THE EFFECT OF INITIAL AMBIENT TURBULENCE LEVELS ON ISO-OCTANE INJECTION SPRAYS

Iso-octane, injected at high pressure into ambient nitrogen with different prescribed nearly isotropic turbulence levels, characterized by the root-mean-square (RMS) turbulence velocity, is explored experimentally. Mie scatter laser sheet and Schlieren techniques are combined with a high-speed camera to capture images of the vapor and liquid phases simultaneously as a function of injection pressure and ambient turbulence level. These indicate that the latter has a significant influence on tip penetration length, penetration width, cross-sectional area, and velocity. Increased initial ambient turbulence levels lead to reductions in the penetration length in the axial direction and increases in the penetration width in the radial direction; it is also shown to improve fuel evaporation and mixing.