Responsible and efficient use of agrochemicals is a balance between mitigating the undesirable drift and other off-site movement and optimizing the efficacy of the applied spray. Often, these demands can be in direct conflict, e.g., very large droplets reduce drift but may run off the target or may be ineffective against pests on leaf undersides. Depending on the immediate weather conditions, the proximity to sensitive crops or areas, the pesticides being applied and the target pests, the applicator may desire to "fine tune" the application parameters such as nozzles, use of adjuvant, rate of active ingredients and method of application. Along these lines, applicators need additional methods and equipment to balance or optimize spray tank adjuvant performance and economics to achieve drift mitigation goals for a given application. A particular problem develops when a mix of chemicals is applied simultaneously. In these cases, a "tank mix" of many chemicals and adjuvants is prepared and sprayed. The interactions in the physical properties between the various products is virtually impossible to predict and there are virtually an infinite number of combinations. OBJECTIVES: The goal of this project is to develop a simple device for determining the properties of fluids that are important for the application of pesticides in liquid sprays. The basic technique to be investigated is the relationship between vibration of fluid during a perturbation in flow and the viscosity, density and surface tension of the fluid. The technical objectives are: 1) Expand and apply the underlying theory on the relationship between observed vibration and fluid physical properties; 2) Conduct parametric experiments to individually correlate the fluid physical properties of viscosity, surface tension and density to the spectral characteristics of vibration of flat sheets of fluid from spray nozzles; 3) Design and test a handheld, fieldworthy device to determine the vibration characteristics of pesticide tank mixes and indicate the results to a spray equipment operator; 4) Conduct droplet size tests on tank mixes and nozzles used by applicators and to compare the results with in-field vibration measurements, and, 5) Determine the feasibility of real-time, in-line fluid property and atomization measurement systems for agricultural and industrial applications. APPROACH: The fundamental theory of sheet breakup from fan-type spray nozzles has been analyzed and developed over the fast 50 years and provides some guidance to the understanding between fluid properties, such as viscosity, surface tension (dynamic and equilibrium) and density and the resulting velocity fields, instabilities and wavelengths of the fluid web exiting nozzles. The theory will be applied to conventional agricultural spray nozzles and fluids to predict wavelengths and frequencies of break-up. Parametric, fundamental experiments, using known fluids with known properties will be conducted and the results compared to the underlying theory. Known fluids will consist of aqueous mixtures of common fluids such as alcohols and oils. Basic fluid property measurements will also be conducted on the test fluids and the results correlated with the results from parametric experiments. The data on fluid wavelength and frequency response will be used to investigate correlations with the fluid properties. Using the resulting correlations and basic frequency data, a test device will be designed and fabricated for use in the field with actual tank mixes of complex agricultural fluid mixtures of pesticides, fertilizers and adjuvants. The results from the device will be correlated with droplet size measurements of the resulting spray produced using common agricultural spray nozzles using the fluids
