Laser-based spray diagnostics in commercial fuels using a new all-solid-state laser system
We present a new approach for spray diagnostics in practical fuel sprays without the need of using model fuels. Commercial fuels for internal combustion engines have large absorption cross-sections in the UV and the blue. This absorption hinders measurements and yields fluorescence that is difficult to quantify and interferes with fluorescence from conventional tracers. Therefore, tracers have been chosen that allow excitation in the red where the fuels are transparent. A new all-solid-state Nd:YAlO3 laser system was developed that emits pulse bursts at 671 nm. The individual laser pulses have lengths of ~30 ns and a minimal temporal delay of 30 µs and are therefore suited for time-resolved measurements of spray formation, transport and evaporation. In this work we characterize two possible candidates for LIF tracers: Rhodamine 800 and Atto 680 in terms of relative fluorescence quantum yield and absorption cross-section in a Diesel environment as well as temperature dependence of the LIF intensity. First results of laser-sheet dropsizing experiments with Rhodamine 800 as a fluorescence tracer in a model Diesel spray are presented.
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