Breakup of Turbulent and Non-Turbulent Liquid jets in Gaseous Crossflows

Abstract

An experimental and computational investigation of the primary breakup of nonturbulent and turbulent round liquid jets in gas crossflow is described. Pulsed shadowgraph and holograph observations of jet primary breakup regimes, conditions for the onset of breakup, properties of waves observed along the liquid surface, drop size and velocity properties resulting from breakup and conditions required for the breakup of the liquid column as a whole, were obtained for air crossflows at normal temperature and pressure. The test range included crossflow Weber numbers of 0-2000, liquid/gas momentum ratios of 100-8000, liquid/gas density ratios of 683-1021, Ohnesorge numbers of 0.003-0.12, jet Reynolds numbers of 300-300,000. The results suggest qualitative similarities between the primary breakup of nonturbulent round liquid jets in crossflows and the secondary breakup of drops subjected to shock wave disturbances with relatively little effect of the liquid/gas momentum ratio on breakup properties over the present test range. The breakup of turbulent liquid jets was influenced by a new dimensionless number in terms of liquid/gas momentum ratio and the jet Weber number. Effects of liquid viscosity were small for present observations where Ohnesorge numbers were less than 0.4. Phenomenological analyses were successful for helping to interpret and correlate the measurements.

Fuel Jet in Cross Flow - Experimental Study of Spray Characteristics

“…Presumably these larger structures accelerate process of jet disintegration by aerodynamic shearing. It is worth to note that distances at which fuel jet disintegrates in this study are much shorter compared to prior studies (Wu et al, 1997;Sallam et al, 2004) that reported the CBP to lie at a distance of 8 diameters downstream of the orifice for most of the investigated cases. This discrepancy can be attributed to the difference of operating conditions and measuring techniques used for the CBP locating.…”

“…Other researchers (Sallam et al, 2004) measured column breakup point at We range of 0.5-260. Their studies yielded different value of t b /t* = 2.5.…”

Spray formation by like-doublet impinging jets in low speed cross-flows

“…Both sub-and supersonic cross-flows were examined, and the breakup mechanism of the single liquid jet was experimentally investigated. Instant shadowgraph pictures showed that the liquid column breakup resembles the secondary breakup of a spherical droplet flying in a stagnant gas [3]. The somewhat quantitative nature of the jet column fracture was also addressed in view of the wave parameters.…”

“…In-depth macroscopic studies on the spray formation in a cross flow have been made and generally focused on elucidating the spray appearance, penetration heights, velocity fields, and effects of liquid property [1][2][3][4][5]. Both sub-and supersonic cross-flows were examined, and the breakup mechanism of the single liquid jet was experimentally investigated.…”

“…Application of this convection-assisted atomization is diverse in the industry. Fuel sprays in turbojet, ramjet, scramjet combustors [1][2][3][4][5][6][7] and urea injection into automobile exhaust for a diesel NO x after-treatment [8] are representative. In these applications, the cross-flow naturally occurs in the course of breathing or exhausting the gas, hence the atomization quality can be improved with no additional expense.…”