Image Analysis of Diesel Sprays 921628

Time resolved measurements of non-evaporating, non-burning fuel sprays injected into a quiescent atmosphere were performed. The experimental parameters included ambient gas density, mass of fuel injected per stroke, pump speed, and nozzle diameter. High speed films of fuel sprays were obtained using a rapidly pulsed Cu-vapor laser in synchronization with a high frame rate film camera. The laser light intensity transmitted through the spray was recorded directly by the film camera. The information encoded on the film was subsequently digitized using a projector/CCD camera system. Finally, instantaneous ensemble averaged properties of droplets constituting the spray were estimated by quantitative analysis of the digitized transmission images. These measured properties included the Sauter mean diameter (SMD) averaged over the entire spray or over a given cross-section. In addition, the images yielded other spray parameters such as tip penetration, cone angle, and injection duration.
The results showed that SMD decreased as injection proceeded. Furthermore, the SMD approached an asymptotic size. Longitudinal variation of SMD at a specific time indicated that the size reached a minimum in the spray interior. These results were compared with other data obtained with a phase-Doppler particle analyzer (PDPA) [1] utilized on the same experimental configuration. Comparison with a breakup model developed at UW-Madison [2] as well as other models was made. The data of this study are in reasonable agreement with both the PDPA data and these spray models.


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