EXPERIMENTAL INVESTIGATION OF THE ATOMIZATION CHARACTERISTICS OF ANTICORROSION WAX

Abstract

We investigated the spray characteristics of continuous-flow nozzles using anticorrosion wax. Based on particle image velocimetry (PIV) and phase Doppler particle analyzer (PDPA) experiments during spray injection, we calculated the velocity field of the entire spray and analyzed the atomization processes. All experiments were performed under ambient conditions (atmospheric pressure and room temperature) with an injection pressure of 10 MPa. For the PIV experiment, a frequency-doubled Nd:YAG laser having 25 mJ/pulse energy and a time interval of 30 s and a CCD camera synchronized with the laser pulse were used. The captured images from the CCD camera were processed using Matlab software to increase the image quality prior to applying a PIV algorithm. In this process, the intensities of each pair of consecutive images were harmonized, and droplet edge enhancement was also carried out. In addition, in order to investigate the droplet atomization processes, a PDPA system was employed to measure the distribution of droplet diameter and velocity during the spray injection at a distance of 20 mm, 40 mm, and 60 mm from the nozzle. The wax spray had a cone angle of 33.2 degrees at an injection pressure of 10 MPa. Larger droplets of higher velocity were observed in the region of the nozzle, but as the droplets proceeded in the axial direction, smaller droplets of lower velocity were observed. Most of the droplets in the spray had a velocity between 40 and 60 m/s. By comparing the Sauter mean diameter (SMD) profiles and velocity distributions at distances of 20, 40, and 60 mm from the nozzle, droplet atomization was found to be markedly affected by distance. That is, as distance increases, the droplets tend to be smaller and of lower velocity due to loss of momentum. Comparing the droplet velocity distributions obtained by the PIV and PDPA, similar trends are observed at a distance of 20 mm, such as the maximum velocity value of 78 m/s and symmetric distribution of the peak value. Also, we confirmed that the PDPA result showed more detailed information regarding velocity distribution.