Research On Theory And Trial Of Double-foil Shield In Reducing Spray Drift

Double-foil shield spraying gives a good performance in reducing spray drift characterized with simple structure and no-driven. The curtain flow guided by the two arc blocks is the key point on reducing spray drift. Theory of double-foil shield on reducing drift was investigated by simulation method. Then the shield structure was improved to reduce drift further. At last, wind tunnel experiment was conducted to evaluate the effect of the improved shield on reducing spray drift.The theory of double-foil shield on reducing drift was analyzed by simulating with computational fluid dynamics software package. The air direction and velocity was changed through modifying the shield structure, and the effect of the air direction and velocity on the droplets drift was compared. The results showed that spray deposition increased with the curtain flow velocity increasing in -X direction and -Y direction, and the extended curtain can also reduce spray drift.An improved test shield was devised to evaluate the effect on increasing the spray deposition. Comparison between simulation experiments and wind tunnel tests show that the results from simulation agreed with that from wind tunnel. The improved shield spraying is better than the unimproved shield spraying, and the conventional spraying without any shield is the worst in spray deposition.In wind tunnel tests, under weather condition, ambient temperature was 10.3℃~ 19.95℃, RH was 30.4%~55.6%. Nozzle employed Lechlor ST110—015, and sprayed at 0.4MPa. When wind velocity was 3m/s , the spray deposition of improved shield spraying and unimproved shield spraying were 73.35% and 66.90% respectively. The deposition were 75.81% and 63.57% respectively at wind velocity of 5m/s.