高速空气流中两个空气雾化喷嘴的喷雾相互作用

Air atomizing nozzles are used to produce a polydisperse distribution of droplets. When droplets exiting a nozzle collide with droplets from other sprays, they may either coagulate and grow in size or potentially undergo further atomization and reduce in size. The size and relative motion of the individual droplets will have a significant effect on the process. In addition, when the droplets are subjected to external velocities that result in turbulent flow, shear coagulation can have a substantial impact on the combined spray distribution, especially for larger droplets. For our current study, we are developing an array of air atomizing nozzles to produce airborne icing clouds, with median volume diameters (MVD) in the 20 to 50 m range. The nozzles are spaced approximately 10 centimeters apart hor-izontally and subject to wind speeds ranging from 50 to 140 knots. The shearing effect created by the relative wind speed may reduce the initial droplet size by secondary atomization, while the droplet interactions may lead to coagu-lation. These competing phenomena were evaluated using an Artium Phase Doppler Interferometer (PDI) to charac-terize the size distribution of droplets undergoing simultaneous shear and coagulation. The data show that the air flowing past the nozzles had a significant effect upon the droplet size for individual nozzle sprays, reducing the MVD by 27% on average. The data also showed the combined spray from two nozzles had a 9% larger MVD than that from a single nozzle; however, with the reduction in droplet size due to the high velocity (HV) air flow, the overall MVD was still reduced (24% on average). This paper further describes the test results for one and two noz-zles generating droplets in still air and with HV air flow, and how the droplet size and water flow rate appeared to influence the evaporation /coagulation ratio.