Penetration of spray in apple trees as a function of airspeed, airflow, and power for tower sprayers.

摘要

In orchards, tower sprayers are machines where the droplet-laden air is released horizontally as a two-dimensional air jet extending the full height of the trees. Such sprayers offer good potential for drift reduction because very little, if any, spray material is projected above the top of the orchard canopy. To be successful, such sprayers must provide adequate spray penetration within the canopy. In this study, the effect of air speed and air flow rate on the penetration of spray in the canopy was measured. Spray was collected by impacting of droplets on rigid cylindrical targets. From the data, models of spray coverage at different horizontal distances from the source of air were obtained. These models were then used to relate power requirements to coverage. The effect of the sampling process on the coverage data is discussed. It was shown that, at constant power, priority should be given to air flow rate over air speed and that adequate coverage can be obtained at low power. Furthermore, doubling the fan power from 4 to 8 kW increased target coverage by no more than 7%, a small difference..