Investigation on Film Formation Characteristics of Pressure-Swirl Nozzle

Abstract

The film formation during the spray/wall impingement has attracted more attention. The present study investigated the film formation characteristics of the pressure-swirl nozzle by applying the contact-free optical method. According to experimental results, the impingement distance had a slightly more significant effect on the actual spray angle than the mass flow rate, and the maximum changing value was 34.6°. The bulge at the center of the surface became insignificant with the impingement distance. The liquid film was divided into the raised zone, annular zone, and free flow zone. The maximum time-average thickness at the central position was 2.84 mm, and correlations for predicting the time-average thickness and surface roughness were fitted. The time-average thickness of the annular zone was 0.38–0.59 mm, relatively thinner than other zones. When the impingement distance was lower than 10 mm, the time-average film thickness and surface roughness in the annular zone and free flow zone decreased first and then increased with the impingement distance. However, effects of mass flow rates and impingement distance on the liquid film were negligible when the impingement distance was higher than 10 mm. The experimental findings are helpful to fundamentally understand the film formation during the spray/wall impingement.

Analysis of Film Forming Law and Characteristics for an Air Static Spray with a Variable Position of the Plane

“…From the above analysis, it can be seen that the careful selection of spraying height and spraying angle is essential to form a better coating distribution uniformity quality. In order to obtain an adjustable range of spraying height and spraying angle with good film distribution uniformity quality to meet the needs of trajectory planning of robot gun displacement spraying, the orthogonal test method is used to study the influence of spraying angle and height on film distribution uniformity at the same time [26]. In the range of spraying inclination angle from 0° to 30°, several groups of simulation experiments were With the increase in spraying height, the maximum coating thickness decreases in an approximately inverse function.…”