EXPERIMENTAL INVESTIGATION OF THE CORRELATION BETWEEN NOZZLE FLOW AND SPRAY USING LASER DOPPLER VELOCIMETER, PHASE DOPPLER SYSTEM, HIGH-SPEED PHOTOGRAPHY, AND X-RAY RADIOGRAPHY

摘要

This paper presents experimental investigations of the nozzle flow and spray in a pressure atomizer. Different inlays in the nozzle were used to modify the nozzle flow. To isolate the influence of turbulence and cross-flow velocity on the primary atomization, an operating point without cavitation in the nozzle was selected. This was monitored using a high-speed camera in combination with a long-distance microscope. Inside the transparent nozzle, a two-velocity component laser Doppler velocimeter (LDV) was used to measure velocity and turbulence profiles at the nozzle exit. For the characterization of the spray, different measurement techniques have been applied: high-speed photography to determine the spray angle, a phase Doppler system (PDA) for the velocity distribution and droplet sizes in the spray, and X-ray radiography for the spray angle and to evaluate the liquid density distribution. Finally, the correlations between the flow characteristics in the nozzle and the spray characteristics are discussed using the experimental results.