Parametric study on the internal geometry affecting agricultural air induction nozzle performance

Abstract

With recent advances in agricultural engineering, precision spraying has become of prime interest to avoid chemical drift or rebound and to minimize water and soil pollution. Air induction nozzles are reliable alternatives for conventional nozzles to overcome these challenges. A parametric study was designed both experimentally and numerically to investigate the effect of each design parameter on the performance of an air induction nozzle. A number of components were designed, manufactured, and tested. The spray structure was captured using a planer Mie scattering imaging system. The mean droplet size was measured using a Malvern particle sizer based on a laser diffraction technique. The results indicated the influence of each geometrical component on the resultant behavior. The internal geometry of the nozzle was found to significantly impact the stability and structure of the spray such as the fluid behavior inside the nozzles and the air-to-liquid mass flow ratio, as well as spray angle, droplet size, and uniformity. The key findings of this study indicate that pre-orifice inlet diameter primarily controls the flow behavior, air, and liquid inlet diameters of the ejector section impact mainly on the air-to-liquid mass flow ratio, the geometry of the mixing chamber mainly controls the stability of the resulting spray, and the geometry of the flat-fan tip essentially controls the spray angle and droplet size. The results can help nozzle designers optimize the design target, enhance atomization efficiency, and understand the effect of the various design parameters on the internal flow behavior of air induction nozzles.