MODELING FINER DROPLET AERIAL SPRAY DRIFT AND DEPOSITION

Abstract

Aerial application models represent the effects present in the near wake of the aircraft by simple modelsapproximating the detailed physics found there. The important inputs into these models include the aircraftcharacteristics, flight parameters, meteorological conditions, tank mix characteristics, and droplet size distribution. Manynumerical studies have shown that release height, wind speed, and nozzle atomization are the main contributing factors tospray drift. With control of release height and wind speed essentially an application issue at the time of spraying, controlof the droplet size distribution can be done well ahead of time and with deliberate intent. In this regard spray qualityclassification appears to be overtaking the industry today, especially in light of the development of ASAE S-572. In thisarticle we explore the deposition and drift of the smallest droplets (fine fraction) at the limit of the classification scheme,in particular reaching toward very fine droplet sizes, typical of ultra low volume (ULV) spraying.