Liquid property and nozzle effects on flight time of pulsed jet spray

Time of flight of spray droplet packets is an important design parameter in intermittent spraying when there is relative motion between the atomizer and the spray target. Flight times were measured for jets of various liquids, pulse durations, and nozzles used in roadside herbicide spraying. Liquids included surfactants to enhance deposit and polymers for stream containment. Nozzle orifice diameter, pulse duration, and liquid properties all had highly significant effects on flight time. Flight time increased as initial jet velocity decreased. Time of flight decreased with increasing surface tension and decreased with addition of polymers. Flight time was highly related to surface tension of the liquid. This implies that jet breakup and subsequent drag on the droplet packets is the predominant effect on flight. A simple parametric equation was developed to predict flight time from known release conditions, fluid properties, and nozzle-to-target configuration.