Liquid Jets in Subsonic Air Crossflow at Elevated Pressure

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 have been collected by particle Doppler phased analyzer (PDPA), Mie-scattering with high speed photography augmented by laser sheet, and Mie-scattering with intensified charge-coupled device (ICCD) camera augmented by nanopulse lamp. Nozzle orifice diameter, d(o), was 0.508 mm and nozzle orifice length to diameter ratio, l(o)/d(o), was 5.5. Air crossflow velocities ranged from 29.57 to 137.15m/s, air pressures from 2.07 to 9.65 bar, and temperature held constant at 294.26K. Fuel flow provides 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 proposed using drop size data measured by PDPA as follows: (D-0/D-32) = 0.267We(a)(0.44)q(0.08)(rho(l)/rho(a))(0.30) (mu(l)/mu(a))(-0.16). This correlation agrees well and shows roles of aerodynamic Weber number, We(a), momentum flux ratio, q, and density ratio, rho(l)/rho(a). Change of the breakup regime map with respect to surrounding air pressure has been observed and revealed that the boundary between each breakup modes can be predicted by a transformed correlation obtained from above correlation. In addition, the spray trajectory for the maximum Mie-scattering intensity at each axial location downstream of injector is extracted from averaged Mie-scattering images. From these results, correlations with the relevant parameters including q, x/d(o), 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.