Characterizing the initial spray from large Weber number impinging jets

Abstract The spray from an expanding and fragmenting liquid sheet formed by orthogonal impact of a jet onto a deflector was explored in this study. Four impinging jet nozzles were characterized with jet Weber numbers ranging from 103 to 105. The sheet breakup location and spray drop size distributions were quantified under various configurations using short exposure time photography and shadowgraphy techniques. Experimental results confirmed that the breakup distance follows a −1/3 power law with Weber number. However, the drop size behavior was much more complicated, depending not only on the jet Weber number, but also on the free jet length before deflector impact (i.e. distance between orifice and deflector). The free jet length can modify the sheet breakup mode and associated drop sizes. Drop size scaling laws were developed based on injector geometry and injection conditions from the atomization physics to correlate experimental data and explain the effect of sheet breakup mode on drop size distribution.