INVESTIGATION OF PNEUMATIC NOZZLE OPERATION FEATURES OVER A WIDE RANGE OF PRESSURE CHARACTERISTICS USING THE LASER TIME-OF-FLIGHT METHOD
A. S. Lebedev1, A. G. Savitsky1, A. S. Severin1, V. M. Dulin1, S. V. Skryabikov2, A. V. Vishev3
1nstitute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
2Sigma-Pro LLC, Novosibirsk, Russia
3Motor Design Bureau, UEC-UMPO JSC, Ufa, Russia
Keywords: spray, pneumatic nozzle, optical flow measurement methods, laser time-of-flight method, time-shift
Abstract
This study evaluates the laser time-of-flight method for measuring droplet velocities and sizes across a wide range of pressure characteristics of pneumatic nozzles. Determination of droplet sizes is based on high-velocity registration of the delay of scattering orders when the droplet crosses the laser beam. Determination of droplet sizes and velocities is based on high-speed registration of the delay of scattering orders when the droplet crosses the laser beams cross section. Two nozzles are examined as examples: one with coaxial liquid supply and the other with the liquid supplied at an angle to the air stream. A distinctive feature of these nozzles is the requirement for a high air stream pressure relative to the sprayed liquid pressure. The aim of the research is to determine the limitations of the droplet size and velocity ranges detectable by the instrument under conditions of low air pressure, where the spray quality is suboptimal due to the presence of both low-inertia small droplets and high-inertia large droplets, as well as significant jetting. It is found that the AOM-Systems instrument is capable of simultaneously detecting spherical droplets in the size range of 5 to 200 µm with velocities ranging from 2 to 120 m/s. The greatest dispersion in droplet sizes and velocities is observed when the liquid is supplied at an angle to the air stream. The jet structure of the plume generated by the nozzles is detected by means of contre-jour visualization.
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