Droplet collision processes in an inter-spray impingement system

Abstract

The main objectives of the present article are in developing and evaluating a new model for the droplet collision, and in discussing the physical feature for the mutual impinging sprays. The new model is originally devised to be capable of predicting the droplet collision-induced breakup accompanied with the formation of satellite droplets. From the well-established conservation equations, the several formulae are newly proposed by consideration of some important regimes such as bounce, coalescence, and stretching and reflexive separation. This formulation makes it possible to predict the number of satellite droplets, and the droplet sizes and velocities. The extensive experiments are conducted for the inter-spray impingement systems under the various conditions to investigate the influence of impinging angle and impingement distance upon the spray characteristics. The droplet sizes and velocities are measured by the phase Doppler particle analyzer system and the distribution of liquid volume fraction is also measured by the self-manufactured patternator. In addition, numerical predictions by the new model and the O’Rourke model are compared with experimental data for the various parameters. It is found that the SMD (Sauter mean diameter) measured in the downstream region after inter-spray impingement are 40% smaller than those for the case of single nozzle. The new model shows vigorous breakup during collision, which is no longer seen in the O’Rourke model.