Measurement and prediction of atomization parameters from fixed-wing aircraft spray nozzles

A survey of spray nozzles used by the agricultural aviation industry identified nozzles and operating conditions that were most commonly used in applying agricultural chemicals in the U.S. Eleven hydraulic nozzles and their typical range of operating conditions were selected from the survey. These eleven nozzles were subjects of a research program to develop spray atomization models that would be easy for aerial applicators to use in adjusting operations to control spray drift from aerial agricultural sprays. Each nozzle was conducted through a series of trials in a spray nozzle test facility equipped with a laser spectrometer to develop a data set for atomization model development. Computer spreadsheet models were developed from the data set with operator selection of a specific spray nozzle and inputs of nozzle orifice size, spray discharge angle, spray pressure, and aircraft airspeed. The model outputs included droplet size parameters, drift potential parameters, and droplet spectra classification. Aircraft speed was the dominating factor influencing atomization from most of the spray nozzle models. Validation studies showed that the models gave useful estimates of the computed parameters for estimating compliance with product label and state regulatory agency requirements for spray drift mediation. The models are available on-line and in a user handbook as well as in the current technical presentation.