Droplet sizing in fuel injections by stimulated Raman scattering

Measurements of droplet diameter in hydrocarbon fuel injection sprays were carried out using stimulated Raman scattering (SRS). In this method, the number of droplets contributing to an SRS signal was determined by the depth of field of the lenses associated with the pump focusing and signal collimation. Frequency analysis was applied to measure multidroplet nonlinear Raman spectra by the occurrence of morphology-dependent resonances (MDRs), making it possible to size several droplets simultaneously (provided that there are resolvable MDRs in the SRS spectrum).