ID 233

Velocity and drop size distribution in flow blurring atomization for high viscosity liquids

 

Abstract:

With the current consumption of limited petroleum resources, biodiesels are fast becoming one of the promising options for combustion based energy harnessing. But the physical properties like high viscosity and density make it difficult to atomize biodiesels which is very important for efficient combustion of liquid fuels. One of the unconventional techniques of twin-fluid atomization, called as flow blurring atomization, is studied in this work for its atomization capabilities in the context of high viscosity liquids. Flow blurring atomization utilizes small amount to gas mixing with the liquid fuel just upstream of the injector orifice and the two-phase mixture exits the orifice in the form of fine spray. Mixture of water and glycerol (20:80) is used in these experiments for simulate the high viscosity (32.3 mm2/s as compared to 33 mm2/s for Jatropha oil). Systematic experiments conducted over a wide range of pressure drops and gas-to-liquid ratios (GLRs) include measurement of velocity field using PIV and drop size distribution using shadow imaging technique. Increase in cone angle was noticed with increase in GLR. It was observed that the average axial velocity of droplets first increases downstream of the orifice and starts decreasing after some distance. This can be attributed to the expansion of air near the orifice and slowing down farther due to entrainment effects. Decrease in axial velocity along radial direction was observed as expected. Mean drop size was found to decrease with increase in GLR and further investigations on drop size variation are in progress.