Liquid Jets in Subsonic Air Crossflow at Elevated Pressure

Abstract

The breakup, penetration, droplet size and size distribution of a Jet A-1 fuel in air crossflow has been investigated with focus given to the impact of surrounding air pressure. Data has been collected by Particle Doppler Phased Analyzer (PDPA), Mie-Scattering with high speed photography augmented by laser sheet, and Mie-Scattering with ICCD Camera augmented by nano-pulse lamp. Nozzle orifice diameter, do, was 0.508 mm and nozzle orifice length to diameter ratio, lo/do, was 5.5. Air crossflow velocities ranged from 29.57 to 137.15 m/s, air pressures from 2.07 to 9.65 bar and temperature held constant at 294.26 K. Fuel flow was governed to provide a range of fuel/air momentum flux ratio q from 5 to 25 and Weber number from 250 to 1000. From the results, adjusted correlation of the mean drop size has been suggested using drop size data measured by PDPA as follows; (1)D0D32=0.267Wea0.44q0.08ρlρa0.30μlμa-0.16This correlation agrees well and shows roles of aerodynamic Weber number, Wea, momentum flux ratio, q, and density ratio, ρl/ρa. Change of the breakup regime map with respect with surrounding air pressure has been observed and revealed that the boundary between each breakup modes can be predicted by a transformed correlation induced from above correlation. In addition, the spray trajectory for the maximum Mie-scattering intensity at each axial location downstream of injector was extracted from averaged Mie-scattering images. From these results correlations with the relevant parameters including q, x/do, density ratio, viscosity ratio, and Weber number are made over a range of conditions. According to spray trajectory at the maximum Mie-scattering intensity, the effect of surrounding air pressure becomes more important in the farfield. On the other hand, effect of aerodynamic Weber number is more important in the nearfield.

How do liquid fuel physical properties affect liquid jet development in atomisers?

“…Experimentally, it has been observed that more viscous liquid jets are deflected laterally by the cross flow, more than the less viscous jets. 14,15,40 An interpretation of this observation can be based on the more developed liquid velocity radial profile in the more viscous liquid jet.…”