MEASUREMENT OF SINGLE DROPLET CHARACTERISTICS USING HIGH SPEED IMAGING TECHNIQUES

摘要

The spray droplets generated by agricultural nozzles playrnan important role in the application accuracy andrnefficiency of plant protection products. But, the process ofrngenerating and controlling small droplets of highrnuniformity, constant size and form is complex andrndifficult to quantify or model. The limitations of the nonimagingrntechniques and the recent improvements inrndigital image acquisition and processing increased therninterest in using high speed imaging techniques inrnpesticide spray characterisation.rnThe goal of this study was to apply an imaging techniquernto evaluate the characteristics of a single spray dropletrnusing a piezoelectric single droplet generator in a dropleton-rndemand mode with 4 glass nozzles and a high speedrnimaging technique.rnTests were done with a high-speed camera, microscopernlenses, and a xenon light source. Image analysisrnalgorithms were developed for droplet sizing and trackingrnon images gained from this acquisition system.rnThe experiments have shown that using the selectedrnimage acquisition and processing system, different dropletrnsizes and velocities can be measured. By changing thernpulse width and the nozzle orifice size, repeatable dropletsrncould be generated with a size ranging from 135 μm up torn461 μm. The ratio between droplet diameter and nozzlesrnorifice opening varied from 1.33 up to 3.42 depending onrnthe settings.