Experimental and theoretical description of the break-up of curved liquid jets in the prilling process

A pilot-scale study of the dynamics of break-up of curved jets is presented. The jets emanate from an orifice near the base of a cylindrical drum of 0.285 m diameter. Images were captured of the jet trajectory and break-up and of the drops formed using a high speed camera. The effect of liquid dynamic viscosity (0.001–0.081 Pa s), rotation rate (30–300 rpm) and orifice size (radius 0.0005 and 0.0015 m) upon the jet break-up and drop size distributions produced were examined. Some differences between the break-up modes observed in this study and previous work (using a small lab-scale 0.085 m diameter drum) were observed and attributed to the increasing influence of wind resistance and possible mechanical vibration through the rig. Jet exit velocity and liquid viscosity are key parameters in the prediction of break-up mode at both the laboratory and pilot-scale. Break-up length was found to increase with increasing viscosity, rotation rate and orifice radius. Increasing the rotation rate resulted in an increase in the size of the satellite drops. A non-linear analysis of the Navier–Stokes equations was carried out and the numerical solutions were compared with the experiments. Some qualitative agreement was found.