Visualization of Developing Process of Diesel Spray

Abstract

High-pressure diesel fuel sprays and their developing process after injection were observed using a novel visualization technique based on the laser-induced fluorescence (LIF). The fuel chosen was O-Solvent in which Rodamine B(C28H31CIN2) was dissolved as fluorescent dye at a mass concentration of 30ppm. A frequency-double Nd:YAG laser (532 nm wavelength and 7ns pulse width) was used to excite Rodamine B, which emits fluorescence of 590nm wavelength. A unique synchronization system was developed to control the timing of fuel injection, laser emission and image acquisition so as to capture spray images at an arbitrary stage of their developing process. It was demonstrated that not only the overall structures but also the deeply internal structures of the spray were clearly visualized with spatial resolution fine enough to image individual fuel droplet in the core of the spray.