Abstract
High-pressure diesel fuel sprays and their internal structure are observed using a novel visualization technique based on laser-induced fluorescence (LIF). A synchronization system is developed to control the timings of fuel injection, laser emission and image acquisition so as to capture spray images at an arbitrary stage of their developing process. Greatly magnified images of fluorescence dye, Rhodamine B, are taken and the internal velocities of fuel spray are measured by PIV in the core of the spray. The results show that branch-like structures are clearly visualized and diesel spray droplets exist along them. Fuel spray droplets are rapidly decelerated from about 300 m/s to 3-6 m/s at a time 4 ms after the injection.
