Effectiveness of Windscreens on Modifying Airflow Around a Sprayer Boom

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.