Effectiveness of Windscreens on Modifying Airflow Around a Sprayer Boom

Abstract

The effectiveness of porous shrouding on sprayer booms for the reduction of wind velocity in the vicinity of a spray nozzle was investigated. Tests were performed in a wind tunnel for air velocities ranging from 2.6 to 6.5 m/s (5.8 to 14.6 mph). Investigation was limited to airflow patterns and air velocity measured inside and behind a model boom. The relative difference in velocity changes was observed to be different as original wind velocities increased in front of the shrouds. There was approximately 10% greater wind velocity reduction inside and behind the boom covered with fine screen at the original wind velocity of 2.6 m/s (5.8 mph) than at 6.5 m/s (14.6 mph). It was noted that the shrouding material had a significant effect on wind speed reduction. At a wind velocity of 4.4 m/s (10 mph) and for 0.025 < P < 0.01 range of significance, a double layer of fine mesh caused 22 and 33% greater drop in wind velocity inside and behind the boom, respectively, than a single layer. There was a significant difference (P = 0.025) in velocity reductions in investigated areas between a sprayer boom angle of 60 and 80 covered with the same shroud. It was also noted that impermeable shielding over the entire front shroud gave results preferable to those obtained with partial impermeable shielding.