Aerated Circular and Elliptical Liquid Jets in a Gaseous Crossflow

Abstract

In this study, the atomization of an effervescent atomizer with an elliptical and circular orifice was investigated experimentally in the gaseous crossflow. The shadowgraph technique was used to visualize the near field of the spray atomization. To measure the spray penetration height in crossflow, image processing was performed on the shadowgraph images based on two different approaches: (i) a threshold analysis of average spray images and (ii) standard deviation images of spray. By comparing these two approaches, it is found that the penetration heights obtained from the standard deviation images were much higher since these images were able to capture small droplets more accurately. Moreover, based on the standard deviation images of spray, an empirical correlation for the spray penetration height was developed as a function of gas-liquid mass flowrate ratio, liquid-air momentum flux ratio, orifice aspect ratio, and downstream location. The laser diffraction technique was used to analyze the particle size of the aerated elliptical and aerated circular jets in a gaseous crossflow. For each orifice shape, the effect of gas-liquid ratio and downstream location on the Sauter mean diameter (SMD) was studied. The results show that the aerated circular jet penetrates higher into the gaseous crossflow than the aerated elliptical jet. Besides, the aerated circular jet in crossflow mainly generates smaller drop sizes compared to the aerated elliptical jet.