Dynamics of Turbulent Air-Flow in Droplet Driven Sprays

Abstract

This paper presents a study of the fundamental mechanics of droplet and gas motion in sprays. Only vertical sprays are considered and our theoretical analysis identifies two main flow zones, corresponding to where the droplet velocity is much greater than or of the same order as the induced air velocity . Analytical asymptotic results for the induced air velocity for small and large downstream distances confirmed a full numerical calculation and also agreed with experimental results. The second half of the paper deals with some of the most important aspects of spray jets in a cross flow. We find that the ratio of the cross-wind speed to the induced air jet speed U ₀/V _j is a crucial factor for specifying the dynamical behaviour. We present results for an axi-symmetric spray in uniform cross flow for both weak and strong cross-winds.