The control of NOx, stability and re-light in combustors is strongly influenced by the patternation of the fuel and its subsequent mixing with air. This paper reviews imaging approaches to two-phase flow and fuel vapour. The two main methods discussed are laser-induced fluorescence (LIF) for the imaging of volume fraction of fuel vapour or the volume fraction of liquid fuel and laser sheet drop-sizing (LSD) for the imaging of fuel droplet size. A range of practical applications is presented to illustrate the techniques, these include a 1 atm lean prevaporized premixed (LPP) combustor, a study of the pilot zone of a double annular system and the study of spray patternation and droplet size for a variety of fuel injectors.
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