High-frame-rate planar laser-induced fluorescence imaging of diesel sprays using pulse burst diagnostics

A planar laser-induced fluorescence technique for spatially and temporally resolving individual diesel fuel injection events into various gas temperatures and pressures was demonstrated. An optically accessible chamber of constant temperature and pressure was used to create the desired thermodynamic state of gas. The chamber was capable of achieving typical thermodynamic states seen at top dead center of the compression stroke in a four stroke diesel engine. The third harmonic of an Nd:YAG laser supplied excitation near 355 nm, which was provided at high frequencies using a pulse-burst diagnostic scheme. Individual pulses of 35 mJ in energy and 10 ns in duration were provided at rates of 10 kHz and 20 kHz. The UV laser beam was passed through a calibration cell filled with a laser dye, which was used for spatially correcting variations in individual laser pulses. The technique demonstrated that individual species concentrations can be temporally resolved using pulse-burst lasers