Experimental apparatus Fig xA Experimental setup of the spray

4. Conclusions
Spray formation characteristics; High speed liquid jet; Dimensionless analysis; Atomization mechanism
1. Introduction
The breakup and atomization of high speed liquid jets are highly dynamic processes which are widely encountered in today’s direct-injection gasoline and diesel engines. The spray characteristics such as spray tip penetration, cone angle, and drop size distribution are crucial for engine combustion and emission formation [1] and [2]. Therefore, understanding the transient spray behavior and its temporal characteristics are essential for developing advanced engine combustion concepts in meeting the ever-stringent fuel efficiency and emission regulations on internal combustion engines.
The objective of the current study A939572 to investigate the transient development of spray formation from a force competition perspective. The time-variant macroscopic spray characteristics were firstly obtained using planar Mie scattering technique. Those spray data were subsequently analyzed to identify different temporal stages of spray formation. Then, the effects of the various forces (inertia, viscous, surface tension, and aerodynamic) on the temporal development of spray characteristics are investigated. The effects of force competition on spray formation are quantified using dimensionless Reynolds number, Weber number and gas-to-liquid density ratio. New correlations between spray characteristics and those dimensionless numbers are established to reveal the physical mechanism of spray formation. Based on those corrections, the complex mechanisms of high pressure spray formation can be explicitly elucidated.