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.