Experimental analysis of global rainbow technique: sensitivity of temperature and size distribution measurements to non-spherical droplets

Sprays characterization asks to measure a large number of parameters as: particle size distribution, particle velocity, particle concentration, particle shape, particle temperature, particle composition, etc. For each of these parameters specific measurement strategies and associated devices have been developed along the years. Each of these techniques possesses its own advantages and limitations. Global rainbow technique (GRT) is a promising technique used to measure the temperature of liquid droplets with a few degrees of accuracy. The technique also provides an estimation of the droplet size distribution. It has been claimed that GRT is not sensitive to the shape of the particle. The objective of this work is to experimentally quantify the accuracy of GRT when applied to spherical and non-spherical droplets. The size distribution extracted from global rainbow signals are also compared with shadow imaging and PDA measurements.