Experiment And Simulation On Flow Field Of Swirl Nozzles

Swirl nozzles in liquid distribution device for desalination are researched in this paper. In order to study the different internal and external flow field of nozzles under the different operating parameters and the exit geometrical structure, experiment and numerical simulation have been applied.A test bed was set and precision pressure gauge and flow meter were installed. The conclusion can be got from experimental data that the nozzle flow increases with inlet pressure increases; the spray range increases with height increases within a certain height range. There is the maximum spray density in the center of water tray with the nozzle with deflector structure, while it is almost zero spray density with the swirl nozzle, and it shows a ring waters on the water tray. Condition spray cone angle slowly increases with flow rate increases, but the average spray cone angle has little change.To learn more about the internal flow field, the VOF model based on three-dimensional mathematical model in FLUENT6.3 was employed to imitate the hollow swirl nozzle in this article. The numerical result was compared with the experimental data and they agree with each other very well. The numerical simulation result shows that liquid film thickness is different at different positions in swirl chamber. There is an air cone in the central axis because low pressure in the center and air suction. The liquid film thickness becomes thinner with the radius become larger. In addition, the outlet velocity increases with inlet pressure increase and the velocity directions and pathlines of fluid field indicate that fluid flow out of the nozzle rotationally.Analysis nozzle with different exit diffusion angles, exit diameters and exit straight pipe lengths and we can draw conclusions that the larger diffusion angle is, the greater liquid cone angle appears and it's not the bigger the better about diffusion angle. There is an optimal value in actual application. The outlet velocity increases with diffusion angle increases. Air cone diameter decreases with nozzle diameter decreases, and there are two skips in velocity curves. One is in just entering the nozzle position, another is between nozzle export contraction and export expansion. Liquid closed to the exit of nozzle accelerates more rapidly with the nozzle diameter decreases and radial velocity on the outlet section becomes larger. Exit straight pipe length will affect exit velocity distribution.