Comparison of Central Jet and Annular Sheet Atomizers at Identical Gas Momentum Flows

Abstract

This study compares three different nozzle flow configurations - central liquid jet with surrounding gas phase, liquid sheet with central gas phase, and liquid sheet with inner and outer gas phases. To guarantee constant velocities, as well as momentum flows at the nozzle orifice, a nozzle with identical orifice areas (a central tube with inner and outer slits) was utilized in the experiments. The influence of gas velocity (GLR), dynamic viscosity of the liquid, and nozzle configuration on the resulting droplet sizes (D32, ID32,m) and primary breakup was investigated at constant liquid mass flow. A high-speed camera (HSC) was used for the detection of primary breakup, whereas droplet size measurements were performed with a phase Doppler anemometer. The variation of nozzle configuration exhibited distinct influence on the resulting breakup morphology and droplet size. Especially, for atomizing high-viscosity liquids, application of sheet configurations led to smaller droplet sizes compared to liquid jet configuration.