes the film thickness to increase. These results show that the rotational speed and flow rate strongly affect the thickness of the film.