Atomizer Design for Agricultural Air Shear Applications

Abstract

The nozzle-atomizer on most agricultural pesticide applications must perform two basic functions. First, the spray liquid must be atomized or broken up into small drops for dispersal to plant surfaces, and secondly, the amount of liquid discharged must be controlled or metered to obtain the proper plant coverage and dosage. Most atomizers used today on agricultural sprayers produce a wide range or spectrum of drop sizes approximating a Gaussian or somewhat skewed Gaussian (skewed towards small drops) range. While no one has conclusively determined that a single drop size sprayer would produce the most desirable coverage of plant surfaces, it is widely understood that a narrowed spectrum which cuts off both the small and large end of the range, would be a desirable step forward in nozzle design, thereby, reducing the amount of spray in small drift-prone drops as well as reducing the very large drops which do not provide good plant coverage. Several new designs of nozzle atomizers have been examined in our wind tunnel drop size analyzer specifically to examine their ability to reduce drift losses through production of larger drop size ranges as well as to check these for drop size range control. A few of these designs have been marketed for ground sprayer use, but we were particularly interested in how improvement in drift-control could be attained, while still maintaining adequate plant coverage with air carrier ground and aircraft spray equipment. Our studies have pointed out the drop size characteristics of certain of the available nozzles as well as developing some further lines of nozzle design that might be suitable for this purpose.