Simulating drift by CFD: sensitivity analysis of machine and environmental parameters.
Explore the source record for details and available documents.
Agriculture↗
Biomedical subjects
D Nuyttens
Publications and source records attributed to D Nuyttens.
Spray drift as affected by meteorological conditions.
Spray drift can be defined as the quantity of plant protection product that is carried out of the sprayed (treated) area by the action of air currents during the application process. This continues to be a major problem in applying agricultural pesticides. The purpose of this research is to measure and compare the amount of drift for different climatological conditions under field conditions. Spray drift was determined by sampling in a defined downwind area at different positions in a flat meadow using horizontal drift collectors (sedimenting spray drift) and pipe cleaners (airborne spray drift) for a reference spraying. Meteorological conditions were monitored during each experiment. A drift prediction equation for the reference spraying was set up to predict the expected magnitude of sedimenting drift at various drift distances and atmospheric conditions (wind speed and temperature). This equation can be used to compare measurements using other spraying techniques under different weather conditions to the reference spraying. In 2005, more measurements will be performed to validate the statements and the model reflected in this paper.
Agriculture↗
Understanding drift from field spraying: CFD model development.
Explore the source record for details and available documents.
Agriculture↗
Optimisation of sequence and orientation for used nozzles based on few, full boom distribution measurements.
Most studies on uniformity of pesticide applications beneath agricultural spraying booms are based on the characteristics of nozzle spray patterns. When optimising general features (boom height, pressure, ...), average nozzle characteristics are used. In this research, individual nozzle characteristics are essential. When utilising slightly used nozzles, small irregularities in the nozzle spray distribution may be averaged out or amplified in the resulting full-boom distribution. A method is proposed to find whether the coefficient of variation (cv) of a field sprayer spray distribution could be optimised by altering the sequence and orientation of a given set of flat fan nozzles. A manageable model is used in order to quickly compute possible full-boom distributions (and cv's) with a given set of single nozzle spray distributions. The individual nozzle spray distributions are extracted from a limited series of full-boom spray distribution measurements (three in most cases) with randomised nozzle sequence and orientation by means of a Matlab optimisation algorithm.
Aerosols↗
A pdpa laser-based measuring set-up for the characterisation of spray nozzles.
The characteristics of agricultural sprays belong to the most critical factors affecting spray drift, deposition on plants, spray coverage and biological efficacy. Hence, within the framework of a research project about agricultural spray drift, a measuring set-up for the characterisation of spray nozzles using a Phase Doppler Particle Analyser (PDPA) was developed. This set-up is able to measure droplet sizes and velocities based on light-scattering principles. It is composed of different parts i.e.: a climate room, a spray unit, a three-dimensional automated positioning system and an Aerometrics PDPA 1D system. This paper presents a detailed description of this measuring set-up along with some first measuring results. These measurements will be used as an input for a Computational Fluid Dynamics drift-prediction model and to classify nozzles based on their driftability.
Agriculture↗
The assessment of spray drift damage for ten major crops in Belgium.
According to the Council Directive 91/414/EC pesticide damage should be assessed by considering the risk for persons arising from occupational, non-dietary exposure and risk to the environment. In this research an assessment for the pesticide damage by droplet spray drift was set up. The percentages of spray drift were estimated with the Ganzelmeier drift curves and the IMAG drift calculator. Knowing the percentages of drift and the applied doses of pesticide formulations in a given crop, the human and environmental exposures (water and bottom) were predicted. Thereupon risk indices were calculated for water organisms, soil organisms and bystanders. A risk index is the ratio of a predicted exposure to a toxicological reference value and gives an indication of the incidence and the severity of the adverse effects likely to occur. Considering the risk index it is possible to define the minimal width of an unsprayed field margin or "buffer zone" to reduce this risk at an acceptable level.
Animals↗
Comparison of operator exposure for five different greenhouse spraying applications.
The European Crop Protection Association (ECPA) and the Agricultural Research Center (CLO-DVL) joined forces in a project to stimulate the safe use of pesticides in southern European countries. CLO-DVL optimized a method using mineral chelates as tracers on collectors. This quantitative method to evaluate spray deposits was used to compare operator exposure from several greenhouse spraying techniques. Operator exposure measurements were of a comparative nature. Five application methods were investigated: a standard spray gun with an operator walking forwards, a spray lance with an operator walking forwards and backwards, a trolley, and a vehicle, both with vertical spray booms. The exposure was measured with patches at 15 places on operators' coveralls and gloves, using mineral chelates as tracer elements. The difference in exposure of the patches between the different techniques was very high. Walking backwards reduced exposure by a factor of 7. The exposures with the trolley and the vehicle, two innovative spraying techniques, were respectively 25 and 100 times lower compared to exposure with the standard spray gun. Operator exposure while walking forward with the spray lance was about two times higher than with the spray gun. Besides very large differences in exposure among the five techniques, there were also large differences in exposure among various parts of the body. All of this is important in consideration of operator safety and for the parts of the body that need to be protected most.
Aerosols↗
Wind tunnel evaluation of several tracer and collection techniques for the measurement of spray drift.
In the history of pesticide drift measuring techniques, different tracers and a lot of different collection techniques have been used. At the start of a new Flemish project 'Protecting the Flemish environment against drift - The importance of drift-reducing techniques', wind tunnel tests have been executed to select the most efficient tracer and collection technique. As tracer types a fluorescent tracer Renaissance W15, 2 different chelates, a NaCl-solution and a fungicide Tolylfluanide were used. 2 different collection techniques were tested: drains incorporated in the wind tunnel floor filled with filter paper and filled with cloths. The recovery of the different tracers combined with the 2 collection materials was calculated. The advantages and disadvantages of the tracers and collection materials are enumerated in this article.
Air Pollutants↗
Optimisation of a vertical spray boom for greenhouse spraying applications.
The European Crop Protection Association (ECPA) and CLO-DVL joined forces in a project to stimulate a safe use of pesticides in Southern European countries. CLO-DVL optimised a method with mineral chelates to evaluate deposition tests. This quantitative method to evaluate spray deposits and to check spray distributions is used to assess two novel spraying techniques. Deposition tests with water-sensitive paper and mainly with the manganese and molybdenum chelates as tracer elements were performed with a manually pulled trolley and a motorised vehicle both equipped with vertical spray booms. Filter papers were attached to the tomato and pepper plants at several heights to obtain an indication of the spray distribution in the crop. Particular attention was paid to the effect on the spray distribution of the vertical nozzle distance (35 cm vs. 50 cm) and the spray distance to the crop. The tests proved that a nozzle spacing of 35 cm delivers a much better spray distribution than one of 50 cm. The optimal spray distance for flat fan nozzles with a spray angle of 80 degrees and a nozzle spacing of 35 cm is about 30 cm.
Aerosols↗