Simultaneous planar measurement of size and three-component velocity of droplets in an aero-engine airblast fuel spray by stereoscopic interferometric laser imaging technique

A new technique is proposed to simultaneously measure the size and three-component velocity of droplets, which is the extension of the interferometric laser imaging technique to the stereoscopic configuration. The optical compression concept is also utilized to avoid droplet image overlap for the application to the relatively dense region of sprays. The applicability of the technique is successfully demonstrated by using a practical aero-engine airblast fuel spray field. The results are compared with those by the phase Doppler anemometry to evaluate the performance. The results by the two techniques show good agreement. The influence of the air pressure drop through the nozzle is also studied by the present technique and the results are reasonable and consistent with those from literatures. Some important characteristics of the complicated counter-swirling airblast spray field is clearly revealed, taking advantage of the present technique, such as the droplet motions influenced by the air flow in the recirculation zone and in the attenuated circumferential counter-swirl shear-layer structure, not only by the mean velocity values, but also by the various correlations among droplet properties.